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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of
the Securities Exchange Act of 1934 (Amendment No.          )

Filed by the Registrant ý

Filed by a Party other than the Registrant o

Check the appropriate box:

ý

 

Preliminary Proxy Statement

o

 

Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

o

 

Definitive Proxy Statement

o

 

Definitive Additional Materials

o

 

Soliciting Material under §240.14a-12

 

SYNTA PHARMACEUTICALS CORP.

(Name of Registrant as Specified In Its Charter)

 

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

o

 

No fee required.

ý

 

Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11.
    (1)   Title of each class of securities to which transaction applies:
        Common Stock, par value $0.0001 per share ("Common Stock"), of Synta Pharmaceuticals Corp. ("Synta")
 
    (2)   Aggregate number of securities to which transaction applies:
        253,878,117 shares of the Common Stock of Synta to be issued pursuant to that Agreement and Plan of Merger and Reorganization, or Merger Agreement, dated as of April 13, 2016, by and among Synta Pharmaceuticals Corp., Saffron Merger Sub, Inc. and Madrigal Pharmaceuticals, Inc., based on the assumptions discussed in this proxy statement.
 
    (3)   Per unit price or other underlying value of transaction computed pursuant to Exchange Act Rule 0-11 (set forth the amount on which the filing fee is calculated and state how it was determined):
        Calculated solely for the purpose of determining the filing fee. The maximum aggregate value was determined based upon the product of (i) 253,878,117 shares of Synta's Common Stock (determined before applying any adjustments for the reverse split contemplated by the Merger Agreement) and (ii) $0.374 per share (value of one share of Common Stock of Synta, based on the average of high and low prices of Synta's Common Stock as reported on The NASDAQ Global Market on May 18, 2016). In accordance with Section 14(g) of the Securities Exchange Act of 1934, as amended, the filing fee was determined by multiplying the amount calculated in the preceding sentence by 0.0001007.
 
    (4)   Proposed maximum aggregate value of transaction:
        $94,950,416
 
    (5)   Total fee paid:
        $9,561.51
 

o

 

Fee paid previously with preliminary materials.

o

 

Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing for which the offsetting fee was paid previously. Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing.

 

 

(1)

 

Amount Previously Paid:
        
 
    (2)   Form, Schedule or Registration Statement No.:
        
 
    (3)   Filing Party:
        
 
    (4)   Date Filed:
        
 

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LOGO

May [·], 2016

        To the Stockholders of Synta Pharmaceuticals Corp.:

        You are cordially invited to attend the annual meeting of the stockholders of Synta Pharmaceuticals Corp., a Delaware corporation, which we refer to as "we", "Synta", or the "Company", which will be held at [·], local time, on [·], 2016, at the offices of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., One Financial Center, Boston, MA 02111, or the Annual Meeting, unless postponed or adjourned to a later date. This is an important meeting that affects your investment in Synta.

        On April 13, 2016, Synta and Madrigal Pharmaceuticals, Inc., or Madrigal, entered into an Agreement and Plan of Merger and Reorganization, or the Merger Agreement, pursuant to which a wholly-owned subsidiary of Synta will merge with and into Madrigal, with Madrigal surviving as a wholly-owned subsidiary of Synta, which we refer to as the "merger." The merger has been approved by the boards of directors of both companies and the stockholders of Madrigal and is expected to close in the third quarter of 2016, subject to approval of the stockholders of Synta, Synta having a minimum net cash amount of at least $28.5 million, as well as other customary closing conditions.

        At the effective time of the merger, each share of Madrigal common stock outstanding immediately prior to the effective time of the merger will be converted into the right to receive 5.5740 shares of Synta common stock, subject to adjustment to account for a proposed reverse stock split to be implemented prior to the closing of the merger, which is described in the accompanying proxy statement. Synta stockholders will continue to own and hold their existing shares of Synta common stock. Immediately following the effective time of the merger, the post-closing ownership of the shares outstanding will be approximately 36% held by Synta's current equityholders and 64% held by Madrigal's current securityholders, excluding equity compensation to be awarded immediately following the closing of the merger.

        Effective as of the closing of the merger, (i) the officers of the combined company will include Paul A. Friedman, M.D., Chief Executive Officer and Chairman of the board of directors; Rebecca Taub, M.D., Chief Medical Officer, Executive Vice President, Research & Development and Director; and Marc R. Schneebaum, Chief Financial Officer and (ii) the combined company's board directors will be Paul A. Friedman, M.D., who will be the Chairman of the board of directors of the combined company; Fred Craves, Ph.D., who will be the lead director and who currently is the founder and a managing director of Bay City Capital; Rebecca Taub, M.D.; Keith R. Gollust, the current Chairman of the board of directors of Synta; a director mutually designated by Synta and Madrigal who meets the Securities and Exchange Commission, or SEC, and NASDAQ independence requirements; and two additional Madrigal designees meeting the SEC and NASDAQ independence requirements. The resignations from Synta's board of directors of each of Bruce Kovner, Donald W. Kufe, M.D., Scott Morenstein, William S. Reardon, C.P.A., Chen Schor, and Robert N. Wilson will be effective as of the effective time of the merger. Following the merger, the headquarters of Synta will be located at 500 Office Center Drive, Suite 400, Fort Washington, PA 19034, Madrigal's current headquarters.

        Shares of Synta common stock are currently listed on The NASDAQ Global Market under the symbol "SNTA." Prior to completion of the merger, the parties intend to file an initial listing application with NASDAQ relating to the combined company, pursuant to NASDAQ's "change of control" rules. After completion of the merger, Synta will be renamed "Madrigal Pharmaceuticals, Inc." and expects to trade on The NASDAQ Global Market or The NASDAQ Capital Market under the symbol "MDGL." On May 18, 2016, the last trading day before the date of this proxy statement, the closing sale price of Synta common stock was $0.3605 per share.


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        As part of the Annual Meeting, Synta will be seeking the stockholder approvals necessary to complete the merger and related matters. At the Annual Meeting, Synta will ask its stockholders to, among other things:

        Certain Synta stockholders who, in the aggregate, own approximately 18.2% of the outstanding shares of Synta common stock, are parties to voting agreements with Synta and Madrigal whereby such stockholders agreed to vote in favor of the issuance of Synta common stock in the merger as contemplated by the Merger Agreement. The stockholders of Madrigal have approved the merger. In addition, all securityholders of Madrigal are parties to lock-up agreements, whereby such securityholders agreed not to, except in limited circumstances, sell or transfer, or engage in swap or similar transactions with respect to Madrigal securities, including, as applicable, shares of Synta common stock to be received in the merger, from April 13, 2016, the date the lock-up agreements were executed, until 180 days after the closing date of the merger.

        After careful consideration, by unanimous approval of all directors participating in the vote, Synta's board of directors has determined that the merger is fair to, and in the best interests of, Synta and its stockholders, has approved the Merger Agreement, the merger, the issuance of shares of Synta common stock to Madrigal's stockholders pursuant to the terms of the Merger Agreement, the change of control of Synta, and the other actions contemplated by the Merger Agreement, and has determined to recommend that the Synta stockholders vote to approve the same. Accordingly, the members of Synta's board of directors unanimously recommend that Synta's stockholders vote "FOR" each of Proposal Nos. 1 through 8 described above.

        Your vote is very important, regardless of the number of shares you own. Whether or not you expect to attend the Annual Meeting in person, please complete, date, sign and promptly return the


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accompanying proxy card in the enclosed postage paid envelope to ensure that your shares will be represented and voted at the Annual Meeting.

        More information about Synta, Madrigal and the proposed transaction is contained in this proxy statement. Synta urges you to read the accompanying proxy statement carefully and in its entirety. IN PARTICULAR, YOU SHOULD CAREFULLY CONSIDER THE MATTERS DISCUSSED UNDER "RISK FACTORS" BEGINNING ON PAGE 26.

        Synta is excited about the opportunities the merger brings to its stockholders. Thank you for your consideration and continued support.

        Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this proxy statement. Any representation to the contrary is a criminal offense.

        The accompanying proxy statement is dated [·], 2016, and is first being mailed to Synta stockholders on or about [·], 2016


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LOGO
      Synta Pharmaceuticals Corp.
125 Hartwell Avenue
Lexington, MA 02421
Tel: (781) 274-8200
Fax: (781) 274-8228
www.syntapharma.com

NOTICE OF 2016 ANNUAL MEETING OF SYNTA STOCKHOLDERS
TO BE HELD ON
[·], 2016

Time:   [·]

Date:

 

[·], 2016

Place:

 

The offices of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.
One Financial Center, Boston, MA 02111

Purposes:

 

1.

 

To approve the Agreement and Plan of Merger and Reorganization, or the Merger Agreement, dated as of April 13, 2016, by and among Synta Pharmaceuticals Corp,, or Synta, Saffron Merger Sub Inc., and Madrigal Pharmaceuticals, Inc., or Madrigal, a copy of which is attached as Annex A to the accompanying proxy statement, and the issuance of shares of Synta common stock to Madrigal stockholders by virtue of the merger contemplated by the Merger Agreement;

 

 

2.

 

To approve a certificate of amendment to Synta's restated certificate of incorporation to effect a reverse stock split of Synta's issued and outstanding shares of common stock, in the form attached as Annex C to the accompanying proxy statement, pursuant to which any whole number of outstanding shares between and including twenty (20) and thirty-five (35), such whole number to be determined by the Synta board of directors, would be combined and reclassified into one share of Synta common stock;

 

 

3.

 

To approve an amendment to the 2015 Stock Plan to increase the total number of shares of Synta common stock currently available for issuance under the 2015 Stock Plan by 40,000,000 shares, prior to giving effect to the proposed reverse stock split, in the form attached as Annex D to the accompanying proxy statement;

 

 

4.

 

To elect one Class III director to Synta's board of directors for a term of three years (provided, however, that if the merger is completed, the board of directors will be reconstituted as provided in the Merger Agreement);

 

 

5.

 

To approve, on an advisory basis, the compensation of Synta's named executive officers as disclosed in the accompanying proxy statement, pursuant to the compensation disclosure rules of the Securities and Exchange Commission;

 

 

6.

 

To approve, on an advisory basis, the golden parachute compensation that may be paid or become payable to Synta's named executive officers as disclosed in the accompanying proxy statement;

 

 

7.

 

To ratify the appointment of Ernst & Young LLP as Synta's independent registered public accounting firm for the fiscal year ending December 31, 2016;

 

 

8.

 

To consider and vote on a proposal to adjourn the Annual Meeting, if necessary, to solicit additional proxies, in the event that there are not sufficient votes at the time of the Annual Meeting to approve Proposal Nos. 1, 2 and 3; and

 

 

9.

 

To consider any other business that is properly brought before the meeting and any adjournments or postponements thereof.

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Record Date:   The board of directors has fixed the close of business on [·], 2016 as the record date for determining stockholders entitled to notice of and to vote at the meeting. Only holders of record of shares of Synta common stock at the close of business on the record date are entitled to notice of, and to vote at, the Annual Meeting. At the close of business on the record date, Synta had [·] shares of common stock outstanding and entitled to vote.

        Even if you plan to attend the Annual Meeting in person, Synta requests that you please sign and return the enclosed proxy to ensure that your shares will be represented at the Annual Meeting if you are unable to attend. You may change or revoke your proxy at any time before it is voted at the meeting.

        THE SYNTA BOARD OF DIRECTORS HAS DETERMINED AND BELIEVES THAT EACH OF THE PROPOSALS OUTLINED ABOVE IS ADVISABLE TO, AND IN THE BEST INTERESTS OF, SYNTA AND ITS STOCKHOLDERS AND HAS APPROVED EACH PROPOSAL. THE SYNTA BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS THAT SYNTA STOCKHOLDERS VOTE "FOR" EACH PROPOSAL.

    By Order of the Synta Board of Directors,

 

 

Wendy E. Rieder, Esq.
Senior Vice President, General Counsel and Secretary
Lexington, Massachusetts
[
·], 2016

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TABLE OF CONTENTS

 
  Page

QUESTIONS ABOUT THE MERGER

  2

SUMMARY

 
11

The Companies

  11

The Merger

  12

Reasons for the Merger

  12

Opinion of Roth Capital Partners, LLC as Synta's Financial Advisor

  12

Overview of the Merger Agreement

  13

Voting Agreements

  14

Lock-Up Agreements

  15

Management Following the Merger

  15

Interests of Certain Directors, Officers and Affiliates of Synta

  15

Material U.S. Federal Income Tax Consequences of the Merger

  17

Risk Factors

  17

Regulatory Approvals

  18

NASDAQ Stock Market Listing

  18

Anticipated Accounting Treatment

  18

Appraisal Rights and Dissenters' Rights

  18

SELECTED HISTORICAL AND UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL DATA

 
19

Selected Historical Financial Data of Synta

  19

Selected Historical Financial Data of Madrigal

  20

Selected Unaudited Pro Forma Condensed Combined Financial Data of Synta and Madrigal

  21

Comparative Historical and Unaudited Pro Forma Per Share Data

  22

MARKET PRICE AND DIVIDEND INFORMATION

 
24

RISK FACTORS

 
26

Risks Related to the Merger

  26

Risks Related to the Proposed Reverse Stock Split

  32

Risks Related to Synta

  33

Risks Related to Synta's Common Stock

  33

Risks Related to Madrigal's Business

  36

Risks Related to Madrigal's Intellectual Property

  47

Risks Related to Madrigal's Development, Commercialization and Regulatory Approval

  50

Risks Related to Madrigal's Reliance on Third Parties

  53

Risks Related to the Combined Company

  55

FORWARD-LOOKING STATEMENTS

 
61

THE ANNUAL MEETING OF SYNTA STOCKHOLDERS

 
62

Date, Time and Place

  62

Purposes of the Synta Annual Meeting

  62

Recommendation of the Synta Board of Directors

  63

Record Date and Voting Power

  64

Voting and Revocation of Proxies

  64

Required Vote

  65

Solicitation of Proxies

  66

Other Matters

  66

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  Page

THE MERGER

  67

Background of the Merger

  67

Reasons for the Merger

  75

Opinion of Roth Capital Partners, LLC as Synta's Financial Advisor

  78

MTS Health Partners Fees

  89

Interests of the Synta Directors and Executive Officers in the Merger

  89

Golden Parachute Compensation

  91

Limitations of Liability and Indemnification of the Synta and Madrigal Officers and Directors

  94

Stock Options

  95

Merger Consideration and Adjustment

  95

Effective Time of the Merger

  96

Regulatory Approvals

  96

Tax Treatment of the Merger

  96

NASDAQ Stock Market Listing

  96

Anticipated Accounting Treatment

  97

THE MERGER AGREEMENT

 
98

General

  98

Structure

  98

Completion and Effectiveness of the Merger

  98

Merger Consideration

  98

Synta Stock and Options

  99

Procedures for Exchanging Madrigal Stock Certificates

  99

Fractional Shares

  99

Representations and Warranties

  100

Covenants; Conduct of Business Pending the Merger

  103

No Solicitation

  104

Disclosure Documents

  107

Resale Registration Statement

  107

Meeting of Synta's Stockholders

  107

Regulatory Approvals

  108

Indemnification of Officers and Directors

  108

Additional Agreements

  108

NASDAQ Stock Market LLC Listing

  109

Directors and Officers of Synta Following the Merger

  109

Conditions to Completion of the Merger

  109

Determination of Synta's Net Cash

  111

Termination of the Merger Agreement and Termination Fee

  112

Amendment

  113

Expenses

  113

AGREEMENTS RELATED TO THE MERGER

 
114

Madrigal Private Placement

  114

Voting Agreements

  114

Lock-Up Agreements

  115

SYNTA DIRECTORS, EXECUTIVE OFFICERS AND CORPORATE GOVERNANCE

 
116

The Board of Directors

  116

Director Independence

  119

Committees of the Board of Directors and Meetings

  119

Board Leadership Structure

  123

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  Page

Our Board of Directors' Role in Risk Oversight

  123

Stockholder Communications to the Board

  123

Executive Officers

  124

SYNTA EXECUTIVE OFFICER AND DIRECTOR COMPENSATION

 
126

Compensation Discussion and Analysis

  126

Summary Compensation Table

  136

Fiscal Year 2015 Grants of Plan-Based Awards

  138

Outstanding Equity Awards at 2015 Fiscal Year-End

  141

Option Exercises and Stock Vested in 2015

  143

Pension Benefits

  143

Nonqualified Deferred Compensation

  143

Potential Payments Upon Termination or Change of Control

  143

Director Compensation

  148

Compensation Committee Report

  152

EQUITY COMPENSATION PLAN INFORMATION

 
153

MATTERS BEING SUBMITTED TO A VOTE OF SYNTA STOCKHOLDERS

 
154

Proposal No. 1: Approval of the Merger, the Merger Agreement and the Issuance of Common Stock in the Merger

 
154

Proposal No. 2: Approval of the Amendment to the Certificate of Incorporation of Synta to Effect a Reverse Stock Split

  155

Proposal No. 3: Approval of Amendment to 2015 Stock Plan

  163

Proposal No. 4: Election of Synta Directors

  172

Proposal No. 5: Advisory Vote on Approval of Executive Compensation as Disclosed in this Proxy Statement

  173

Proposal No. 6: Advisory Vote on Golden Parachute Compensation

  174

Proposal No. 7: Ratification of Appointment of Independent Registered Public Accounting Firm

  175

Proposal No. 8: Approval of Possible Adjournment of the Synta Annual Meeting

  178

SYNTA BUSINESS

 
179

Overview

  179

Other Programs

  182

Manufacturing and Supply

  182

Competition

  182

Patents and Proprietary Rights

  182

Government Regulation

  182

Employees

  182

Properties

  183

MADRIGAL BUSINESS

 
184

Overview

  184

Lead Product Candidate—MGL-3196

  185

MGL-3196 Clinical and Non-Clinical Development Program

  186

Target Indications

  187

Collaborations

  191

Competition

  191

Sales and Marketing

  192

Manufacturing

  193

Employees

  193

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  Page

Intellectual Property

  193

Orphan Drug Designation

  194

Government Regulation

  194

General Corporate Information

  202

SYNTA MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

 
203

QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK OF SYNTA

 
204

MADRIGAL MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

 
205

Overview

  205

Recent Developments

  205

Basis of Presentation

  206

Critical Accounting Policies and Significant Judgments and Estimates

  208

Results of Operations

  209

Liquidity and Capital Resources

  211

Contractual Obligations and Commitments

  213

Quantitative and Qualitative Disclosures about the Market Risk of Madrigal

  214

MANAGEMENT FOLLOWING THE MERGER

 
215

Executive Officers and Directors

  215

Controlled Company

  217

Board of Directors of the Combined Company Following the Merger

  217

Employment Arrangements with Dr. Friedman and Dr. Taub

  220

RELATED PARTY TRANSACTIONS OF DIRECTORS AND EXECUTIVE OFFICERS OF THE COMBINED COMPANY

 
222

Synta Transactions

  222

Madrigal Transactions

  223

Madrigal Private Placement in Connection with Merger

  223

Madrigal Change in Control Bonus Plan

  224

UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL STATEMENTS

 
226

Unaudited Pro Forma Condensed Combined Balance Sheet

  228

Unaudited Pro Forma Condensed Combined Statement of Operations

  229

Unaudited Pro Forma Condensed Combined Statement of Operations

  229

Notes to the Unaudited Pro Forma Condensed Combined Financial Information

  230

DESCRIPTION OF SYNTA CAPITAL STOCK

 
235

Description of Common Stock

  235

Transfer Agent and Registrar

  235

NASDAQ Global Market

  235

Description of Preferred Stock

  235

Anti-Takeover Provisions of our Certificate of Incorporation and Bylaws

  236

Provisions of Delaware Law Governing Business Combinations

  237

PRINCIPAL STOCKHOLDERS OF SYNTA

 
238

PRINCIPAL STOCKHOLDERS OF MADRIGAL

 
241

PRINCIPAL STOCKHOLDERS OF COMBINED COMPANY

 
243

OTHER MATTERS

 
246

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  Page

WHERE YOU CAN FIND MORE INFORMATION

  246

TRADEMARK NOTICE

 
247

INDEX TO MADRIGAL FINANCIAL STATEMENTS

 
F-1

ANNEX A—AGREEMENT AND PLAN OF MERGER

 
A-1

ANNEX B—OPINION LETTER OF ROTH CAPITAL PARTNERS, LLC

 
B-1

ANNEX C—FORM OF CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF SYNTA PHARMACEUTICALS

 
C-1

ANNEX D—AMENDED 2015 STOCK PLAN

 
D-1

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SYNTA PHARMACEUTICALS CORP.
PROXY STATEMENT FOR 2016 ANNUAL MEETING OF STOCKHOLDERS

ABOUT THIS DOCUMENT

        Synta Pharmaceuticals Corp., which we refer to herein as the "Company," "Synta," "we," "our," or "us," is providing these proxy materials in connection with the solicitation by our board of directors of proxies to be voted at our annual meeting of stockholders to be held at [·], local time, on [·], [·], 2016, at the offices of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., One Financial Center, Boston, MA 02111, or at any adjournment or postponement thereof, or Annual Meeting. This proxy statement and the enclosed proxy card will be mailed to each stockholder entitled to notice of, and to vote at, the Annual Meeting commencing on or about [·], 2016.

        You should rely only on the information contained in or incorporated by reference into this proxy statement. No one has been authorized to provide you with information that is different from that contained in or incorporated by reference into this proxy statement. This proxy statement is dated [·], 2016. You should not assume that the information contained in this proxy statement is accurate as of any other date, nor should you assume that the information incorporated by reference into this proxy statement is accurate as of any date other than the date of such incorporated document. The mailing of this proxy statement to our stockholders will not create any implication to the contrary.

        Except where specifically noted, the following information and all other information contained in this proxy statement does not give effect to the proposed reverse stock split described in Proposal No. 2, beginning on page 155 in this proxy statement.

        This proxy statement does not constitute an offer to sell, or a solicitation of an offer to buy, any securities, or the solicitation of a proxy, in any jurisdiction in which or from any person to whom it is unlawful to make any such offer or solicitation in such jurisdiction.


REFERENCES TO ADDITIONAL INFORMATION

        This proxy statement incorporates important business and financial information about Synta that is not included in or delivered with this document. You may obtain this information without charge through the Securities and Exchange Commission (the "SEC") website (www.sec.gov) or upon your written or oral request by contacting the Wendy E. Rieder, Senior Vice President, General Counsel of Synta Pharmaceuticals Corp., 125 Hartwell Avenue, Lexington, MA 02421 or by calling (781) 274-8200.

        You may also request information from The Proxy Advisory Group, LLC, Synta's proxy solicitor, at the following address and telephone number:

The Proxy Advisory Group, LLC
Shareholders Call Toll Free: (888) 337-7699, or 888-33PROXY

        For additional details about where you can find information about Synta, please see the section entitled "Where You Can Find More Information" in this proxy statement.

1


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QUESTIONS AND ANSWERS ABOUT THE MERGER

        Except where specifically noted, the following information and all other information contained in this proxy statement does not give effect to the proposed reverse stock split described in Proposal No. 2, beginning on page 155 of this proxy statement.

        The following section provides answers to frequently asked questions about the merger. This section, however, provides only summary information. Please refer to the more detailed information contained elsewhere in this proxy statement and the annexes to and the documents referred to or incorporated by references in this proxy statement.

Q.
Why am I receiving this proxy statement?

A:
You are receiving this proxy statement because you have been identified as a stockholder of Synta as of the record date for the 2016 annual meeting of stockholders, or the Annual Meeting. You are being asked to vote at the Annual Meeting to approve, among other things, the issuance of shares of Synta common stock as contemplated by the Merger Agreement. This document serves as a proxy statement of Synta used to solicit proxies for the Annual Meeting.

Q:
What is the merger?

A:
Synta and Madrigal Pharmaceuticals, Inc., or Madrigal, have entered into an Agreement and Plan of Merger and Reorganization, dated as of April 13, 2016, which we refer to as the Merger Agreement. The Merger Agreement contains the terms and conditions of the proposed business combination of Synta and Madrigal. Under the Merger Agreement, Saffron Merger Sub, Inc., a wholly-owned subsidiary of Synta, or Saffron Merger Sub, will merge with and into Madrigal, with Madrigal surviving as a wholly-owned subsidiary of Synta. Thereafter, Synta will change its corporate name to "Madrigal Pharmaceuticals, Inc." as required by the Merger Agreement. This transaction is referred to as "the merger."
Q:
What will happen to Synta if, for any reason, the merger does not close?

A:
If, for any reason, the merger does not close, the Synta board of directors may elect to, among other things, attempt to complete another strategic transaction like the merger, attempt to sell or

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Q:
Why are the two companies proposing to merge?

A:
Madrigal and Synta believe that the merger will result in a financially strong pharmaceutical company focused on the development of novel small-molecule drugs addressing major unmet needs in cardiovascular, metabolic and liver diseases. Madrigal and Synta expect that the combined company will have the resources to fund the development of MGL-3196, a Phase 2-ready, once-daily, oral, liver-directed, selective thyroid hormone receptor-ß, or THR-ß, agonist for the treatment of non-alcoholic steatohepatitis, or NASH, heterozygous familial hypercholesterolemia, or HeFH, and homozygous familial hypercholesterolemia, or HoFH, through Phase 2 clinical studies in NASH, HeFH and HoFH. For a discussion of Synta's reasons for the merger, please see the sections entitled "The Merger—Background of the Merger" beginning on page 67 and "The Merger—Reasons for the Merger" beginning on page 75.

Q:
How much cash will Synta have at the closing of the merger?

A:
It is a closing condition of the Merger Agreement that Synta have net cash of at least $28.5 million at the closing of the merger. The actual amount of net cash will depend mostly on the timing of the closing.

Q:
What is required to complete the merger?

A:
To complete the merger, Synta stockholders must approve the issuance of Synta common stock to Madrigal securityholders by virtue of the merger as contemplated by the Merger Agreement and the amendment to the restated certificate of incorporation of Synta effecting the reverse stock split.

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Q:
Are there any federal or state regulatory requirements that must be complied with or federal or state regulatory approvals or clearances that must be obtained in connection with the merger?

A:
Neither Synta nor Madrigal is required to make any filings or obtain any approvals or clearances from any antitrust regulatory authorities in the United States or other countries to consummate the merger. In the United States, Synta must comply with applicable federal and state securities laws and The NASDAQ Stock Market's rules and regulations in connection with the issuance of the shares in connection with the merger, including the filing with the SEC, of this proxy statement. Prior to consummation of the merger, the parties intend to file an initial listing application with The NASDAQ Global Market or The NASDAQ Capital Market pursuant to The NASDAQ Stock Market's "change of control" rules and to effect the initial listing of Synta's common stock issuable in connection with the merger.

Q:
Will holders of the Synta common shares issued in the merger be able to trade those shares?

A:
The shares of Synta common stock issued as consideration in the merger will be issued in transactions exempt from registration under the Securities Act of 1933 as amended, or the Securities Act, in reliance on Section 4(a)(2) of the Securities Act, and Regulation D promulgated thereunder and may not be offered or sold by the holders of those shares absent registration or an applicable exemption from registration requirements. As a general matter, holders of such shares will not be able to transfer any of their shares until at least six months after receiving shares of Synta common stock, which is when the shares would first be eligible to be sold under Rule 144 promulgated under the Securities Act, assuming the conditions thereof are otherwise satisfied. In connection with the merger, however, Synta has agreed to file with the SEC a registration statement on Form S-3 to register the shares of Synta common stock received in the merger for resale in the public markets. Upon such registration statement being declared effective by the SEC, such shares shall become freely tradeable subject to certain limitations for stockholders deemed to be affiliates of the combined company.
Q:
Who will be the directors of Synta following the completion of the merger?

A:
The combined company's board of directors will initially be fixed at seven members, consisting of (i) one member designated by Synta, Keith R. Gollust, the current Chairman of the board of directors of Synta, (ii) one member to be mutually agreed upon by Synta and Madrigal meeting the SEC and NASDAQ Stock Market independence requirements, and (iii) five members designated by Madrigal, namely Paul A. Friedman, M.D., who will be the Chairman, Rebecca Taub, M.D., Fred Craves, Ph.D., who will be the lead director and who currently is the founder

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Q:
Who will be the executive officers of Synta immediately following the completion of the merger?

A:
Immediately following the completion of the merger, the executive management team of Synta is expected to be composed of Paul A. Friedman, M.D., serving as the Chief Executive Officer and Chairman of the Board of the combined company, Rebecca Taub, M.D., serving as Chief Medical Officer, Executive Vice President, Research & Development and Director of the combined company, and Marc R. Schneebaum serving as Chief Financial Officer of the combined company.

Q:
Am I entitled to appraisal rights?

A:
Holders of Synta common stock are not entitled to appraisal rights in connection with the merger.

Q:
Have Madrigal's stockholders adopted the Merger Agreement and approved the merger?

A:
Yes. On April 13, 2016, all of Madrigal's stockholders adopted the Merger Agreement and approved the merger and related transactions. Accordingly, no appraisal rights are available to Madrigal stockholders in connection with this transaction.

Q:
What are the material U.S. federal income tax consequences of the merger to Synta stockholders?

A:
Each of Synta and Madrigal intends the merger to qualify as a reorganization within the meaning of Section 368(a) of the Internal Revenue Code of 1986, as amended, or the Code. Since Synta stockholders will continue to own and hold their existing shares of Synta common stock following the merger, the merger generally will not result in U.S. federal income tax consequences to Synta stockholders.
Q:
Do persons involved in the merger have interests that may conflict with mine as a Synta stockholder?

A:
Yes. When considering the recommendation of the Synta board of directors, you should be aware that certain members of the Synta board of directors and named executive officers of Synta have interests in the merger that may be different from, or in addition to, interests they may have as

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Q:
Why is Synta seeking stockholder approval of the merger and the issuance of shares of common stock issuable upon the merger?

A:
Because our common stock is listed on The NASDAQ Global Market, we are subject to The NASDAQ Stock Market Listing Rules. Rule 5635(a) of The NASDAQ Stock Market listing standards requires stockholder approval with respect to issuances of Synta common stock, among other instances, when the shares to be issued are being issued in connection with the acquisition of the stock of another company and are equal to 20% or more of Synta's outstanding common stock before the issuance. Rule 5635(b) of the The NASDAQ Stock Market listing standards requires stockholder approval when any issuance or potential issuance will result in a change of control of the issuer. Although The NASDAQ Stock Market has not adopted any rule on what constitutes a "change of control" for purposes of Rule 5635(b), The NASDAQ Stock Market has previously indicated that the acquisition of, or right to acquire, by a single investor or affiliated investor group, as little as 20% of the common stock (or securities convertible into or exercisable for common stock) or voting power of an issuer could constitute a change of control.
Q:
As a Synta stockholder, how does the Synta board of directors recommend that I vote?

A:
After careful consideration, the Synta board of directors unanimously recommends that Synta stockholders vote "FOR" Proposal Nos. 1 through 8. For a detailed description of each of Proposal Nos. 1 through 8, see the section entitled "Matters Being Submitted to a Vote of Synta Stockholders" beginning on page 154.

Q:
What risks should I consider in deciding whether to vote in favor of the merger?

A:
You should carefully review the section of this proxy statement entitled "Risk Factors," beginning on page 26, which sets forth certain risks and uncertainties related to the merger, risks and uncertainties to which the combined company's business will be subject, and risks and uncertainties to which each of Synta and Madrigal, as an independent company, is subject.

Q:
What is "golden parachute" compensation and why I am being asked to vote on it?

A:
The SEC has adopted rules that require Synta to seek an advisory (non-binding) vote on "golden parachute" compensation. "Golden parachute" compensation is compensation that is tied to or based on the merger and that will or may be paid by Synta to its named executive officers in connection with the merger.

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Q:
When do you expect the merger to be completed?

A:
Synta and Madrigal anticipate that the merger will occur soon after the Annual Meeting, which is expected to occur in the third quarter of 2016, but Synta cannot predict the exact timing. For more information, please see the section entitled "The Merger Agreement—Conditions to Completion of the Merger" beginning on page 109.

Q:
What do I need to do now?

A:
You are urged to read this proxy statement carefully, including its annexes, and to consider how the merger affects you.
Q:
What constitutes a quorum at the Annual Meeting?

A:
The presence at the Annual Meeting, in person or by proxy, of the holders of a majority of the shares of Synta common stock issued and outstanding on the record date for the Annual Meeting will constitute a quorum for the transaction of business at the Annual Meeting.

Q:
What happens if I abstain?

A:
Shares abstaining from voting on a matter will be counted for the purpose of determining whether a quorum exists for the Annual Meeting, but are treated as having not voted. Abstentions will have the same effect as voting against Proposal Nos. 1 and 2, but will have no impact on the outcome of the vote for Proposal Nos. 3, 4, 5, 6, 7 and 8.

Q:
If my Synta shares are held in "street name" by my broker, will my broker vote my shares for me?

A:
Unless your broker has discretionary authority to vote on certain matters, your broker will not be able to vote your shares of Synta common stock without instructions from you. Brokers are not expected to have discretionary authority to vote for Proposal Nos. 1, 3, 4, 5, 6 or 8. To make sure that your vote is counted, you should instruct your broker to vote your shares, following the procedures provided by your broker.

Q.
How Do I Vote?

A.
Whether you plan to attend the Annual Meeting or not, we urge you to vote by proxy. All shares represented by valid proxies that we receive through this solicitation, and that are not revoked, will be voted in accordance with your instructions on the proxy card or as instructed via Internet or telephone. You may specify whether your shares should be voted for the nominee for director and whether your shares should be voted for, against or to abstain with respect to each of the other proposals. If you properly submit a proxy without giving specific voting instructions, your shares will be voted in accordance with the board of directors' recommendations as noted below. Voting by proxy will not affect your right to attend the Annual Meeting. If your shares are registered directly in your name through our stock transfer agent, Computershare Trust Company, N.A., or you have stock certificates registered in your name, you may vote:

By mail.  If you received a proxy card by mail, you can vote by mail by completing, signing, dating and returning the proxy card as instructed on the card. Your proxy will be voted in accordance with your instructions. If you sign the proxy card but do not specify how you want your shares voted, they will be voted as recommended by our board of directors below.

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Q:
May I vote in person at the Annual Meeting?

A:
If your shares of Synta common stock are registered directly in your name with the Synta transfer agent, you are considered to be the stockholder of record with respect to those shares, and the proxy materials and proxy card are being sent directly to you by Synta. If you are a Synta stockholder of record, you may attend the Annual Meeting and vote your shares in person. Even if you plan to attend the Annual Meeting in person, Synta requests that you sign and return the enclosed proxy to ensure that your shares will be represented at the Annual Meeting if you are unable to attend. If your shares of Synta common stock are held in a brokerage account or by another nominee, you are considered the beneficial owner of shares held in "street name," and the proxy materials are being forwarded to you by your broker or other nominee together with a voting instruction card. As the beneficial owner, you are also invited to attend the Annual Meeting. Because a beneficial owner is not the stockholder of record, you may not vote these shares in person at the Annual Meeting unless you obtain a proxy from the broker, trustee or nominee that holds your shares, giving you the right to vote the shares at the meeting.

Q:
When and where is the Annual Meeting being held?

A:
The Annual Meeting will be held at the offices of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., One Financial Center, Boston, MA 02111, at [·], local time, on [·], 2016. Subject to space availability, all Synta stockholders as of the record date, or their duly appointed proxies, may attend the Annual Meeting.

Q:
May I change my vote after I have submitted a proxy or provided proxy instructions?

A:
Synta stockholders of record, other than those Synta stockholders who are parties to voting agreements, may revoke their proxy at any time before their proxy is voted at the Annual Meeting in one of three ways. First, a stockholder of record of Synta can send a written notice to the Secretary of Synta stating that it would like to revoke its proxy. Second, a stockholder of record of Synta can submit new proxy instructions on a new proxy card. Third, a stockholder of record of Synta can attend the Annual Meeting and vote in person. Attendance alone will not revoke a proxy. If a Synta stockholder of record or a stockholder who owns Synta shares in "street name" has instructed a broker to vote its shares of Synta common stock, the stockholder must follow directions received from its broker to change those instructions.

Q:
Who is paying for this proxy solicitation?

A:
Synta will bear its own expenses in printing and filing this proxy statement and the proxy card. Arrangements will also be made with brokerage firms and other custodians, nominees and fiduciaries who are record holders of Synta common stock for the forwarding of solicitation

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Q:
Who can help answer my questions?

A:
If you are a Synta stockholder and would like additional copies, without charge, of this proxy statement or if you have questions about the merger, including the procedures for voting your shares, you should contact:

Synta Pharmaceuticals Corp.
125 Hartwell Avenue
Lexington, MA 02421
Tel: (781) 274-8200
Attn: Wendy E. Rieder, Senior Vice President, General Counsel

The Proxy Advisory Group, LLC
Shareholders Call Toll Free: (888) 337-7699, or 888-33PROXY

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SUMMARY

        This summary highlights selected information from this proxy statement and may not contain all of the information that is important to you. To better understand the merger and the proposals being considered at the Annual Meeting, you should read this entire proxy statement carefully, including the Merger Agreement attached as Annex A, the opinion of Roth Capital Partners, LLC attached as Annex B and the other annexes to which you are referred herein. For more information, please see the section entitled "Where You Can Find More Information" beginning on page 246.

The Companies

Synta Pharmaceuticals Corp.

125 Hartwell Avenue
Lexington, MA 02421
(781) 274-8200

        Synta is a company that has been historically focused on research, development and commercialization of novel oncology medicines with the potential to change the lives of cancer patients. In October 2015, Synta announced the decision to terminate for futility the Phase 3 GALAXY-2 trial of its novel heat shock protein 90 (Hsp90) inhibitor, ganetespib, and docetaxel in the second-line treatment of patients with advanced non-small cell lung adenocarcinoma. Based on the review of a pre-planned interim analysis, the study's Independent Data Monitoring Committee (IDMC) concluded that the addition of ganetespib to docetaxel was unlikely to demonstrate a statistically significant improvement in overall survival, the primary endpoint of the study, compared to docetaxel alone. Synta continues to conduct limited activities with respect to ganetespib and the drug candidates from its proprietary Hsp90 inhibitor Drug Conjugate, or HDC program, including STA-12-8666.

Madrigal Pharmaceuticals, Inc.

500 Office Center Drive, Suite 400
Fort Washington, PA 19034
(610) 527-6790

        Madrigal is a clinical-stage biopharmaceutical company focused on the development and commercialization of innovative therapeutic candidates for the treatment of cardiovascular, metabolic and liver diseases. Madrigal's lead product candidate, MGL-3196, is a proprietary, liver-directed, selective thyroid hormone receptor-ß, or THR-ß, agonist that can potentially be used to treat a number of disease states with high unmet medical need. Madrigal is developing MGL-3196 for non-alcoholic steatohepatitis, or NASH, and is planning to conduct a Phase 2 clinical trial in this indication. Madrigal is also developing MGL-3196 for dyslipidemia, particularly genetic dyslipidemias such as familial hypercholesterolemia, or FH, including both homozygous and heterozygous forms of the disease. Madrigal is planning to conduct two Phase 2 clinical trials in FH, one in heterozygous FH patients and one a proof-of-concept clinical trial in homozygous FH patients. MGL-3196 is a once-daily oral pill that has been studied in three completed Phase 1 trials in a total of 115 subjects. MGL-3196 appeared to be safe and well-tolerated in these trials, which included a single ascending dose trial, a multiple ascending dose trial, and a drug interaction trial with a statin.

Saffron Merger Sub, Inc.

        Saffron Merger Sub, Inc., or Saffron Merger Sub, is a wholly-owned subsidiary of Synta, and was formed solely for the purposes of carrying out the merger.

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The Merger (see page 67)

        If the merger is completed, Saffron Merger Sub will merge with and into Madrigal, with Madrigal surviving as a wholly-owned subsidiary of Synta.

        At the effective time of the merger, each share of Madrigal common stock outstanding immediately prior to the effective time of the merger will be converted into the right to receive 5.5740 shares of Synta common stock, subject to adjustment to account for the reverse stock split to be implemented prior to the closing of the merger.

        Following the completion of the transactions contemplated by the Merger Agreement, the current securityholders of Madrigal and current equityholders of Synta are expected to own 64% and 36% of the combined company, respectively. This calculation does not contemplate outstanding Synta option awards, which will remain outstanding under their existing terms following the merger, nor does it include equity awards in the amount of 20,825,936 shares of common stock of the combined company that are expected to be granted immediately after the completion of the merger to Paul A. Friedman, M.D., and Rebecca Taub, M.D., as executive officers of the combined company.

        Each share of Synta common stock issued and outstanding at the time of the merger will remain issued and outstanding and those shares will be unaffected by the merger. Synta stock options and other equity awards that are outstanding immediately prior to the effective time of the merger will also remain outstanding and be unaffected by the merger. Please see "The Merger—Stock Options" beginning on page 95.

        The merger will be completed as promptly as practicable after all of the conditions to completion of the merger are satisfied or waived, including the approval of the stockholders of Synta. Synta and Madrigal are working to complete the merger as quickly as practicable and expect that the merger will be completed during the third quarter of 2016. However, Synta and Madrigal cannot predict the exact timing of the completion of the merger because it is subject to various conditions. After completion of the merger, Synta will be renamed "Madrigal Pharmaceuticals, Inc."

Reasons for the Merger (see pages 67 and 75)

        Synta's board of directors considered numerous factors in reaching its conclusion to approve the merger and to recommend that the Synta stockholders approve the issuance of shares of Synta common stock in the merger, including those discussed under the sections entitled "The Merger—Background of the Merger" beginning on page 67 and "The Merger—Reasons for the Merger" beginning on page 75 of this proxy statement.

Opinion of Roth Capital Partners, LLC as Synta's Financial Advisor (see page 78)

        Roth Capital Partners, LLC, or Roth, the financial advisor of Synta, delivered to the board of directors of Synta a written opinion dated April 13, 2016, addressed to the board of directors of Synta, as of that date and subject to and based on the assumptions made, procedures followed, matters considered, limitations of the review undertaken and qualifications contained in the written opinion, as to the fairness, from a financial point of view, to Synta of the merger consideration to be paid by Synta in the merger pursuant to the Merger Agreement. The full text of this written opinion provided to the Synta board of directors, which describes, among other things, the assumptions made, procedures followed, factors considered, qualifications and limitations on the review undertaken, is attached as Annex B to this proxy statement and is incorporated by reference in its entirety. Holders of Synta common stock are encouraged to read the opinion carefully in its entirety. The Roth opinion was provided to the board of directors of Synta in connection with its evaluation of the consideration provided for in the merger. It does not address any other aspect of the merger or any alternative to the

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merger and does not constitute a recommendation as to how any stockholders of Synta should vote or act in connection with the merger or otherwise.

Overview of the Merger Agreement

Merger Consideration (see page 98)

        At the effective time of the merger each outstanding share of common stock of Madrigal immediately prior to the effective time of the merger will automatically be converted into the right to receive 5.5740 shares of Synta common stock, subject to adjustment to account for the reverse stock split to be implemented prior to the closing of the merger.

        As a result, following the completion of the merger, Madrigal's current securityholders would own in the aggregate approximately 64% of the combined company's outstanding common stock (with Bay City Capital and its affiliates, Madrigal's largest securityholder, owning approximately 52.5% of the combined company's outstanding shares of common stock) and Synta's equityholders would own in the aggregate approximately 36% of the combined company's outstanding common stock. This calculation does not contemplate outstanding Synta option awards, which will remain outstanding under their existing terms following the merger, nor does it include equity awards in the amount of 20,825,936 shares of common stock of the combined company that are expected to be granted immediately after the completion of the merger to Paul A. Friedman, M.D., and Rebecca Taub, M.D., as executive officers of the combined company.

        The Merger Agreement does not include a price-based termination right, so there will be no adjustment to the total number of shares of Synta common stock that Madrigal stockholders will be entitled to receive for changes in the market price of Synta common stock. Accordingly, the market value of the shares of Synta common stock issued pursuant to the merger will depend on the market value of the shares of Synta common stock at the time the merger closes, and could vary significantly from the market value on the date of this proxy statement.

Conditions to Completion of the Merger (see page 109)

        To complete the merger, Synta stockholders must approve the issuance of shares of Synta common stock to Madrigal stockholders by virtue of the merger and an amendment to the restated certificate of incorporation of Synta effecting the proposed reverse stock split. In addition to obtaining such stockholder approvals, each of the other closing conditions set forth in the Merger Agreement must be satisfied or waived.

No Solicitation (see page 104)

        The Merger Agreement contains provisions prohibiting Synta and Madrigal from seeking a competing transaction, subject to specified exceptions described in the Merger Agreement. Under these "no solicitation" provisions, each of Synta and Madrigal has agreed, subject to specified exceptions, that neither it nor its subsidiaries, nor any of its officers, directors, employees, representatives, affiliates, advisors or agents will directly or indirectly:

    initiate, solicit, seek or knowingly encourage or support any inquiries, proposals or offers that constitute or may reasonably be expected to lead to any competing proposal;

    engage or participate in, or knowingly facilitate, any discussions or negotiations regarding, or furnish any nonpublic information to any person in connection with, any inquiries, proposals or offers that constitute, or may reasonably be expected to lead to, a competing proposal;

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    enter into any letter of intent, agreement in principle or other similar type of agreement relating to a competing proposal, or enter into any agreement or agreement in principle requiring either Synta or Madrigal, as the case may be, to abandon, terminate or fail to complete the merger; or

    resolve, propose or agree to do any of the foregoing.

Termination of the Merger Agreement (see page 112)

        Either Synta or Madrigal can terminate the Merger Agreement under certain circumstances, which would prevent the merger from being completed.

Termination Fee (see page 112)

        The Merger Agreement provides that, upon termination of the Merger Agreement under specified circumstances, Synta may be required to pay Madrigal a termination fee of $1.25 million, or reimburse Madrigal for up to $250,000 in certain transaction-related expenses, or Madrigal may be required to pay Synta a termination fee of $1.0 million.

Madrigal Private Placement (see pages 114 and 223)

        On April 13, 2016, Madrigal entered into an amended and restated senior secured note purchase agreement, or the 2016 purchase agreement, with certain investors, including Bay City Capital, pursuant to which Madrigal agreed to issue, and the investors agreed to purchase, $9 million in aggregate principal amount of convertible notes before or concurrent with the completion of the merger, which we refer to as the new notes. The new notes bear interest at a rate of 8% per annum. Pursuant to the 2016 purchase agreement, Bay City Capital agreed to waive all accrued interest on the $36.9 million of convertible notes issued by Madrigal to Bay City Capital pursuant to (i) a note purchase agreement dated September 16, 2011 and (ii) an assignment and issuance agreement dated September 14, 2011, which we refer to as the old notes, through the date of the 2016 purchase agreement. Bay City Capital also agreed that no interest will accrue on the old notes from the date of the 2016 purchase agreement through the date on which either the merger is consummated or the Merger Agreement is terminated. The other investor parties to the 2016 purchase agreement also agreed that no interest will accrue on the new notes issued thereunder from the date of the 2016 purchase agreement through the date on which either the merger is consummated or the Merger Agreement is terminated. In addition, all of the old notes and new notes will convert into common stock of Madrigal pursuant to their terms immediately prior to completion of the merger. The 2016 purchase agreement and accompanying new notes contain customary events of default, which, if uncured, entitle each noteholder to accelerate the due date of the unpaid principal amount of, and all accrued and unpaid interest on, the new notes.

Voting Agreements (see page 114)

        In connection with the execution of the Merger Agreement, certain securityholders of Madrigal entered into voting agreements with Synta and Madrigal under which such securityholders have agreed to vote in favor of the merger and against any alternative acquisition proposal, agreement or transaction. As of May 2, 2016, these individuals and entities own in the aggregate, approximately 100% of the voting power of Madrigal on an as-converted to common stock basis. These voting agreements grant Synta irrevocable proxies to vote or give consent with respect to any shares of Madrigal stock over which such securityholder has voting power in favor of each of the Madrigal proposals described elsewhere in this proxy statement and against any alternative acquisition proposal, agreement or transaction. The stockholders of Madrigal approved the merger on April 13, 2016.

        In connection with the execution of the Merger Agreement, certain stockholders of Synta, who in the aggregate, own approximately 18.2% of Synta's outstanding shares, also entered into voting agreements with Synta and Madrigal under which such stockholder has agreed to vote in favor of the

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proposals that relate to the merger described elsewhere in this proxy statement and against any alternative acquisition proposal, agreement or transaction. Each of these voting agreements grant Madrigal irrevocable proxies to vote any shares of Synta common stock over which such stockholder has voting power in favor of each of the proposals described elsewhere in this proxy statement and against any alternative acquisition proposal, agreement or transaction.

        Each stockholder executing a voting agreement has made representations and warranties to Synta and Madrigal, as applicable, regarding ownership and unencumbered title to the shares thereto, such stockholder's power and authority to execute the voting agreement, and due execution and enforceability of the voting agreement. Unless otherwise waived, all of these voting agreements prohibit the sale, assignment, transfer or other disposition by the stockholder of their respective shares of Synta or Madrigal stock, or the entrance into an agreement or commitment to do any of the foregoing, except for transfers by will or by operation of law, in which case the voting agreement will bind the transferee. Each stockholder executing a voting agreement has also waived its statutory appraisal rights in connection with the merger.

        The voting agreements will terminate at the earlier of the effective time of the merger, termination of the Merger Agreement in accordance with its terms or upon mutual written consent of such stockholder, Synta and Madrigal.

Lock-Up Agreements (see page 115)

        As a condition to the closing of the merger, the Madrigal securityholders who entered into voting agreements also entered into lock-up agreements, pursuant to which the securityholders have agreed not to, except in limited circumstances, sell, assign, transfer, tender, or otherwise dispose of, any Madrigal securities and shares of Synta common stock, including, as applicable, shares received in the merger and issuable upon exercise of certain options, from April 13, 2016, the date the lock-up agreements were executed, until 180 days after the closing date of the merger.

        The Madrigal securityholders who have executed lock-up agreements own in the aggregate approximately 100% of the outstanding shares of Madrigal stock on an as-converted to common stock basis.

Management Following the Merger (see page 215)

        Effective as of the closing of the merger, Synta's executive officers are expected to be composed of Paul A. Friedman, M.D., serving as the Chief Executive Officer and Chairman of the Board, Rebecca Taub, M.D., serving as the Chief Medical Officer, Executive Vice President, Research & Development, and Marc R. Schneebaum, serving as Chief Financial Officer.

Interests of Certain Directors, Officers and Affiliates of Synta (see pages 89 and 222)

        In considering the recommendation of the Synta board of directors with respect to issuing shares of Synta common stock pursuant to the Merger Agreement and the other matters to be acted upon by Synta stockholders at the Annual Meeting, Synta stockholders should be aware that certain members of the Synta board of directors and named executive officers of Synta have interests in the merger that may be different from, or in addition to, interests they have as Synta stockholders. The Synta board of directors was aware of the following interests and considered them, among other matters, in its decision to approve the Merger Agreement.

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    Continued Service with Combined Company

      At the effective time of the merger, the officers of the combined company will include:

      Paul A. Friedman, M.D., a director of Synta from March 2014 until his resignation on April 13, 2016 concurrent with the announcement of the merger with Madrigal, who will be the Chief Executive Officer and Chairman of the combined company;

      Rebecca Taub, M.D., a current executive officer of Madrigal who will be the Chief Medical Officer, Executive Vice President, Research & Development and Director, of the combined company; and

      Marc R. Schneebaum, the current Chief Financial Officer of Synta, who will continue as the Chief Financial Officer of the combined company.

      Additionally, Keith R. Gollust, currently a director of Synta, will continue as a director of the combined company after the effective time of the merger.

    Synta Director Paul A. Friedman's Relationship with Madrigal and the Combined Company

      Dr. Friedman has personal interests both in Madrigal and the combined company. These interests were fully disclosed to and known by the Synta board of directors and corporate governance measures were taken to address them, including Dr. Friedman's exclusion from Synta board of director proceedings with respect to Madrigal, as described more fully in "The Merger—Background of the Merger." These interests are:

      The current Chief Executive Officer of Madrigal, Rebecca Taub, M.D. and Dr. Friedman are married.

      Upon the closing of the merger, Dr. Friedman and Dr. Taub will be employed as executive officers of the combined company as described above.

      Dr. Friedman and Dr. Taub have irrevocably committed to loan approximately $5 million to Madrigal in the form of promissory notes that will convert into 25,905,930 shares of Synta common stock as part of the merger closing.

      Dr. Friedman and Dr. Taub will have significant beneficial ownership interest in the combined company due in part to the post-closing entity's equity compensation arrangements with Dr. Friedman and Dr. Taub. Assuming the full vesting and exercise of options to purchase 14,875,669 shares of common stock and the vesting 5,950,267 shares of restricted stock, and based on the projected number of shares of Synta common stock to be outstanding immediately after the closing, Dr. Friedman and Dr. Taub would have a pro forma stock ownership of 60,493,023 shares of the combined company, or approximately 14.5% immediately after the closing of the merger.

    Other

    Upon a termination of employment in connection with the merger, Synta's named executive officers may receive cash severance payments and other benefits with a total value of approximately $3.2 million (collectively, not individually, and including the value of the accelerated vesting of unvested restricted stock awards and the vesting of restricted stock unit awards).

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Material U.S. Federal Income Tax Consequences of the Merger (see page 96)

        Each of Synta and Madrigal intends the merger to qualify as a reorganization within the meaning of Section 368(a) of the Internal Revenue Code of 1986, as amended, or the Code.

        Since Synta stockholders will continue to own and hold their existing shares of Synta common stock following the merger, the merger generally will not result in U.S. federal income tax consequences to Synta stockholders.

        Synta stockholders who are also stockholders of Madrigal should consult their tax advisor as to the tax consequences to them of participating in the merger as a Madrigal stockholder.

Risk Factors (see page 26)

        Both Synta and Madrigal are subject to various risks associated with their businesses and their industries. In addition, the merger, including the possibility that the merger may not be completed, poses a number of risks to each company and its respective stockholders, including the following risks:

    the market price of Synta common stock following the completion of the merger may decline as a result of the transaction;

    the anticipated benefits of the merger may not be realized;

    synta stockholders will have a reduced ownership and voting interest in, and will exercise less influence over the management of, the combined company following the completion of the merger;

    synta stockholders may not realize a benefit from the merger commensurate with the ownership dilution they will experience in connection with the merger;

    failure to complete the merger may adversely affect the common stock price of Synta and future business and operations of Synta and Madrigal;

    during the pendency of the merger, Synta and Madrigal may not be able to enter into a business combination with another party at a favorable price because of restrictions in the Merger Agreement, which could adversely affect their respective businesses;

    provisions of the Merger Agreement may discourage third parties from submitting alternative acquisition proposals, including proposals that may be superior to the merger;

    the lack of a public market for Madrigal shares makes it difficult to determine the fair value of Madrigal, and the merger consideration to be issued to Madrigal securityholders may exceed the actual value of Madrigal;

    synta and Madrigal will incur substantial transaction-related costs in connection with the merger;

    a failure by Synta to comply with the continued and initial listing standards of The NASDAQ Global Market or The NASDAQ Capital Market may subject its stock to delisting from The NASDAQ Stock Market, which listing is a condition to the completion of the merger;

    synta and Madrigal may become involved in securities class action litigation or shareholder derivative litigation that could divert management's attention and harm the combined company's business and insurance coverage may not be sufficient to cover all costs and damages;

    synta may not be able to complete the merger and may elect to pursue another strategic transaction similar to the merger, which may not occur on commercially reasonably terms or at all;

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    if the merger is not completed, Synta may elect to liquidate its remaining assets, and there can be no assurances as to the amount of cash available to distribute to stockholders after paying its debts and other obligations; and

    if the merger is not completed, and Synta fails to advance STA-12-8666 or acquire or develop other products or product candidates on commercially reasonable terms, or at all, Synta may be unable to conduct a viable operating business.

        These risks and other risks are discussed in greater detail under the section entitled "Risk Factors" beginning on page 26. Synta and Madrigal both encourage you to read and consider all of these risks carefully.

Regulatory Approvals (see page 108)

        Synta must comply with applicable federal and state securities laws and the rules and regulations of The NASDAQ Global Market in connection with the issuance of shares of Synta common stock and the filing of this proxy statement with the SEC.

NASDAQ Stock Market Listing (see pages 96 and 109)

        Prior to completion of the merger, Synta intends to file an initial listing application with The NASDAQ Global Market pursuant to The NASDAQ Stock Market's "change of control" rules. If such application is accepted, Synta anticipates that Synta's common stock will be listed on The NASDAQ Global Market or The NASDAQ Capital Market following the closing of the merger under the trading symbol "MDGL."

Anticipated Accounting Treatment (see page 97)

        Synta currently expects to treat the merger as a purchase by Madrigal of Synta under accounting principles generally accepted in the United States, or GAAP. Under the purchase method of accounting, the assets and liabilities of Synta will be recorded, as of the completion of the merger, at their respective fair values, in the financial statements of Madrigal. The financial statements of Madrigal issued after the completion of the merger will reflect these values, but will not be restated retroactively to reflect the historical financial position or results of operations of Synta.

Appraisal Rights and Dissenters' Rights

        Holders of Synta common stock are not entitled to appraisal rights in connection with the merger.

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SELECTED HISTORICAL AND UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL DATA

        The following tables present summary historical financial data for Synta and Madrigal, summary unaudited pro forma condensed combined financial data for Synta and Madrigal, and comparative historical and unaudited pro forma per share data for Synta and Madrigal. The following tables do not give effect to the proposed reverse stock split described in Proposal No. 2 of this proxy statement.

Selected Historical Financial Data of Synta

        The following table summarizes Synta's consolidated financial data as of the dates and for each of the periods indicated. The selected financial data as of December 31, 2015 and 2014 and for the years ended December 31, 2015, 2014 and 2013 are derived from the Synta audited consolidated financial statements and notes thereto appearing in Synta's Annual Report on Form 10-K for the year ended December 31, 2015, filed with the SEC on March 15, 2016 and amended April 29, 2016, or the Synta 10-K, which is incorporated by reference in this proxy statement. The selected financial data as of December 31, 2013, 2012, and 2011 and for the years ended December 31, 2012 and 2011 are derived from Synta's audited consolidated financial statements for the respective periods, which are not included or incorporated by reference in this proxy statement. The selected financial data as of March 31, 2016 and for the three months ended March 31, 2016 and 2015 are derived from the Synta unaudited financial statements and related notes appearing in Synta's Quarterly Report on Form 10-Q for the quarter ended March 31, 2016, filed with the SEC on May 10, 2016, or the Synta 10-Q, which is incorporated by reference in this proxy statement. This financial data should be read in conjunction with "Management's Discussion and Analysis of Financial Condition and Results of Operations" and the financial statements and notes thereto appearing in the Synta 10-K and the Synta 10-Q. Synta's historical results are not necessarily indicative of the results that may be expected in the future.

 
  Year ended December 31   Three Months Ended
March 31,
 
 
  2015   2014   2013   2012   2011   2016   2015  
 
  (in thousands, except per share data)
   
   
 

Consolidated Statement of Operations Data:

                                           

Revenues

                                           

License and milestone revenue(1)

  $   $   $   $   $ 6,731   $   $  

Grant revenue

                147     853          

Total revenues

                147     7,584          

Operating expenses:

                                           

Research and development

    54,218     68,205     71,860     49,412     41,464     3,407     16,182  

General and administrative

    13,392     15,746     15,699     11,676     11,552     3,040     4,150  

Total operating expenses

    67,610     83,951     87,559     61,088     53,016     6,447     20,332  

Loss from operations

    (67,610 )   (83,951 )   (87,559 )   (60,941 )   (45,432 )   (6,447 )   (20,332 )

Other expense, net

    (1,061 )   (2,210 )   (2,633 )   (1,849 )   (1,948 )   (77 )   (375 )

Net loss

  $ (68,671 ) $ (86,161 ) $ (90,192 ) $ (62,790 ) $ (47,380 )   (6,524 )   (20,707 )

Net loss per common share:

                                           

Basic and diluted net loss per common share

  $ (0.53 ) $ (0.87 ) $ (1.27 ) $ (1.06 ) $ (1.00 ) $ (0.05 ) $ (0.19 )

Basic and diluted weighted average number common shares outstanding

    128,595     98,489     70,977     59,411     47,198     137,362     108,376  

(1)
In December 2008, Synta entered into an agreement with Hoffman-La Roche, or Roche, for its CRACM inhibitor program. Roche provided written notification of termination in November 2011,

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    resulting in accelerated recognition of $2.1 million of previously deferred revenue in the fourth quarter of 2011.


 
   
   
   
   
   
  As of
Three Months
Ended
March 31,
2016
 
 
  Year ended December 31,  
 
  2015   2014   2013   2012   2011  
 
  (in thousands)
   
 

Consolidated Balance Sheet Data:

                                     

Cash, cash equivalents and marketable securities

  $ 66,574   $ 97,690   $ 91,476   $ 100,599   $ 39,725   $ 52,042  

Working capital

    49,987     68,457     60,034     77,899     25,138     43,957  

Total assets

    68,195     100,675     95,203     103,017     42,324     52,970  

Capital lease obligations, net of current portion

   
   
43
   
85
   
1
   
14
   
33
 

Term loans, current portion

    4,607     9,214     9,451     7,924     4,234     2,299  

Term loans, net of current portion

        4,607     13,820     4,464     12,388      

Common stock and additional paid-in capital

    756,647     702,705     600,486     536,284     413,201     757,095  

Accumulated deficit

    (706,244 )   (637,573 )   (551,412 )   (461,220 )   (398,430 )   (712,768 )

Total stockholders' equity

   
50,407
   
65,136
   
49,091
   
75,066
   
14,774
   
44,331
 

Selected Historical Financial Data of Madrigal

        The following table summarizes Madrigal's selected financial data as of the dates and periods indicated. The selected financial data as of December 31, 2015 and 2014 and for the years ended December 31, 2015 and 2014 are derived from the Madrigal audited financial statements prepared using GAAP, which are included in this proxy statement. The audit report on the financial statements for the years ended December 31, 2015 and 2014, which appears elsewhere herein, includes an explanatory paragraph related to Madrigal's ability to continue as a going concern. The selected financial data as of March 31, 2016 and for the three months ended March 31, 2016 and 2015 are derived from Madrigal's unaudited financial statements and related notes, which are included in this proxy statement. The financial data should be read in conjunction with "Madrigal Management's Discussion and Analysis of Financial Condition and Results of Operations" beginning on page 205 and

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the Madrigal financial statements and related notes appearing elsewhere in this proxy statement. The historical results are not necessarily indicative of results to be expected in any future period.

 
  Three Months
Ended March 31,
  Year Ended
December 31,
 
 
  2016   2015   2015   2014  
 
  (In thousands,
except per share
data)

   
   
 

Statements of Operations Data:

                         

Operating expenses

                         

Research and development

  $ 516   $ 344   $ 2,427   $ 777  

General and administrative

    222     196     806     548  

Loss from operation

   
(738

)
 
(540

)
 
(3,233

)
 
(1,326

)

Interest expense, net

    (975 )   (843 )   (3,612 )   (3,166 )

Net loss

  $ (1,713 ) $ (1,382 ) $ (6,845 ) $ (4,492 )

Basic and diluted net loss per common share

  $ (1.55 ) $ (1.28 ) $ (6.38 ) $ (4.30 )

Basic and diluted weighted average number of common shares outstanding

    1,106     1,080     1,073     1,045  

 

 
  As of
Three Months
Ended
March 31,
2016
  Year Ended
December 31,
 
 
  2015   2014  

Balance Sheet Data:

                   

Cash

 
$

618
 
$

306
 
$

148
 

Total assets

    770     364     194  

Convertible promissory notes payable—related party

    50,315     48,595     42,193  

Total liabilities

    51,396     49,277     42,263  

Accumulated deficit

    (50,632 )   (48,920 )   (42,069 )

Total stockholders' deficit

    (50,626 )   (48,913 )   (42,069 )

Selected Unaudited Pro Forma Condensed Combined Financial Data of Synta and Madrigal

        The following selected unaudited pro forma condensed combined financial data is intended to show how the merger might have affected historical financial statements. Synta and Madrigal unaudited pro forma condensed combined balance sheet data assume that the merger took place on March 31, 2016 and combine the Synta and Madrigal historical balance sheets at March 31, 2016. Synta and Madrigal unaudited pro forma condensed combined statement of operations data assume that the merger took place on each of January 1, 2016 and January 1, 2015, and combine the historical results of Synta and Madrigal for the three months ended March 31, 2016 and the year ended December 31, 2015. The following should be read in conjunction with the section entitled "Unaudited Pro Forma Condensed Combined Financial Statements" beginning on page 226, Synta's audited financial statements and notes thereto included in the Synta 10-K, Synta's unaudited financial statements and notes thereto included in the Synta 10-Q, Madrigal's audited and unaudited historical financial statements and the notes thereto beginning on page F-1, the sections entitled "Synta Management's Discussion and Analysis of Financial Condition and Results of Operations" beginning on page 203 and "Madrigal Management's Discussion and Analysis of Financial Condition and Results of Operations" beginning on page 205 and the other information contained in this proxy statement. The following information does not give effect to the proposed reverse stock split of Synta common stock described in Proposal No. 2.

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        The unaudited pro forma condensed combined financial statements were prepared in accordance with the regulations of the SEC. The pro forma adjustments reflecting the completion of the merger are based upon the application of the acquisition method of accounting in accordance with GAAP and upon the assumptions set forth in the unaudited pro forma condensed combined financial statements.

        The historical financial data has been adjusted to give pro forma effect to events that are (i) directly attributable to the merger, (ii) factually supportable and (iii) with respect to the statements of operations, expected to have a continuing impact on the combined results. The pro forma adjustments are preliminary and based on management's estimates of the fair value and useful lives of the assets acquired and liabilities assumed and have been prepared to illustrate the estimated effect of the acquisition and certain other adjustments.

        The unaudited pro forma condensed combined financial data is presented for illustrative purposes only and is not necessarily indicative of the financial condition or results of operations of future periods or the financial condition or results of operations that actually would have been realized had the entities been combined during the periods presented. In addition, as explained in more detail in the accompanying notes to the unaudited pro forma condensed combined financial statements (see the section entitled "Unaudited Pro Forma Condensed Combined Financial Statements" beginning on page 226), the preliminary acquisition-date fair value of the identifiable assets acquired and liabilities assumed reflected in the unaudited pro forma condensed combined financial statements is subject to adjustment and may vary from the actual amounts that will be recorded upon completion of the merger.

 
  Three Months
Ended
March 31,
2016
  Year Ended
December 31,
2015
 
 
  (in thousands except
per share amounts)

 

Unaudited Pro Forma Condensed Combined Statements of Operations Data:

             

Operating expenses:

             

Research and development

    4,137     57,501  

General and administrative

    3,230     15,958  

Total operating expenses

    7,367     73,459  

Net loss

  $ (7,444 ) $ (74,520 )

Basic and diluted net loss per share

  $ (0.02 ) $ (0.19 )

 

 
  As of
March 31,
2016
 
 
  (In thousands)
 

Unaudited Pro Forma Condensed Combined Balance Sheet Data:

       

Cash, cash equivalents and marketable securities

  $ 60,410  

Working capital

    45,582  

Total assets

    79,161  

Term loans and capital lease obligations

    2,332  

Accumulated Deficit

    (50,818 )

Stockholders' equity

    63,627  

Comparative Historical and Unaudited Pro Forma Per Share Data

        The information below reflects the historical net loss and book value per share of Synta common stock and the historical net loss and book value per share of Madrigal common stock in comparison

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with the unaudited pro forma net loss and book value per share after giving effect to the merger of Synta with Madrigal. The unaudited pro forma net loss and book value per share does not give effect to the proposed reverse stock split of Synta common stock described in Proposal No. 2.

        You should read the tables below in conjunction with the audited and unaudited financial statements of Synta incorporated by reference in this proxy statement and the audited and unaudited financial statements of Madrigal included elsewhere in this proxy statement and the related notes and the unaudited pro forma condensed combined financial information and notes related to such financial statements included elsewhere in this proxy statement.


SYNTA

 
  Three Months
Ended
March 31,
2016
  Year Ended
December 31,
2015
 

Historical Per Common Share Data:

             

Basic and diluted net loss per share

  $ (0.05 ) $ (0.53 )

Book value per share

    0.32     0.37  


MADRIGAL

 
  Three Months
Ended
March 31,
2016
  Year Ended
December 31,
2015
 

Historical Per Common Share Data:

             

Basic and diluted net loss per share

  $ (1.55 ) $ (6.38 )

Book value per share

    (45.78 )   (44.23 )


SYNTA AND MADRIGAL

 
  Three Months
Ended
March 31,
2016
  Year Ended
December 31,
2015
 

Historical Per Common Share Data:

             

Basic and diluted net loss per share

  $ (0.02 ) $ (0.19 )

Book value per share

    0.16      

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MARKET PRICE AND DIVIDEND INFORMATION

        Synta common stock is listed on The NASDAQ Global Market under the symbol "SNTA" The following table presents, for the periods indicated, the range of high and low per share sales prices for Synta common stock as reported on The NASDAQ Global Market for each of the periods set forth below. Madrigal is a private company and its common stock is not publicly traded. These per share sales prices do not give effect to the proposed reverse stock split of Synta common stock to be implemented prior to the closing of the merger.


Synta Common Stock

 
  High   Low  

Year Ended December 31, 2014

             

First Quarter

  $ 7.22   $ 4.07  

Second Quarter

  $ 4.60   $ 3.91  

Third Quarter

  $ 4.97   $ 2.94  

Fourth Quarter

  $ 3.44   $ 2.54  

Year Ended December 31, 2015

             

First Quarter

  $ 2.98   $ 1.85  

Second Quarter

  $ 3.17   $ 1.91  

Third Quarter

  $ 2.37   $ 1.57  

Fourth Quarter

  $ 2.08   $ 0.29  

Year Ended December 31, 2016

             

First Quarter

  $ 0.36   $ 0.15  

Second Quarter (until May 18, 2016)

  $ 0.45   $ 0.23  

        The closing price of Synta common stock on April 13, 2016, the last trading day prior to the public announcement of the merger, was $0.24 per share and the closing price of Synta common stock on April 14, 2016 was $0.41 per share, in each case as reported on The NASDAQ Global Market.

        Because the market price of Synta common stock is subject to fluctuation, the market value of the shares of Synta common stock that Madrigal stockholders will be entitled to receive in the merger may increase or decrease.

        Assuming successful application for initial listing with The NASDAQ Global Market or The NASDAQ Capital Market, following the completion of the merger, Synta common stock will be listed on The NASDAQ Global Market or The NASDAQ Capital Market and will trade under Synta's new name, "Madrigal Pharmaceuticals, Inc.," and new trading symbol "MDGL."

        As of [·], 2016, the record date for the Annual Meeting, Synta had approximately [·] holders of record of its common stock. As of May 18, 2016, Madrigal had three holders of record of its common stock.

Dividends

        Synta has never paid or declared any cash dividends on its common stock and Synta is currently prohibited from making any dividend payment under the terms of its Loan and Security Agreement with General Electric Capital Corporation, or GECC, and under the terms of the Merger Agreement. Synta currently intends to retain all available funds and any future earnings to fund the development and expansion of its business, and Synta does not anticipate paying any cash dividends in the foreseeable future. Any future determination to pay dividends will be at the discretion of Synta's board of directors and will depend on Synta's financial condition, results of operations, contractual restrictions, capital requirements, and other factors that Synta's board of directors deems relevant.

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        Madrigal has never paid or declared any cash dividends on its common stock. If the merger does not occur, Madrigal does not anticipate paying any cash dividends on its common stock in the foreseeable future, and Madrigal intends to retain all available funds and any future earnings to fund the development and expansion of its business. Any future determination to pay dividends will be at the discretion of Madrigal's board of directors and will depended upon a number of factors, including its results of operations, financial condition, prospects, contractual restrictions, restrictions imposed by applicable law and other factors Madrigal's then-current board of directors deems relevant.

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RISK FACTORS

        The combined company will be faced with a market environment that cannot be predicted and that involves significant risks, many of which will be beyond its control. In addition to the other information contained in this proxy statement, you should carefully consider the material risks described below before deciding how to vote your shares of Synta common stock. In addition, you should read and consider the risks associated with the business of Synta because these risks may also affect the combined company—these risks can be found in Synta's 10-K, as updated by Synta's 10-Q, both of which are filed with the SEC. You should also read and consider the other information in this proxy statement and the other documents incorporated by reference into this proxy statement. Please see the section entitled "Where You Can Find More Information" on page 246 in this proxy statement.

Risks Related to the Merger

The number of shares that Madrigal securityholders will receive is not adjustable based on the market price of Synta common stock, so the merger consideration at the closing may have a greater or lesser value than the market price at the time the Merger Agreement was signed.

        The Merger Agreement has set the exchange ratio formula for Madrigal common stock, subject to adjustment based on the proposed reverse stock split to be implemented prior to the closing of the merger. Any changes in the market price of Synta common stock before the completion of the merger will not affect the number of shares Madrigal securityholders will be entitled to receive pursuant to the Merger Agreement. Therefore, if before the completion of the merger the market price of Synta common stock declines from the market price on the date of the Merger Agreement, then Madrigal securityholders could receive merger consideration with substantially lower value. Similarly, if before the completion of the merger, the market price of Synta common stock increases from the market price on the date of the Merger Agreement, then Madrigal securityholders could receive merger consideration with substantially more value for their shares of Madrigal capital stock than the parties had negotiated for in the establishment of the exchange ratio. The Merger Agreement does not include a price-based termination right.

The announcement and pendency of the merger could have an adverse effect on Synta's business, financial condition, results of operations, or business prospects.

        While there have been no significant adverse effects to date, the announcement and pendency of the merger could disrupt Synta's businesses in the following ways, among others:

        Should they occur, any of these matters could adversely affect Synta's financial condition, results of operations, or business prospects.

The market price of Synta's common stock following the merger may decline as a result of the transaction.

        The market price of Synta's common stock may decline as a result of the merger for a number of reasons, including if:

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Even if the merger is consummated, Synta and Madrigal may fail to realize the anticipated benefits of the merger.

        The success of the merger will depend on, among other things, the combined company's ability to achieve its business objectives, including the successful development of its product candidates. If the combined company is not able to achieve these objectives, the anticipated benefits of the merger may not be realized fully, may take longer to realize than expected, or may not be realized at all.

        Synta and Madrigal have operated and, until the completion of the merger, will continue to operate independently. Following the completion of the merger, it is possible that the integration process could result in the loss of key employees, the disruption of each company's ongoing business, an adverse impact on the value of its assets, or inconsistencies in standards, controls, procedures or policies that could adversely affect Synta's ability to comply with reporting obligations as a public company, to satisfy its obligations to third parties or to achieve the anticipated benefits of the merger. Integration efforts between the two companies will also divert management's attention and resources. Any delays in the integration process or inability to realize the full extent of the anticipated benefits of the merger could have an adverse effect on Synta's business and the results of its operations. Such an adverse effect on the business may affect the value of the shares of the combined company's common stock after the completion of the merger.

        Potential difficulties that may be encountered in the integration process include the following:

        In addition, Madrigal could be materially adversely affected prior to the closing of the merger, which could have a material adverse effect on the combined company if Synta is required to complete the merger. For example, Synta is required under the Merger Agreement to complete the merger despite any changes in general economic or political conditions or the securities market in general, to the extent they do not disproportionately affect Madrigal; any changes in or affecting the industries in which Madrigal operates, to the extent they do not disproportionately affect Madrigal in any material respect; any changes, effects or circumstances resulting from the announcement or pendency of the Merger Agreement or the completion of the contemplated transactions or compliance with the terms of the Merger Agreement; and continued losses from operations or decreases in cash balances of Madrigal. If any such adverse changes occur and the merger is still completed, the combined company's stock price may suffer. This in turn may reduce the value of the merger to Synta's stockholders.

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Some Synta executive officers and directors have interests in the merger that are different from, or in addition to, yours and that may influence them to support or approve the issuance of shares of Synta common stock in connection with the merger and the related matters to be acted upon by Synta's stockholders at the Annual Meeting.

        Certain executive officers and directors of Synta participate in arrangements that provide them with interests in the merger that are different from, or in addition to, yours, including, among others, affiliate ownership of equity in Madrigal, the continued service as an executive officer or director of the combined company, severance benefits, the acceleration of stock options restricted stock and restricted stock unit vesting and continued indemnification.

        For example, Synta has entered into certain employment and severance benefits agreements with each of its named executive officers that may result in the receipt by such named executive officers of cash severance payments and other benefits with a total value of approximately $3.2 million (collectively, not individually, and including the value of the accelerated vesting of unvested restricted stock awards and the vesting of restricted stock units awards), based on data available as of May 2, 2016, the latest practicable date prior to the filing of this proxy statement, and assuming a covered termination of employment of each named executive officer's employment as of such date. The closing of the merger will also result in the vesting of 3,300,000 restricted stock unit awards, whether or not there is a covered termination of such named executive officer's employment. The value of these awards is included in the total value of cash severance payments and other benefits described above.

        By way of further example, at the effective time of the merger, the officers of the combined company will include Paul A. Friedman, M.D., former director of Synta, who will be the Chief Executive Officer and Chairman of the combined company, and Rebecca Taub, M.D., a current executive officer of Madrigal who will be the Chief Medical Officer, Executive Vice President, Research & Development and Director, of the combined company. Dr. Friedman is the spouse of Dr. Taub. Dr. Friedman and Dr. Taub will have significant beneficial ownership interests in the combined company due in part to the post-closing entity's equity compensation arrangements with Dr. Friedman and Dr. Taub. Assuming the full vesting and exercise of options to purchase 14,875,669 shares of common stock and the vesting 5,950,267 shares of restricted stock, and based on the projected number of shares of Synta common stock to be outstanding immediately after the closing, Dr. Friedman and Dr. Taub would have a pro forma stock ownership of 60,493,023 shares of the combined company, or approximately 14.5% immediately after the closing of the merger. Additionally, Marc R. Schneebaum is currently the Chief Financial Officer of Synta and will continue as the Chief Financial Officer of the combined company after the effective time of the merger and Keith R. Gollust is currently a director of Synta and will continue as a director of the combined company after the effective time of the merger. As further discussed under the heading "Background of the Merger," Dr. Friedman was excluded from certain discussions of Synta's board of directors involving its consideration of the potential merger with Madrigal and was excluded at the time Synta's board of directors voted in favor of the transaction contemplated by the Merger Agreement.

        These interests, among others, may have influenced or may influence the officers and directors of Synta to support or approve the issuance of shares of Synta common stock in connection with the merger and the related matters to be acted upon by Synta's stockholders at the Annual Meeting. For more information concerning the interests of Synta executive officers and directors, see the section entitled "The Merger—Interests of the Synta Directors and Executive Officers in the Merger" in this proxy statement.

Synta's stockholders will have a reduced ownership and voting interest in, and will exercise less influence over the management of, the combined company following the completion of the merger.

        After the completion of the merger, the current stockholders of Synta will own a significantly smaller percentage of the combined company than their ownership of Synta prior to the merger. At the

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effective time of the merger, Synta's equityholders will collectively own approximately 36% of the outstanding shares of the combined company, assuming no future, unanticipated issuances of Synta or Madrigal capital stock prior to closing of the merger. This calculation does not contemplate outstanding Synta option awards, which will remain outstanding under their existing terms following the merger, nor does it include equity awards in the amount of 20,825,936 shares of common stock of the combined company that are expected to be granted immediately after the completion of the merger to Paul A. Friedman, M.D., and Rebecca Taub, M.D., as executive officers of the combined company. In addition, the seven-member board of directors of the combined company will initially be comprised of five Madrigal directors, one current Synta director and one additional director mutually agreed to by Synta and Madrigal. Consequently, Synta's stockholders will be able to exercise less influence over the management and policies of the combined company than they currently exercise over the management and policies of Synta.

Synta's stockholders may not realize a benefit from the merger commensurate with the ownership dilution they will experience in connection with the merger.

        If the combined company is unable to realize the full strategic and financial benefits anticipated from the merger, Synta's stockholders will have experienced substantial dilution of their ownership interests without receiving any commensurate benefit, or only receiving part of the commensurate benefit to the extent the combined company is able to realize only part of the strategic and financial benefits currently anticipated from the merger.

Failure to complete the merger may adversely affect Synta's common stock price and future business and operations.

        If the merger is not completed, Synta is subject to the following risks:

        In addition, if the Merger Agreement is terminated and Synta's board of directors determines to seek another business combination, there can be no assurance that Synta will be able to find a transaction that is superior or equal in value to the merger.

The conditions under the Merger Agreement to Madrigal's consummation of the merger may not be satisfied at all or in the anticipated timeframe.

        The obligation of Madrigal to complete the merger is subject to certain conditions, including the approval by Synta's stockholders of certain matters and other customary closing conditions, including, among other things, the accuracy of the representations and warranties contained in the Merger Agreement, subject to certain materiality qualifications, compliance by the parties with their respective covenants under the Merger Agreement and no law or order preventing the merger and related transactions. Synta also intends to pursue all required approvals in accordance with the Merger Agreement. However, no assurance can be given that the required approvals will be obtained and, even

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if all such approvals are obtained, no assurance can be given as to the terms, conditions and timing of the approvals or that they will satisfy the terms of the Merger Agreement.

During the pendency of the merger, Synta may not be able to enter into a business combination with another party at a favorable price because of restrictions in the Merger Agreement, which could adversely affect their businesses.

        Covenants in the Merger Agreement generally prohibit Synta and Madrigal from entering into certain extraordinary transactions with any third party, including mergers, purchases or sales of assets, or other business combinations, subject to certain exceptions relating to fiduciary duties, or from completing other transactions that are not in the ordinary course of business pending completion of the merger, including transactions that may be favorable to the companies or their stockholders. As a result, if the merger is not completed, Synta's stockholders may be adversely affected by its inability to pursue other beneficial opportunities during the pendency of the merger.

Provisions of the Merger Agreement may discourage third parties from submitting alternative acquisition proposals, including proposals that may be superior to the merger.

        The terms of the Merger Agreement prohibit Synta from soliciting alternative takeover proposals or cooperating with persons making unsolicited takeover proposals, except in limited circumstances when its board of directors determines in good faith, after consultation with its outside legal counsel and financial advisors, that an unsolicited bona fide written competing proposal constitutes, or would reasonably be expected to lead to, a superior competing proposal, and that failure to pursue such proposal would be considered a breach of the board's fiduciary duties. If Synta terminates the Merger Agreement because it enters into an alternative superior transaction, Synta would be required to pay a termination fee of $1.25 million to Madrigal. Such termination fee may discourage third parties from submitting competing takeover proposals to Synta, and may cause the board of directors to be less inclined to recommend a competing proposal.

The lack of a public market for Madrigal shares makes it difficult to determine the fair market value of Madrigal, and the merger consideration to be issued to Madrigal securityholders may exceed the actual value of Madrigal.

        The outstanding capital stock of Madrigal is privately held and is not traded on any public market, which makes it difficult to determine the fair market value of Madrigal. There can be no assurances that the merger consideration to be issued to Madrigal securityholders will not exceed the actual value of Madrigal.

Synta and the combined company will incur substantial transaction-related costs in connection with the merger.

        Synta has incurred, and expects to continue to incur, a number of non-recurring transaction-related costs associated with completing the merger and combining the two companies. These fees and costs have been, and will continue to be, substantial. Non-recurring transaction costs include, but are not limited to, fees paid to legal, financial and accounting advisors, severance and benefit costs, filing fees and printing costs. Additional unanticipated costs may be incurred in the integration of Synta's business with Madrigal's business, which may be higher than expected and could have a material adverse effect on the combined company's financial condition and operating results.

A failure by the combined company upon the completion of the merger to comply with the initial listing standards of The NASDAQ Global Market or The NASDAQ Capital Market may subject its stock to delisting from The NASDAQ Stock Market.

        Upon completion of the merger, Synta will be required to meet the initial listing requirements to maintain the listing and continued trading of its shares on The NASDAQ Global Market or The

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NASDAQ Capital Market. These initial listing requirements are more difficult to achieve than the continued listing requirements under which Synta is now trading. Based on information currently available to Synta, Synta anticipates that its stock will be unable to meet the $4.00 minimum bid price initial listing requirement at the closing of the merger unless it effects a reverse stock split. If Synta is unable to satisfy these requirements, The NASDAQ Stock Market may notify Synta that its stock will be subject to delisting from The NASDAQ Global Market. Pursuant to the Merger Agreement, Synta agreed to use its commercially reasonable efforts to cause the shares of Synta common stock being issued in the merger to be approved for listing on The NASDAQ Global Market (or such other NASDAQ market which Synta's common stock then trades) at or prior to the effective time of the merger. Madrigal agreed to use its commercially reasonable efforts to provide the information required for an initial listing application pursuant to NASDAQ Stock Market Rule 5110 and to fully cooperate and participate in preparing such application and obtaining such listing. In addition, often times a reverse stock split will not result in a trading price for the affected common stock that is proportional to the ratio of the split. Synta believes that the proposed reverse stock split will be in the best interest of the combined company and its stockholders. However, Synta cannot assure you that the implementation of the reverse stock split will have a positive impact on the price of its common stock.

The shares of Synta common stock issuable in the merger constitute restricted securities under federal securities laws and are subject to additional restrictions on transfer. As a result, the shares will not be freely tradable following the merger, and stockholders receiving them may never be able to achieve liquidity.

        The shares of Synta common stock issued as consideration in the merger will not immediately be registered under the Securities Act. The shares of Synta common stock will constitute "restricted stock" under the Securities Act and, therefore, such shares may not be sold unless the shares are registered or unless an exemption from the registration and prospectus delivery requirements of the Securities Act is available. As a general matter, holders of such shares will not be able to transfer any of their shares until at least six months after receiving shares of Synta common stock, which is when the shares would first be eligible to be sold under Rule 144 promulgated under the Securities Act, assuming the conditions thereof are otherwise satisfied.

        Pursuant to the Merger Agreement, within 60 days of the closing date of the merger, Synta is obligated to file with the SEC a registration statement on Form S-3 (or if Form S-3 is not available, such other form as may provide for a resale of the shares of Synta common stock issued pursuant to the merger), covering the resale of the shares of Synta common stock received in exchange for shares of Madrigal capital stock pursuant to the merger. Synta is also obligated to use commercially reasonable efforts to cause such registration statement to be declared effective as soon as possible following the filing of the registration statement and remain effective.

        Stockholders receiving such Synta shares in the merger will not be able to achieve liquidity with respect to their shares of Synta common stock until the time that a registration statement covering the resale of such shares is declared effective and, as a result, holders of such shares may be required to bear the financial risks of this investment until that time.

The success of the proposed business combination of Synta and Madrigal will depend in part on relationships with third parties, which relationships may be affected by third-party preferences or public attitudes about the merger. Any adverse changes in these relationships could adversely affect Synta's or Madrigal's business, financial condition, or results of operations.

        The success of the merger will be in part dependent on the combined entity's ability to maintain and renew the business relationships of both Synta and Madrigal and to establish new business relationships. There can be no assurance that the management of either Synta or Madrigal will be able to maintain such business relationships, or enter into or maintain new business contracts and other business relationships, on acceptable terms, if at all. The failure to maintain important business

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relationships could have a material adverse effect on the business, financial condition, or results of operations of Synta and Madrigal.

Synta or the combined company may become involved in securities class action litigation that could divert management's attention and harm the combined company's business, and insurance coverage may not be sufficient to cover all costs and damages.

        In the past, securities class action or shareholder derivative litigation often follows certain significant business transactions, such as the sale of a business division or announcement of a merger. The combined company may become involved in this type of litigation in the future. Litigation often is expensive and diverts management's attention and resources, which could adversely affect the combined company's business.

Risks Related to the Proposed Reverse Stock Split

The reverse stock split may not increase the combined company's stock price over the long-term.

        The principal purpose of the reverse stock split is to increase the per-share market price of Synta's common stock. It cannot be assured, however, that the reverse stock split will accomplish this objective for any meaningful period of time. While it is expected that the reduction in the number of outstanding shares of common stock will proportionally increase the market price of Synta's common stock, it cannot be assured that the reverse stock split will increase the market price of its common stock by a multiple of the proposed reverse stock split ratio, or result in any permanent or sustained increase in the market price of Synta's common stock, which is dependent upon many factors, including the combined company's business and financial performance, general market conditions, and prospects for future success. Thus, while the stock price of the combined company might meet the continued listing requirements for The NASDAQ Global Market or The NASDAQ Capital Market initially, it cannot be assured that it will continue to do so.

The reverse stock split may decrease the liquidity of the combined company's common stock.

        Although the Synta board of directors believes that the anticipated increase in the market price of the combined company's common stock could encourage interest in its common stock and possibly promote greater liquidity for its stockholders, such liquidity could also be adversely affected by the reduced number of shares outstanding after the reverse stock split. The reduction in the number of outstanding shares may lead to reduced trading and a smaller number of market makers for Synta's common stock.

The reverse stock split may lead to a decrease in the combined company's overall market capitalization.

        Should the market price of the combined company's common stock decline after the reverse stock split, the percentage decline may be greater, due to the smaller number of shares outstanding, than it would have been prior to the reverse stock split. A reverse stock split may be viewed negatively by the market and, consequently, can lead to a decrease in the combined company's overall market capitalization. If the per share market price does not increase in proportion to the reverse stock split ratio, then the value of the combined company, as measured by its stock capitalization, will be reduced. In some cases, the per-share stock price of companies that have effected reverse stock splits subsequently declined back to pre-reverse split levels, and accordingly, it cannot be assured that the total market value of Synta's common stock will remain the same after the reverse stock split is effected, or that the reverse stock split will not have an adverse effect on Synta's stock price due to the reduced number of shares outstanding after the reverse stock split.

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Risks Related to Synta

Synta may not be able to complete the merger and may elect to pursue another strategic transaction similar to the merger, which may not occur on commercially reasonably terms or at all.

        Synta cannot assure you that it will complete the merger in a timely manner or at all. The Merger Agreement is subject to many closing conditions and termination rights. Synta's assets currently consist primarily of cash, cash equivalents and marketable securities, and its listing on The NASDAQ Global Market. If Synta does not complete the merger, its board of directors may elect to attempt to complete another strategic transaction similar to the merger. Such attempts will likely be costly and time consuming, and Synta cannot make any assurances that a future strategic transaction will occur on commercially reasonable terms or at all.

If the merger is not completed, Synta may elect to liquidate its remaining assets, and there can be no assurances as to the amount of cash available to distribute to stockholders after paying its debts and other obligations.

        If Synta does not complete the merger, the board of directors may elect to take the steps necessary to liquidate all of its remaining assets. The process of liquidation may be lengthy and Synta cannot make any assurances regarding the timing of completing such a process. In addition, Synta would be required to pay all of its debts and contractual obligations, and to set aside certain reserves for potential future claims. There can be no assurance as to the amount of cash that will be available to distribute to stockholders after paying Synta's debts and other obligations and setting aside funds for reserves, nor as to the timing of any such distribution.

Synta has a substantial accumulated deficit and expects to continue to incur losses for future periods.

        As of March 31, 2016, Synta had an accumulated deficit of $712.8 million. Synta had a net loss of $6.5 million for the quarter ended March 31, 2016, and net losses of $68.7 million and $86.2 million for the years ended December 31, 2015 and December 31, 2014, respectively. Synta's losses for other periods have historically resulted principally from costs incurred in connection with Synta's research and development activities, including clinical trials, and from general and administrative expenses associated with its operations. Synta expects to continue to incur losses for future periods, including periods following completion of the merger. As a result, following the completion of the merger, the combined company will need to generate significant revenues to achieve profitability in the future or, if it does achieve profitability for any particular period, to sustain or grow its profitability on a quarterly or annual basis. Synta derived a substantial portion of its revenue in past years from its strategic alliances and collaborations, which have all terminated. Synta does not currently have any source of product revenue.

Risks Related to Synta's Common Stock

The market price of Synta's common stock has historically been highly volatile and the merger may result in significant stock price and trading volume fluctuations.

        The trading price of Synta's common stock has historically been highly volatile, and the merger may result in significant stock price and trading volume fluctuations. Synta cannot predict precisely the impact the announcement, pendency or completion of the merger will have on its stock price. Additionally, the stock market in general has experienced extreme price and volume fluctuations. The market prices of securities of pharmaceutical, biopharmaceutical and biotechnology companies in particular have been extremely volatile and have experienced fluctuations that have often been unrelated or disproportionate to operating performance.

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If Synta fails to continue to meet all applicable NASDAQ Global Market requirements and The NASDAQ Stock Market determines to delist its common stock, the delisting could adversely affect the market liquidity of Synta's common stock, impair the value of your investment, harm Synta's business, and impair its ability to complete the merger.

        Synta's common stock is currently listed on The NASDAQ Global Market. In order to maintain that listing, Synta must satisfy minimum financial and other requirements. On December 3, 2015, Synta received notice from the Listing Qualifications Department of The NASDAQ Stock Market that its common stock had not met the $1.00 per share minimum bid price requirement for the last 30 consecutive business days pursuant to NASDAQ Stock Market Listing Rule 5450(a)(1) and that, if Synta were unable to demonstrate compliance with this requirement during the applicable grace periods, its common stock would be delisted after that time. The notification letter stated that pursuant to NASDAQ Stock Market Listing Rule 5810(c)(3)(A) Synta would be afforded 180 calendar days, or until May 31, 2016, to regain compliance with the minimum bid price requirement. In order to regain compliance, shares of Synta's common stock must maintain a minimum closing bid price of at least $1.00 per share for a minimum of ten consecutive business days. If Synta does not regain compliance by May 31, 2016, NASDAQ Stock Market will provide written notification to it that its common stock will be delisted. At that time, Synta may appeal NASDAQ Stock Market's delisting determination to a NASDAQ Stock Market Listing Qualifications Panel. Alternatively, Synta may be eligible for an additional 180 day grace period if it satisfies all of the requirements, other than the minimum bid price requirement, for listing on The NASDAQ Capital Market set forth in NASDAQ Stock Market Listing Rule 5505. The closing bid price of Synta's common stock on The NASDAQ Global Market was $0.3605 on May 18, 2016.

        While Synta intends to engage in efforts to regain compliance, including by effecting the proposed reverse stock split, and thus maintain its listing, there can be no assurance that it will be able to regain compliance during the applicable time periods set forth above. If Synta fails to continue to meet all applicable NASDAQ Global Market requirements in the future and The NASDAQ Stock Market determines to delist its common stock, the delisting could substantially decrease trading in Synta's common stock and adversely affect the market liquidity of Synta's common stock; adversely affect Synta's ability to obtain financing on acceptable terms, if at all, for the continuation of its operations; and harm Synta's business. Additionally, the market price of Synta's common stock may decline further and stockholders may lose some or all of their investment.

A small number of Synta's stockholders beneficially own a substantial amount of Synta's common stock and have substantial control over Synta; therefore, your ability to influence corporate matters may be limited.

        Certain stockholders affiliated with Synta's officers and directors collectively beneficially own or control approximately 18.8% of Synta's outstanding common stock as of May 2, 2016 and acting together, may have the ability to affect matters submitted to Synta's stockholders for approval, including the approval of significant transactions, like the merger. This concentration of ownership may have the effect of delaying, deferring or preventing a strategic transaction, even if such a transaction would benefit other stockholders.

Fluctuations in Synta's operating results could adversely affect the price of Synta's common stock.

        Synta's operating results are likely to fluctuate significantly from quarter to quarter and year to year. These fluctuations could cause Synta's stock price to decline. Some of the factors that may cause Synta's operating results to fluctuate on a period-to-period basis include:

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        Due to fluctuations in Synta's operating results, a period-to-period comparison of Synta's results of operations may not be meaningful, and investors should not rely on them as a good indication of Synta's future performance. Fluctuations in Synta's operating results may not meet the expectations of securities analysts or investors. Failure to meet these expectations may cause the price of Synta's common stock to decline.

        These and other external factors may cause the market price and demand for Synta's common stock to fluctuate substantially, which may limit or prevent investors from readily selling its shares of common stock and may otherwise negatively affect the liquidity of Synta's common stock. In addition, in the past, when the market price of a stock has been volatile, holders of that stock have instituted securities class action litigation against the company that issued the stock. If any of Synta's stockholders brought a lawsuit against Synta, it could incur substantial costs defending the lawsuit. Such a lawsuit could also divert the time and attention of Synta's management.

If Synta's stockholders sell a substantial number of shares of Synta's common stock in the public market, Synta's stock price may decline.

        Synta's current trading volumes are modest, and sales of a substantial number of shares of its common stock in the public market, or the perception that these sales could occur, could cause the market price to decline. Such sales also might make it more difficult for Synta to sell equity securities in the future at a time and at a price that it deems appropriate. If there are more shares of Synta's common stock offered for sale than buyers are willing to purchase, the market price of Synta's common stock may decline to a market price at which buyers are willing to purchase the offered shares and sellers remain willing to sell the shares. The number of shares of Synta's common stock owned by its stockholders and available for sale in the public market is limited only to the extent provided under applicable federal securities laws. In addition, Synta may, in the future, issue additional shares of its common stock as compensation to its employees, directors or consultants, in connection with strategic alliances, collaborations, acquisitions or other transactions or to raise capital. Accordingly, sales of a substantial number of shares of Synta's common stock in the public market could occur at any time.

Provisions of Synta's charter, bylaws, and Delaware law may make an acquisition of Synta or a change in its management more difficult.

        Certain provisions of Synta's restated certificate of incorporation and restated bylaws could discourage, delay, or prevent a merger, acquisition, or other change in control that stockholders may consider favorable, including transactions in which stockholders might otherwise receive a premium for their shares. These provisions also could limit the price that investors might be willing to pay in the future for shares of Synta's common stock, thereby depressing the market price of its common stock. Stockholders who wish to participate in these transactions may not have the opportunity to do so. Furthermore, these provisions could prevent or frustrate attempts by Synta's stockholders to replace or remove Synta's management.

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        These provisions:

        In addition, because Synta is incorporated in Delaware, it is governed by the provisions of Section 203 of the Delaware General Corporation Law, or DGCL, which may, unless certain criteria are met, prohibit large stockholders, in particular those owning 15% or more of Synta's outstanding voting stock, from merging or combining with Synta for a prescribed period of time.

Synta does not anticipate paying cash dividends, and accordingly, Synta's stockholders must rely on stock appreciation for any return on their investment.

        Synta currently intends to retain its future earnings, if any, to fund the development and growth of its business. In addition, Synta is currently prohibited from making a dividend payment under the terms of its loan and security agreement with GECC and under the terms of the Merger Agreement. As a result, capital appreciation, if any, of Synta's common stock will be the sole source of gain on an investment in Synta's common stock for the foreseeable future.

Risks Related to Madrigal's Business

Madrigal has a limited operating history, has incurred significant operating losses since inception and expects to incur significant operating losses for the foreseeable future. Madrigal may never become profitable or, if achieved, be able to sustain profitability.

        To date, Madrigal has funded its operations primarily through private placement offerings of debt and equity securities. From September 16, 2011 through March 31, 2016, Madrigal received net proceeds of approximately $15.5 million from the issuance of convertible notes. In addition, on April 13, 2016, concurrent with the execution of the Merger Agreement, certain securityholders of Madrigal agreed to invest $9.0 million of gross proceeds in Madrigal prior to the consummation of the merger, which is referred to herein as the Private Placement. As of March 31, 2016, Madrigal had cash and cash equivalents of $0.6 million. Madrigal has incurred significant operating losses since its inception and expects to incur significant losses for the foreseeable future as Madrigal continues its clinical trial and development programs for MGL-3196 and other future product candidates. In the future, Madrigal intends to continue to conduct research and development, clinical testing, regulatory compliance and, if MGL-3196 or other future product candidates are approved, sales and marketing

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activities that, together with anticipated general and administrative expenses, will likely result in Madrigal incurring further significant losses for the foreseeable future.

        Madrigal currently generates no revenue from product sales, and may never be able to commercialize MGL-3196 or other future product candidates. Madrigal does not currently have the required approvals to market MGL-3196 or any other future product candidates, and Madrigal may never receive them. Madrigal may not be profitable even if it or any of its future development partners succeed in commercializing any of Madrigal's product candidates. Because of the numerous risks and uncertainties associated with developing and commercializing Madrigal's product candidates, Madrigal is unable to predict the extent of any future losses or when it will become profitable, if at all.

Madrigal's business depends on the success of MGL-3196, which is still in clinical development. If Madrigal is unable to obtain regulatory approval for or successfully commercialize MGL-3196, its business will be materially harmed.

        To date, the sole focus of Madrigal's product development has been MGL-3196, a liver-directed selective thyroid hormone receptor beta agonist for potential use in NASH and FH. Successful continued development and ultimate regulatory approval of MGL-3196 for NASH or genetic dyslipidemias, such as FH, is critical to the future success of its business. Madrigal has invested, and will continue to invest, a significant portion of its time and financial resources in the clinical development of MGL-3196. Madrigal will need to raise sufficient funds to successfully complete its clinical development program for MGL-3196 in NASH and FH. The future regulatory and commercial success of MGL-3196 is subject to a number of risks, including the following:

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        Of the large number of drugs in development in the pharmaceutical industry, only a small percentage results in the submission of a new drug application, or NDA, to the FDA and even fewer are approved for commercialization. Furthermore, even if Madrigal does receive regulatory approval to market MGL-3196, any such approval may be subject to limitations on the indicated uses or patient populations for which Madrigal may market the products. Accordingly, even if Madrigal is able to obtain the requisite financing to continue to fund its development programs, Madrigal may be unable to successfully develop or commercialize MGL-3196. If Madrigal or any of its future development partners are unable to develop, or obtain regulatory approval for, or, if approved, successfully commercialize MGL-3196, Madrigal may not be able to generate sufficient revenue to continue its business.

The results of preclinical studies and early clinical trials are not always predictive of future results. Any product candidate that Madrigal advances into clinical trials, including MGL-3196, may not have favorable results in later clinical trials or receive regulatory approval.

        Drug development has inherent risk. Madrigal will be required to demonstrate through adequate and well-controlled clinical trials that its product candidates are safe and effective, with a favorable benefit-risk profile, for use in their target indications before Madrigal can seek regulatory approvals for their commercial sale. Clinical studies are expensive, difficult to design and implement, can take many years to complete and are uncertain as to outcome. Delay or failure can occur at any stage of development, including after commencement of any of Madrigal's clinical trials. In addition, success in early clinical trials does not mean that later clinical trials will be successful, because later-stage clinical trials may be conducted in broader patient populations and involve different study designs. For instance, Madrigal's Phase 1 results may not be predictive of any future Phase 2 results. Furthermore, Madrigal's future trials will need to demonstrate sufficient safety and efficacy in larger patient populations for approval by regulatory authorities. Companies frequently suffer significant setbacks in advanced clinical trials, even after earlier clinical trials have shown promising results. In addition, only a small percentage of drugs under development result in the submission of an NDA to the FDA and even fewer are approved for commercialization.

        Madrigal cannot be certain that any of its ongoing or future clinical trials will be successful, and any safety concerns observed in any one of its clinical trials in its targeted indications could limit the prospects for regulatory approval of its product candidates in those and other indications.

If Madrigal encounters difficulties enrolling patients in its clinical trials, its clinical development activities could be delayed or otherwise adversely affected.

        Madrigal may not be able to initiate, continue, or complete clinical trials required by the FDA or foreign regulatory agencies for MGL-3196 if it is unable to locate and enroll a sufficient number of eligible patients to participate in these clinical trials. Patient enrollment, a significant factor in the timing to conduct and complete clinical trials, is affected by many factors, including the size and nature of the patient population, the proximity of patients to clinical sites, the eligibility criteria for the trial, the design of the clinical trial, competing clinical trials, and clinicians' and patients' perceptions as to

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the potential advantages and disadvantages of the product candidate being studied in relation to other available therapies, including any new drugs that may be approved for the indications Madrigal is investigating. In the proposed clinical trials, patient willingness to undergo a liver biopsy in Madrigal's NASH trials, and identification of patients willing to participate in Madrigal's FH trials due to the rarity of the disease, are also risk factors. Potential patients for MGL-3196 may not be adequately diagnosed or identified with the diseases which Madrigal is targeting or may not meet the entry criteria for Madrigal's studies.

        The FDA typically requires sponsors of lipid-lowering product candidates to conduct drug-drug interaction studies with statins because statins may have increased safety risks when administered together with other drug therapies that affect their pharmacokinetic profile. Accordingly, shortly after Madrigal submitted an IND for MGL-3196, the FDA placed a partial clinical hold on MGL-3196 with respect to clinical dosing of MGL-3196 with statins. Madrigal conducted its planned clinical dose escalation trials and, later, upon submitting a request to the FDA, the FDA advised Madrigal that conducting clinical drug interaction studies between MGL-3196 and statins might be sufficient to address the partial clinical hold. Madrigal has completed one clinical drug interaction study between MGL-3196 and two statins, and is currently conducting a second similar drug interaction study between MGL-3196 and a third statin, the results of which will be submitted, along with other information, to the FDA in support of Madrigal's request to the FDA that it remove the partial clinical hold. The timing of the FDA's response may affect the timing or enrollment of clinical trials in which MGL-3196 is dosed concomitantly with statins, including the FH Phase 2 clinical trial and, to a lesser extent, the NASH Phase 2 clinical trial.

        Madrigal will be required to identify and enroll a sufficient number of patients for each of its ongoing and planned clinical trials of MGL-3196 for NASH and FH indications, respectively. Madrigal also may encounter difficulties in identifying and enrolling NASH patients and FH patients with a stage of disease appropriate for its ongoing or future clinical trials. Madrigal may not be able to initiate or continue clinical trials if it is unable to locate a sufficient number of eligible patients to participate in the clinical trials required by the FDA or other foreign regulatory agencies. In addition, the process of finding and diagnosing patients may prove costly. Madrigal's inability to enroll a sufficient number of patients for any of its clinical trials would result in significant delays or may require Madrigal to abandon one or more clinical trials.

If clinical trials or regulatory approval processes for Madrigal's product candidates are prolonged, delayed or suspended, Madrigal may be unable to commercialize its product candidates on a timely basis, which would require Madrigal to incur additional costs and delay Madrigal's receipt of any revenue from potential product sales.

        Madrigal cannot predict whether it will encounter problems with any of its completed, ongoing or planned clinical trials that will cause Madrigal or any regulatory authority to delay or suspend those clinical trials or delay the analysis of data derived from them. A number of events, including any of the following, could delay the completion of Madrigal's ongoing and planned clinical trials and negatively affect its ability to obtain regulatory approval for, and to market and sell, a particular product candidate:

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        Commercialization of Madrigal's product candidates may be delayed by the imposition of additional conditions on its clinical trials by the FDA or any other applicable foreign regulatory authority or the requirement of additional supportive studies by the FDA or such foreign regulatory authority.

        Madrigal does not know whether Madrigal's clinical trials will begin as planned, will need to be restructured, or will be completed on schedule, if at all. Delays in the initiation, enrollment or completion of Madrigal's clinical trials will result in increased development costs for its product candidates, and its financial resources may be insufficient to fund any incremental costs. In addition, if Madrigal's clinical trials are delayed, its competitors may be able to bring products to market before it does and the commercial viability of its product candidates could be limited.

If Madrigal fails to obtain the capital necessary to fund its operations, Madrigal will be unable to successfully develop and commercialize MGL-3196 and other future product candidates.

        Although Madrigal believes that the net cash of Synta available at the closing of the merger, together with Madrigal's existing cash and cash equivalents and the proceeds from the Private Placement, will be sufficient to fund Madrigal's current operations through at least the third quarter of 2017, Madrigal will require substantial additional future working capital in order to complete the remaining clinical development for MGL-3196 and Madrigal's other product candidates through potential regulatory approval and through potential commercialization of these product candidates. In particular, in order to initiate its Phase 3 clinical program for MGL-3196 in NASH, Madrigal will need to collaborate with a strategic partner or raise significant financing. Madrigal expects its spending levels to increase in connection with its clinical trials of MGL-3196 as well as other corporate activities. The amount and timing of any expenditure needed to implement Madrigal's development and commercialization programs will depend on numerous factors, including:

        Some of these factors are outside of Madrigal's control. Madrigal does not expect its existing capital resources, together with the net cash of Synta at the closing of the merger and the proceeds from the Private Placement, to be sufficient to enable it to fund the completion of its clinical trials and

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commercialization of its product candidates. Madrigal expects that it will need to raise substantial additional funds in the future.

        Madrigal has not sold any products, and it does not expect to sell or derive revenue from any product sales for the foreseeable future. Madrigal may seek additional funding through future debt financings and potentially dilutive equity financings, as well as potential additional collaborations or strategic partnerships with other companies or through non-dilutive financings. Additional funding may not be available to Madrigal on acceptable terms or at all. In addition, the terms of any financing may adversely affect the holdings or the rights of Madrigal's stockholders. In addition, the issuance of additional shares by Madrigal, or the possibility of such issuance, may cause the market price of Madrigal's shares to decline.

        If Madrigal is unable to obtain additional funding on a timely basis, Madrigal may be unable to complete planned clinical trials for MGL-3196 for NASH and FH and any of its other product candidates, and Madrigal may be required to significantly curtail some or all of its activities. Madrigal also could be required to seek funds through arrangements with collaborative partners or otherwise that may require Madrigal to relinquish rights to its product candidates or otherwise agree to terms unfavorable to Madrigal.

Madrigal's product candidates will remain subject to ongoing regulatory review even if they receive marketing approval, and if Madrigal fails to comply with continuing regulations, Madrigal could lose these approvals and the sale of any approved Madrigal commercial products could be suspended.

        Even if Madrigal receives regulatory approval to market a particular product candidate, the manufacturing, labeling, packaging, adverse event reporting, storage, advertising, promotion, and record keeping related to the product will remain subject to extensive regulatory requirements. If Madrigal fails to comply with the regulatory requirements of the FDA and other applicable domestic and foreign regulatory authorities, or previously unknown problems with any approved product, manufacturer, or manufacturing process are discovered, Madrigal could be subject to administrative or judicially imposed sanctions, including:

Madrigal's industry is highly competitive, and its product candidates may become obsolete.

        Madrigal is engaged in a rapidly evolving field. Competition from other pharmaceutical companies, biotechnology companies and research and academic institutions is intense and likely to increase. Many of those companies and institutions have substantially greater financial, technical and human resources than Madrigal. Those companies and institutions also have substantially greater experience in developing products, conducting clinical trials, obtaining regulatory approval and in manufacturing and

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marketing pharmaceutical products. Madrigal's competitors may succeed in obtaining regulatory approval for their products more rapidly than it does. Competitors have developed or are in the process of developing technologies that are, or in the future may be, the basis for competitive products. Some of these competitive products may have an entirely different approach or means of accomplishing the desired therapeutic effect than products being developed by Madrigal. Madrigal's competitors may succeed in developing products that are more effective and/or cost competitive than those it is developing, or that would render its product candidates less competitive or even obsolete. In addition, one or more of Madrigal's competitors may achieve product commercialization or patent protection earlier than Madrigal, which could materially adversely affect Madrigal's business.

If the FDA or other applicable regulatory authorities approve generic products that compete with any of Madrigal's or any of its partners' product candidates, the sales of Madrigal's product candidates would be adversely affected.

        Once an NDA or marketing authorization application outside the United States is approved, the product covered thereby becomes a "listed drug" that can, in turn, be cited by potential competitors in support of approval of an abbreviated new drug application in the United States. Agency regulations and other applicable regulations and policies provide incentives to manufacturers to create modified, non-infringing versions of a drug to facilitate the approval of an abbreviated new drug application or other application for generic substitutes in the United States and in nearly every pharmaceutical market around the world. These manufacturers might only be required to conduct a relatively inexpensive study to show that their product has the same active ingredient(s), dosage form, strength, route of administration and conditions of use, or labeling, as Madrigal's product and that the generic product is bioequivalent to Madrigal's product, meaning it is absorbed in the body at the same rate and to the same extent as Madrigal's product. These generic equivalents, which must meet the same quality standards as branded pharmaceuticals, would be significantly less costly than Madrigal's product to bring to market, and companies that produce generic equivalents are generally able to offer their products at lower prices. Thus, after the introduction of a generic competitor, a significant percentage of the sales of any branded product are typically lost to the generic product. Accordingly, competition from generic equivalents to Madrigal's product or any of its partners' future products, if any, would materially adversely affect Madrigal's future revenue, profitability and cash flows and substantially limit its ability to obtain a return on the investments Madrigal has made and expects to make in its or any of its partners' product candidates, including MGL-3196.

If physicians and patients do not accept Madrigal's future products or if the market for indications for which any product candidate is approved is smaller than expected, Madrigal may be unable to generate significant revenue, if any.

        Even if any of Madrigal's product candidates obtain regulatory approval, they may not gain market acceptance among physicians, patients, and third-party payers. Physicians may decide not to recommend its treatments for a variety of reasons including:

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        If any of Madrigal's product candidates are approved, but fail to achieve market acceptance or such market is smaller than anticipated, Madrigal may not be able to generate significant revenue and its business would suffer.

As Madrigal evolves from a company that is primarily involved in clinical development to a company that is also involved in commercialization, it may encounter difficulties in expanding its operations successfully.

        As Madrigal advances its product candidates through clinical trials, it will need to expand its development, regulatory, manufacturing, and marketing and sales capabilities and may need to further contract with third parties to provide these capabilities. As its operations expand, Madrigal likely will need to manage additional relationships with such third parties, as well as additional collaborators, distributors, marketers and suppliers.

        Maintaining third party relationships for these purposes will impose significant added responsibilities on members of its management and other personnel. Madrigal must be able to effectively manage its development efforts; recruit and train sales and marketing personnel, effectively manage its participation in the clinical trials in which its product candidates are involved and improve its managerial, development, operational and finance systems, all of which may impose a strain on Madrigal's administrative and operational infrastructure.

        If Madrigal enters into arrangements with third parties to perform sales, marketing or distribution services, any product revenues that it receives, or the profitability of these product revenues to Madrigal, are likely to be lower than if Madrigal were to market and sell any products that it develops without the involvement of these third parties. In addition, Madrigal may not be successful in entering into arrangements with third parties to sell and market its products or in doing so on terms that are favorable to Madrigal. Madrigal likely will have little control over such third parties, and any of them may fail to devote the necessary resources and attention to sell and market its products effectively. If Madrigal does not establish sales and marketing capabilities successfully, either on its own or in collaboration with third parties, Madrigal will not be successful in commercializing its products.

The uncertainty associated with pharmaceutical reimbursement and related matters may adversely affect Madrigal's business.

        Market acceptance and sales of any one or more of Madrigal's product candidates will depend on reimbursement policies and may be affected by future healthcare reform measures in the United States and in foreign jurisdictions. Government authorities and third-party payers, such as private health insurers and health maintenance organizations, decide which drugs they will cover and establish payment levels. Madrigal cannot be certain that reimbursement will be available for any of Madrigal's product candidates. Also, Madrigal cannot be certain that reimbursement policies will not reduce the demand for, or the price paid for, Madrigal products. If reimbursement is not available or is available on a limited basis, Madrigal may not be able to successfully commercialize any product candidates that it develops.

        In the United States, the Medicare Prescription Drug, Improvement, and Modernization Act of 2003, also called the Medicare Modernization Act, or MMA, changed the way Medicare covers and pays for pharmaceutical products. The legislation established Medicare Part D, which expanded Medicare coverage for outpatient prescription drug purchases by the elderly but provided authority for limiting the number of drugs that will be covered in any therapeutic class. The MMA also introduced a new reimbursement methodology based on average sales prices for physician-administered drugs.

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        The United States and several foreign jurisdictions are considering, or have already enacted, a number of legislative and regulatory proposals to change the healthcare system in ways that could affect its ability to sell its products profitably. Among policy makers and payers in the United States and elsewhere, there is significant interest in promoting changes in healthcare systems with the stated goals of containing healthcare costs, improving quality and/or expanding access to healthcare. In the United States, the pharmaceutical industry has been a particular focus of these efforts and has been significantly affected by major legislative initiatives. Madrigal expects to experience pricing pressures in connection with the sale of any products that it develops due to the trend toward managed healthcare, the increasing influence of health maintenance organizations, and additional legislative proposals.

        In March 2010, the Patient Protection and Affordable Care Act, as amended by the Health Care and Education Affordability Reconciliation Act, or collectively, ACA, became law in the United States. The goal of ACA is to reduce the cost of healthcare and substantially change the way healthcare is financed by both government and private insurers. While Madrigal cannot predict what impact on federal reimbursement policies this legislation will have in general or on Madrigal's business specifically, the ACA may result in downward pressure on pharmaceutical reimbursement, which could negatively affect market acceptance of, and the price Madrigal may charge for, any products it develops that receive regulatory approval. Madrigal also cannot predict the impact of ACA on Madrigal as many of the ACA reforms require the promulgation of detailed regulations implementing the statutory provisions, which have not yet been fully implemented.

If any product liability lawsuits are successfully brought against Madrigal or any of its collaborative partners, Madrigal may incur substantial liabilities and may be required to limit commercialization of its product candidates.

        Madrigal faces an inherent risk of product liability lawsuits related to the testing of its product candidates in seriously ill patients and will face an even greater risk if product candidates are approved by regulatory authorities and introduced commercially. Product liability claims may be brought against Madrigal or its partners by participants enrolled in Madrigal's clinical trials, patients, healthcare providers or others using, administering or selling any of Madrigal's future approved products. If Madrigal cannot successfully defend itself against any such claims, it may incur substantial liabilities. Regardless of merit or eventual outcome, liability claims may result in:

        If any of Madrigal's product candidates are approved for commercial sale, Madrigal will be highly dependent upon consumer perceptions of Madrigal and the safety and quality of its products. Madrigal could be adversely affected if it is subject to negative publicity. Madrigal could also be adversely affected if any of its products or any similar products distributed by other companies prove to be, or

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are asserted to be, harmful to patients. Also, because of Madrigal's dependence upon consumer perceptions, any adverse publicity associated with illness or other adverse effects resulting from patients' use or misuse of Madrigal's products or any similar products distributed by other companies could have a material adverse impact on Madrigal's results of operations.

        Madrigal does not currently hold product liability insurance coverage. Prior to commercialization of its product candidates, Madrigal will need to purchase insurance coverage. As a result, Madrigal may be unable to maintain or obtain sufficient insurance at a reasonable cost to protect Madrigal against losses that could have a material adverse effect on its business. These liabilities could prevent or interfere with Madrigal's product development and commercialization efforts. A successful product liability claim or series of claims brought against Madrigal, particularly if judgments exceed Madrigal's insurance coverage, could decrease Madrigal's cash resources and adversely affect its business, financial condition and results of operations.

Madrigal's employees, contractors and partners may engage in misconduct or other improper activities, including noncompliance with regulatory standards and requirements and insider trading.

        Madrigal is exposed to the risk of fraud or other misconduct by its employees, contractors or partners. Misconduct by these parties could include failures to comply with FDA regulations, to provide accurate information to the FDA, to comply with federal and state healthcare fraud and abuse laws and regulations, to report financial information or data timely, completely or accurately, or to disclose unauthorized activities to Madrigal. In particular, sales, marketing and business arrangements in the healthcare industry are subject to extensive laws and regulations intended to prevent fraud, misconduct, kickbacks, self-dealing and other abusive practices. These laws and regulations may restrict or prohibit a wide range of pricing, discounting, marketing and promotion, sales commission, customer incentive programs and other business arrangements. Third-party misconduct could also involve the improper use of information obtained in the course of clinical trials, which could result in regulatory sanctions and serious harm to Madrigal's reputation. It is not always possible to identify and deter misconduct, and the precautions Madrigal takes to detect and prevent this activity may not be effective in controlling unknown or unmanaged risks or losses or in protecting Madrigal from governmental investigations or other actions or lawsuits stemming from a failure to comply with these laws or regulations. If any such actions are instituted against Madrigal resulting from this misconduct and Madrigal is not successful in defending itself or asserting its rights, those actions could have a significant impact on its business, including the imposition of significant fines or other sanctions.

Madrigal enters into various contracts in the normal course of its business in which Madrigal indemnifies the other party to the contract. In the event Madrigal has to perform under these indemnification provisions, it could have a material adverse effect on its business, financial condition and results of operations.

        In the normal course of business, Madrigal periodically enters into academic, commercial, service, collaboration, licensing, consulting and other agreements that contain indemnification provisions. With respect to Madrigal's academic and other research agreements, Madrigal typically indemnifies the institution and related parties from losses arising from claims relating to the products, processes or services made, used, sold or performed pursuant to the agreements for which Madrigal has secured licenses, and from claims arising from Madrigal's or its potential sublicensees' exercise of rights under the agreement. With respect to Madrigal's commercial agreements, Madrigal indemnifies its vendors from any third-party product liability claims that could result from the production, use or consumption of the product, as well as for alleged infringements of any patent or other intellectual property right by a third party.

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        Should Madrigal's obligation under an indemnification provision exceed applicable insurance coverage or if Madrigal were denied insurance coverage, Madrigal's business, financial condition and results of operations could be adversely affected. Similarly, if Madrigal is relying on a collaborator to indemnify Madrigal and the collaborator is denied insurance coverage or the indemnification obligation exceeds the applicable insurance coverage, and if the collaborator does not have other assets available to indemnify Madrigal, its business, financial condition and results of operations could be adversely affected.

Because MGL-3196 has not yet received regulatory approval for any indication, it is difficult to predict the time and cost of development and Madrigal's ability to successfully complete clinical development and obtain the necessary regulatory approvals for commercialization.

        MGL-3196 has not yet received regulatory approval for the treatment of NASH, FH or any other indication, and unexpected problems may arise that could cause Madrigal to delay, suspend or terminate its development efforts in any or all indications. Further, MGL-3196 has not yet demonstrated efficacy in patients with NASH or FH, and the long-term safety consequences of a liver-directed thyroid hormone receptor beta agonist are not known. Regulatory approval of new product candidates such as MGL-3196 can be more expensive and take longer than approval for candidates for the treatment of more well-understood diseases with previously approved products.

Any product candidate in Madrigal's current or future clinical trials may cause unacceptable adverse events or have other properties that may delay or prevent its regulatory approval or commercialization or limit its commercial potential.

        Unacceptable adverse events caused by any of Madrigal's product candidates in current or future clinical trials could cause Madrigal or regulatory authorities to interrupt, delay or halt clinical trials and could result in the denial of regulatory approval by the FDA or other regulatory authorities for any or all targeted indications and markets. This in turn could prevent Madrigal from completing development of or commercializing the affected product candidate and generating revenue from its sale. If any of Madrigal's product candidates cause unacceptable adverse events in clinical trials, Madrigal may not be able to obtain regulatory approval or commercialize such product candidate.

If Madrigal fails to develop and commercialize other product candidates, Madrigal may be unable to grow its business.

        Although the development and commercialization of MGL-3196 is Madrigal's primary focus, as part of its longer-term growth strategy, Madrigal plans to evaluate the development and commercialization of other therapies related to thyroid hormone, orphan and other diseases. Madrigal will evaluate internal opportunities from its compound libraries, and also may choose to in-license or acquire other product candidates as well as commercial products to treat patients suffering from thyroid hormone, orphan or other disorders with high unmet medical needs and limited treatment options. These other product candidates may require additional, time-consuming development efforts prior to commercial sale, including preclinical studies, clinical trials and approval by the FDA and/or applicable foreign regulatory authorities. All product candidates are prone to the risks of failure that are inherent in pharmaceutical product development, including the possibility that the product candidate will not be shown to be sufficiently safe and effective for approval by regulatory authorities. In addition, Madrigal cannot assure you that any such products that are approved will be manufactured or produced economically, be successfully commercialized, be widely accepted in the marketplace, or be more effective than other commercially available alternatives.

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Risks Related to Madrigal's Intellectual Property

Madrigal's rights to develop and commercialize its product candidates are subject in part to the terms and conditions of a license to MGL-3196 granted to Madrigal by Roche.

        Madrigal entered into a research, development and commercialization agreement, or the Roche Agreement, with Hoffmann-La Roche Pharmaceutical Company Limited, or Roche, on December 18, 2008. Pursuant to the terms of the Roche Agreement, Madrigal assumed control of all development and commercialization of MGL-3196 and will own exclusive worldwide rights for all potential indications. Roche assigned all patent rights relating to MGL-3196 to Madrigal and granted Madrigal an exclusive license to use certain know-how relating to MGL-3196 in exchange for consideration consisting of an upfront payment, milestone payments tied to the achievement of product development and regulatory milestones, and royalty payments based on net sales of products containing MGL-3196, subject to certain reductions. Madrigal must use commercially reasonable efforts to conduct clinical and commercial development programs for products containing MGL-3196. If Madrigal determines that it is not reasonable to continue clinical trials or other development of MGL-3196, it may elect to cease further development and Roche may terminate the license. If Madrigal determines not to pursue the development or commercialization of MGL-3196 in certain jurisdictions, including the United States, Roche may terminate the license for such territories. The Roche Agreement will expire, unless earlier terminated pursuant to other provisions of the agreement, on the last to occur of (i) the expiration of the last valid claim of a licensed patent covering the manufacture, use or sale of products containing MGL-3196, or (ii) ten years after the first sale of a product containing MGL-3196.

        Madrigal does not have, nor has Madrigal had, any material disputes with Roche regarding the Roche Agreement. However, if there is any future dispute between Madrigal and Roche regarding the parties' rights under the Roche Agreement, Madrigal's ability to develop and commercialize MGL-3196 may be materially harmed. Any uncured, material breach under the Roche Agreement could result in Madrigal's loss of exclusive rights to MGL-3196 and may lead to a complete termination of the Roche Agreement and force Madrigal to cease product development efforts for MGL-3196.

Madrigal may fail to comply with any of its obligations under agreements pursuant to which it licenses rights or technology, which could result in the loss of rights or technology that are material to Madrigal's business.

        Madrigal may enter into license agreements from time to time. Licensing of intellectual property is important to Madrigal's business and involves complex legal, business and scientific issues. Disputes may arise regarding intellectual property subject to a licensing agreement, including but not limited to:

        If disputes over intellectual property and other rights that Madrigal has licensed or acquired from third parties prevent or impair Madrigal's ability to maintain its current licensing arrangements on acceptable terms, Madrigal may be unable to successfully develop and commercialize the affected product candidates.

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Madrigal's success depends on its ability to protect its intellectual property and its proprietary technologies.

        Madrigal's success depends on its ability to protect its intellectual property and its proprietary technologies. Madrigal's commercial success depends in part on its ability to obtain and maintain patent protection and trade secret protection for its product candidates, proprietary technologies, and their uses, as well as its ability to operate without infringing upon the proprietary rights of others.

        Madrigal can provide no assurance that its patent applications or those of its licensors will result in additional patents being issued or that issued patents will afford sufficient protection against competitors with similar technologies, nor can Madrigal provide any assurance that the patents issued will not be infringed, designed around or invalidated by third parties. Even issued patents may later be found unenforceable or may be modified or revoked in proceedings instituted by third parties before various patent offices or in courts. The degree of future protection for Madrigal's proprietary rights is uncertain. Only limited protection may be available and may not adequately protect Madrigal's rights or permit Madrigal to gain or keep any competitive advantage. This failure to properly protect the intellectual property rights relating to Madrigal's product candidates could have a material adverse effect on its financial condition and results of operations. Composition-of-matter patents on the biological or chemical active pharmaceutical ingredients are generally considered to offer the strongest protection of intellectual property and provide the broadest scope of patent protection for pharmaceutical products, as such patents provide protection without regard to any method of use or any method of manufacturing. While Madrigal owns and has licensed rights to issued composition-of-matter patents in the United States and other jurisdictions for MGL-3196, Madrigal cannot be certain that the claims in issued composition-of-matter patents will not be found invalid or unenforceable if challenged. Madrigal cannot be certain that the claims in owned and licensed patent applications covering its product candidates will be considered patentable by the United States Patent and Trademark Office, or USPTO, and valid by courts in the United States or by the patent offices and courts in foreign jurisdictions. Even if Madrigal's owned and licensed patent applications covering its product candidates do issue as patents, the patents may not be enforced against competitors. For example, a formulation patent will not be enforced against those making and marketing a product that has the same active pharmaceutical ingredient in a different formulation that is not claimed in the formulation patent. Method-of-use patents protect the use of a product for the specified method or for treatment of a particular indication. This type of patent may not be enforced against competitors making and marketing a product that has the same active pharmaceutical ingredient but is used for a method not claimed in the patent. Moreover, even if competitors do not actively promote their product for Madrigal's targeted indications, physicians may prescribe these products "off-label." Although off-label prescriptions may infringe or contribute to the infringement of method-of-use patents, the practice is common and such infringement is difficult to prevent or prosecute.

        Madrigal's licensed composition-of-matter patent from Roche for MGL-3196 is expected to expire in the United States in 2026. Madrigal's owned patents and pending patent applications that cover solid form, method of manufacturing, and use of MGL-3196 to treat various indications are expected to expire in 2033. While patent term adjustments or patent term extensions could result in later expiration dates for each of these patents, there can be no assurances that Madrigal will receive any patent adjustments or patent term extensions. The patent application process and patent maintenance and enforcement are subject to numerous risks and uncertainties, and there can be no assurance that Madrigal or any of its future development partners will be successful in protecting Madrigal's product candidates by obtaining and defending patents. These risks and uncertainties include the following:

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        In addition, Madrigal relies on the protection of its trade secrets and proprietary know-how. Although Madrigal has taken steps to protect its trade secrets and unpatented know-how, including entering into confidentiality agreements with third parties, and confidential information and inventions agreements with employees, consultants and advisors, Madrigal cannot provide any assurances that any of these parties would not breach the agreements to disclose any proprietary information, including trade secrets, and Madrigal may not be able to obtain adequate remedies for such breaches. Further, third parties may still obtain this information by other means, such as breaches of Madrigal's physical or computer security systems. Enforcing a claim that a party illegally disclosed or misappropriated a trade secret is difficult, expensive and time-consuming, and the outcome is unpredictable. Moreover, third parties may come upon this or similar information lawfully and independently. Madrigal would have no right to prevent them, or those to whom they communicate it, from using that technology or information to compete with Madrigal. Further, intellectual property rights have limitations and do not necessarily address all potential threats to Madrigal's competitive position. If any of these events occurs or if Madrigal otherwise loses protection for its trade secrets or proprietary know-how, Madrigal's business may be harmed.

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Madrigal may not be able to protect its intellectual property rights throughout the world.

        While Madrigal has licensed from Roche issued composition-of-matter patents directed at MGL-3196 in the United States and other countries, filing, prosecuting and defending patents on MGL-3196 in all countries throughout the world would be prohibitively expensive, and Madrigal's intellectual property rights in some countries outside the United States can be less extensive than those in the United States. In addition, the laws of some foreign countries may not protect intellectual property rights to the same extent as federal and state laws in the United States. Consequently, Madrigal may not be able to prevent third parties from practicing its inventions in all countries outside the United States, or from selling or importing products made using its inventions in and into the United States or other jurisdictions. Competitors may use Madrigal's technologies in jurisdictions where it has not obtained patent protection to develop their own products and, further, may export otherwise infringing products to territories where Madrigal has patent protection but enforcement is not as strong as that in the United States. These products may compete with MGL-3196, and Madrigal's patents or other intellectual property rights may not be effective or sufficient to prevent them from competing.

        Many companies have encountered significant problems in protecting and defending intellectual property rights in foreign jurisdictions. The legal systems of certain countries, particularly certain developing countries, do not favor the enforcement of patents and other intellectual property protection, particularly those relating to biopharmaceuticals, which could make it difficult for Madrigal to stop the infringement of its patents or marketing of competing products in violation of its proprietary rights generally. Proceedings to enforce Madrigal's patent rights in foreign jurisdictions could result in substantial costs and divert Madrigal's efforts and attention from other aspects of its business, could put its patents at risk of being invalidated or interpreted narrowly and its patent applications at risk of not issuing, and could provoke third parties to assert claims against Madrigal. Madrigal may not prevail in any lawsuits that it initiates, and the damages or other remedies awarded, if any, may not be commercially meaningful. Accordingly, Madrigal's efforts to enforce its intellectual property rights around the world may be inadequate to obtain a significant commercial advantage from the intellectual property that it develops or licenses.

Risks Related to Madrigal's Development, Commercialization and Regulatory Approval

If Madrigal is unable to obtain required regulatory approvals, it will be unable to market and sell its product candidates.

        Madrigal's product candidates are subject to extensive governmental regulations relating to development, clinical trials, manufacturing, oversight of clinical investigators, recordkeeping and commercialization. Rigorous preclinical testing and clinical trials and an extensive regulatory review and approval process are required to be successfully completed in the United States and in each foreign jurisdiction in which Madrigal offers its products before a new drug can be sold in such jurisdictions. Satisfaction of these and other regulatory requirements is costly, time consuming, uncertain, and subject to unanticipated delays. The time required to obtain approval by the FDA, or the regulatory authority in such other jurisdictions is unpredictable and often exceeds five years following the commencement of clinical trials, depending upon the complexity of the product candidate.

        In connection with the clinical development of its product candidates, Madrigal faces risks that:

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        Only a small percentage of product candidates for which clinical trials are initiated receive approval for commercialization. Furthermore, even if Madrigal does receive regulatory approval to market a product candidate, any such approval may be subject to limitations such as those on the indicated uses for which Madrigal may market a particular product candidate.

If Madrigal loses key management personnel, or if Madrigal fails to recruit additional highly skilled personnel, its ability to identify, develop and commercialize products will be impaired.

        Madrigal is highly dependent on its current Chief Executive Officer, Rebecca Taub, M.D., who will transition to the role of Chief Medical Officer and Executive Vice President, Research and Development, of the combined company following the merger. Dr. Taub has significant pharmaceutical industry experience. The loss of Dr. Taub or any other key member of Madrigal's staff would impair Madrigal's ability to identify, develop and market new products. The loss of the services of these key personnel, or the inability to attract and retain additional qualified personnel, could result in delays to development or approval, loss of sales and diversion of management resources. In addition, Madrigal depends on its ability to attract and retain other highly skilled personnel. Competition for qualified personnel is intense, and the process of hiring and integrating such qualified personnel is often lengthy. Madrigal may be unable to recruit such personnel on a timely basis, if at all, which would negatively affect Madrigal's development and commercialization programs.

        Additionally, Madrigal does not currently maintain "key person" life insurance on the lives of Dr. Taub or any other key personnel and does not expect to maintain such a policy for Dr. Taub or Paul A. Friedman, M.D. who is expected to serve as the Chief Executive Officer and Chairman of the combined company following the merger. This lack of insurance means that Madrigal may not receive adequate compensation for the loss of the services of these individuals.

Madrigal currently has no marketing, sales or distribution infrastructure with respect to its product candidates. If Madrigal is unable to develop its sales, marketing and distribution capability on its own or through collaborations with marketing partners, Madrigal will not be successful in commercializing its product candidates.

        Madrigal currently has no marketing, sales or distribution capabilities and has limited sales or marketing experience within its organization. If Madrigal's product candidate, MGL-3196, is approved, Madrigal intends either to establish a sales and marketing organization with technical expertise and supporting distribution capabilities to commercialize MGL-3196, or to outsource this function to a third party. Either of these options would be expensive and time consuming. Some or all of these costs may be incurred in advance of any approval of MGL-3196. In addition, Madrigal may not be able to hire a sales force in the United States that is sufficient in size or has adequate expertise in the medical markets that Madrigal intends to target. Any failure or delay in the development of Madrigal's internal sales, marketing and distribution capabilities would adversely affect the commercialization of MGL-3196 and other future product candidates.

        With respect to Madrigal's existing and future product candidates, Madrigal may choose to collaborate with third parties that have direct sales forces and established distribution systems, either to augment its own sales force and distribution systems or as an alternative to Madrigal's own sales force

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and distribution systems. To the extent that Madrigal enters into co-promotion or other licensing arrangements, Madrigal's product revenue may be lower than if it directly marketed or sold any approved products. In addition, any revenue Madrigal receives will depend in whole or in part upon the efforts of these third parties, which may not be successful and are generally not within Madrigal's control. If Madrigal is unable to enter into these arrangements on acceptable terms or at all, Madrigal may not be able to successfully commercialize any approved products. If Madrigal is not successful in commercializing any approved products, either on its own or through collaborations with one or more third parties, Madrigal's future product revenue will suffer and it may incur significant additional losses.

Even if Madrigal obtains FDA approval of MGL-3196 or any other future product candidate, Madrigal or its partners may never obtain approval or commercialize its products outside of the United States, which would limit Madrigal's ability to realize their full market potential.

        In order to market any products outside of the United States, Madrigal must establish and comply with numerous and varying regulatory requirements of other countries regarding clinical trial design, safety and efficacy. Clinical trials conducted in one country may not be accepted by regulatory authorities in other countries, and regulatory approval in one country does not mean that regulatory approval will be obtained in any other country. Approval procedures vary among countries and can involve additional product testing and validation and additional administrative review periods. Seeking foreign regulatory approvals could result in significant delays, difficulties and costs for Madrigal and may require additional preclinical studies or clinical trials which would be costly and time consuming. Regulatory requirements can vary widely from country to country and could delay or prevent the introduction of Madrigal's products in those countries. Satisfying these and other regulatory requirements is costly, time consuming, uncertain and subject to unanticipated delays. In addition, Madrigal's failure to obtain regulatory approval in any country may delay or have negative effects on the process for regulatory approval in other countries. Madrigal and its partners do not have any product candidates approved for sale in any jurisdiction, including international markets, and Madrigal does not have experience in obtaining regulatory approval in international markets. If Madrigal or its partners fail to comply with regulatory requirements in international markets or to obtain and maintain required approvals, Madrigal's target market will be reduced and its ability to realize the full market potential of its products will be harmed.

If Madrigal does not obtain protection under the Hatch-Waxman Amendments and similar foreign legislation by extending the term of patents covering each of Madrigal's product candidates, Madrigal's business may be materially harmed.

        Depending upon the timing, duration and conditions of FDA marketing approval of Madrigal's product candidates, one or more of Madrigal's United States patents may be eligible for limited patent term extension under the Drug Price Competition and Patent Term Restoration Act of 1984, referred to as the Hatch-Waxman Amendments. The Hatch-Waxman Amendments permit a patent term extension of up to five years for a patent covering an approved product as compensation for effective patent term lost during product development and the FDA regulatory review process. However, Madrigal may not receive an extension if it fails to apply within applicable deadlines, fails to apply prior to expiration of relevant patents or otherwise fails to satisfy applicable requirements. Moreover, the length of the extension could be less than Madrigal requests. If Madrigal is unable to obtain patent term extension or the term of any such extension is less than Madrigal requests, the period during which Madrigal can enforce its patent rights for that product may not extend beyond the current patent expiration dates and Madrigal's competitors may obtain approval to market competing products sooner. As a result, Madrigal's revenue could be potentially materially reduced.

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If Madrigal or its partners market products in a manner that violates fraud and abuse and other healthcare laws, or if Madrigal or its partners violate government price reporting laws, Madrigal or its partners may be subject to administrative civil and/or criminal penalties.

        In addition to FDA restrictions on marketing of pharmaceutical products, several other types of state and federal healthcare laws, including those commonly referred to as "fraud and abuse" laws, have been applied in recent years to restrict certain marketing practices in the pharmaceutical industry. These laws include, among others, false claims and anti-kickback statutes. At such time, if ever, as Madrigal or any of its partners market any of its future approved products, it is possible that some of the business activities of Madrigal and/or its partners could be subject to challenge under one or more of these laws.

        Federal false claims, false statements and civil monetary penalties laws prohibit, among others, any person from knowingly presenting, or causing to be presented, a false claim for payment to the federal government or knowingly making, or causing to be made, a false statement to get a false claim paid. The federal healthcare program anti-kickback statute prohibits, among other things, knowingly and willfully offering, paying, soliciting or receiving remuneration to induce, or in return for, purchasing, leasing, ordering or arranging for the purchase, lease or order of any healthcare item or service reimbursable under Medicare, Medicaid or other federally financed healthcare programs. This statute has been interpreted to apply to arrangements between pharmaceutical manufacturers on the one hand and prescribers, purchasers and formulary managers on the other. Although there are several statutory exceptions and regulatory safe harbors protecting certain common activities from prosecution, the exceptions and safe harbors are drawn narrowly, and practices that involve remuneration intended to induce prescribing, purchasing or recommending may be subject to scrutiny if they do not qualify for an exception or safe harbor.

        In addition, Madrigal and/or its partners may be subject to data privacy and security regulation, including the Health Insurance Portability and Accountability Act of 1996, as amended by the Health Information Technology for Economic and Clinical Health Act, and their respective implementing regulations, which impose specified requirements relating to the privacy, security and transmission of individually identifiable health information.

        Most states also have statutes or regulations similar to these federal laws, which may apply to items such as pharmaceutical products and services reimbursed by private insurers. Madrigal and/or its partners may be subject to administrative, civil and criminal sanctions for violations of any of these federal and state laws. Pharmaceutical and other healthcare companies have been prosecuted under these laws for a variety of promotional and marketing activities, such as: providing free trips, free goods, sham consulting fees and grants and other monetary benefits to prescribers; reporting to pricing services inflated average wholesale prices that were then used by federal programs to set reimbursement rates; engaging in off-label promotion; and submitting inflated best price information to the Medicaid Rebate Program to reduce liability for Medicaid rebates.

Risks Related to Madrigal's Reliance on Third Parties

If the third parties on which Madrigal relies for the conduct of its clinical trials and results do not perform Madrigal's clinical trial activities in accordance with good clinical practices and related regulatory requirements, Madrigal may be unable to obtain regulatory approval for or commercialize its product candidates.

        Madrigal uses third-party service providers to conduct and/or oversee the clinical trials of its product candidates and expects to continue to do so for the foreseeable future. Madrigal relies heavily on these parties for successful execution of its clinical trials. Nonetheless, Madrigal is responsible for confirming that each of its clinical trials is conducted in accordance with FDA requirements and Madrigal's general investigational plan and protocol.

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        The FDA requires Madrigal and its third-party service providers to comply with regulations and standards, commonly referred to as good clinical practices, or GCP, for conducting, recording and reporting the results of clinical trials to assure that data and reported results are credible and accurate, and that the trial participants are adequately protected. Madrigal's reliance on third parties that it does not control does not relieve Madrigal of these responsibilities and requirements. Third parties may not complete activities on schedule or may not conduct Madrigal's clinical trials in accordance with regulatory or GCP requirements or the respective trial plans and protocols. In addition, third parties may not be able to repeat their past successes in clinical trials. The failure of these third parties to carry out their obligations could delay or prevent the development, approval and commercialization of Madrigal product candidates or result in enforcement action against Madrigal.

Madrigal has relied on, and expects to continue to rely on, third-party manufacturers to produce its product candidates.

        Madrigal does not own or operate manufacturing facilities for the production of clinical or commercial quantities of its product candidates, and Madrigal lacks the resources and the capabilities to do so. As a result, Madrigal currently relies, and expects to rely for the foreseeable future, on third-party manufacturers to supply its product candidates. Reliance on third-party manufacturers entails risks to which Madrigal would not be subject if Madrigal manufactured its product candidates or products itself, including:

        If Madrigal does not maintain its key manufacturing relationships, Madrigal may fail to find replacement manufacturers or develop its own manufacturing capabilities, which could delay or impair Madrigal's ability to obtain regulatory approval for its products and substantially increases its costs or deplete profit margins, if any. If Madrigal does find replacement manufacturers, Madrigal may not be able to enter into agreements with them on terms and conditions favorable to it and there could be a substantial delay before new facilities could be qualified and registered with the FDA and other foreign regulatory authorities.

        The FDA and other foreign regulatory authorities require manufacturers to register manufacturing facilities. The FDA and corresponding foreign regulators also inspect these facilities to confirm compliance with current good manufacturing practices, or cGMPs. Contract manufacturers may face manufacturing or quality control problems causing drug substance production and shipment delays or a situation where the contractor may not be able to maintain compliance with the applicable cGMP requirements. Any failure to comply with cGMP requirements or other FDA, European Medicines Agency, or EMA, and comparable foreign regulatory requirements could adversely affect Madrigal's clinical research activities and Madrigal's ability to develop its product candidates and market its products following approval.

        Madrigal's current and anticipated future dependence upon others for the manufacture of its product candidates may adversely affect its future profit margins and its ability to develop its product candidates and commercialize any products that receive regulatory approval on a timely basis.

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Madrigal's reliance on third parties requires it to share its trade secrets, which increases the possibility that a competitor will discover them or that Madrigal's trade secrets will be misappropriated or disclosed.

        Because Madrigal relies on third parties to conduct its clinical trials and to produce its product candidates, Madrigal must, at times, share trade secrets with them. Madrigal seeks to protect its proprietary technology in part by entering into confidentiality agreements and, if applicable, material transfer agreements, consulting agreements or other similar agreements with its third party contractors and consultants prior to disclosing proprietary information. These agreements typically limit the rights of the third parties to use or disclose Madrigal's confidential information, including its trade secrets. Despite the contractual provisions employed when working with third parties, the need to share trade secrets and other confidential information increases the risk that such trade secrets become known by Madrigal's competitors, are inadvertently incorporated into the technology of others, or are disclosed or used in violation of these agreements. Given that Madrigal's proprietary position is based, in part, on its know-how and trade secrets, a competitor's discovery of Madrigal's trade secrets or other unauthorized use or disclosure would impair Madrigal's competitive position and may have a material adverse effect on its business.

Risks Related to the Combined Company

The combined company will incur losses for the foreseeable future and might never achieve profitability.

        The combined company may never become profitable, even if the combined company is able to complete clinical development for one or more product candidates and eventually commercialize such product candidates. The combined company will need to successfully complete significant research, development, testing and regulatory compliance activities that, together with projected general and administrative expenses, is expected to result in substantial increased operating losses for at least the next several years. Even if the combined company does achieve profitability, it may not be able to sustain or increase profitability on a quarterly or annual basis.

The combined company will need to obtain additional funding necessary to support its operations.

        Synta and Madrigal do not know when, or if, the combined company will generate any revenue, and both parties do not expect to generate significant revenue unless and until the combined company obtains regulatory approval of and commercializes one of its current or future product candidates. It is anticipated that the combined company will continue to incur losses for the foreseeable future, and that losses will increase as the combined company continues the development of, and seeks regulatory approvals for, its product candidates, and begins to commercialize any approved products. Based upon current operating plans, it is expected the proceeds from Madrigal's private placement, along with net cash held by Synta upon consummation of the merger, will be able to fund the operations of the combined company through the fourth quarter of 2017. The combined company will require additional capital to complete the development and commercialization of MGL-3196, if approved, and may also need to raise additional funds to pursue other development activities related to additional product candidates.

        Until such time, if ever, as the combined company can generate substantial revenues, it expects to finance its cash needs through a combination of equity or debt financings, collaborations, strategic partnerships or licensing arrangements. However, additional capital may not be available on reasonable terms, if at all. To the extent that the combined company raises additional capital through the sale of stock or convertible debt securities, the ownership interest of its stockholders will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect the rights of its common stockholders. Debt financing, if available, may involve agreements that include increased fixed payment obligations and covenants limiting or restricting the combined company's ability to take specific actions, such as incurring additional debt, making capital expenditures, declaring dividends,

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selling or licensing intellectual property rights, and other operating restrictions that could adversely affect its ability to conduct its business. If the combined company raises additional funds through collaborations, strategic partnerships, or licensing arrangements with third parties, it may have to relinquish valuable rights to MGL-3196 or its other product candidates, including its other technologies, future revenue streams, or research programs, or grant licenses on terms that may not be favorable to it. If the combined company is unable to raise additional funds when needed, it may be required to delay, limit, reduce, or terminate its product development or future commercialization efforts or grant rights to develop and commercialize MGL-3196 or its other product candidates even if it would otherwise prefer to develop and commercialize such product candidates itself.

Synta and Madrigal expect Synta's stock price to be volatile, and the market price of its common stock may drop following the merger.

        The market price of Synta common stock following the merger could be subject to significant fluctuations. Market prices for securities of early-stage pharmaceutical, biopharmaceutical, and other life sciences companies have historically been particularly volatile. Some of the factors that may cause the market price of Synta common stock to fluctuate include:

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        Moreover, the stock markets in general have experienced substantial volatility that has often been unrelated to the operating performance of individual companies. These broad market fluctuations may also adversely affect the trading price of the combined company's common stock.

        In the past, following periods of volatility in the market price of a company's securities, stockholders have often instituted class action securities litigation against those companies. Such litigation, if instituted, could result in substantial costs and diversion of management attention and resources, which could significantly harm the combined company's profitability and reputation.

The failure to integrate successfully the businesses of Madrigal and Synta in the expected timeframe could adversely affect the future results of the combined company following the completion of the merger.

        The success of the merger will depend, in large part, on the ability of the combined company following the completion of the merger to realize the anticipated benefits from combining the businesses of Synta and Madrigal. The continued operation of the two companies will be complex.

        The failure to integrate successfully and to manage successfully the challenges presented by the integration process may result in the combined company's failure to achieve some or all of the anticipated benefits of the merger.

        Potential difficulties that may be encountered in the integration process include the following:

The combined company will incur costs and demands upon management as a result of complying with the laws and regulations affecting public companies.

        The combined company will incur significant legal, accounting and other expenses that Madrigal did not incur as a private company, including costs associated with public company reporting requirements. The combined company will also incur costs associated with corporate governance requirements, including requirements under the Sarbanes-Oxley Act and rules and regulations promulgated by the SEC and The NASDAQ Stock Market. These rules and regulations are expected to increase the combined company's legal and financial compliance costs and to make some activities more time-consuming and costly. For example, not all members of the combined company's management team have previously managed and operated a public company. The executive officers and other personnel of the combined company will need to devote substantial time to gaining expertise regarding operations as a public company and compliance with applicable laws and regulations. These rules and regulations may also make it difficult and expensive for the combined company to obtain directors' and officers' liability insurance. As a result, it may be more difficult for the combined company to attract and retain qualified individuals to serve on the combined company's board of directors or as executive officers of the combined company, which may adversely affect investor

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confidence in the combined company and could cause the combined company's business or stock price to suffer.

Anti-takeover provisions in the combined company's charter documents and under Delaware law could make an acquisition of the combined company more difficult and may prevent attempts by the combined company stockholders to replace or remove the combined company management.

        Provisions in the combined company's certificate of incorporation and bylaws, which are identical to Synta's certificate of incorporation and bylaws, may delay or prevent an acquisition or a change in management. These provisions include a classified board of directors. In addition, because the combined company will be incorporated in Delaware, it is governed by the provisions of Section 203 of the DGCL, which prohibits stockholders owning in excess of 15% of the outstanding combined company voting stock from merging or combining with the combined company. Although Synta and Madrigal believe these provisions collectively will provide for an opportunity to receive higher bids by requiring potential acquirors to negotiate with the combined company's board of directors, they would apply even if the offer may be considered beneficial by some stockholders. In addition, these provisions may frustrate or prevent any attempts by the combined company's stockholders to replace or remove then current management by making it more difficult for stockholders to replace members of the board of directors, which is responsible for appointing members of management.

Synta and Madrigal do not anticipate that the combined company will pay any cash dividends in the foreseeable future.

        The current expectation is that the combined company will retain its future earnings to fund the development and growth of the combined company's business. As a result, capital appreciation, if any, of the common stock of the combined company will be your sole source of gain, if any, for the foreseeable future.

The pro forma financial statements are presented for illustrative purposes only and may not be an indication of the combined company's financial condition or results of operations following the completion of the merger.

        The pro forma financial statements contained in this proxy statement are presented for illustrative purposes only and may not be an indication of the combined company's financial condition or results of operations following the merger for several reasons. The pro forma financial statements have been derived from the historical financial statements of Synta and Madrigal and adjustments and assumptions have been made regarding the combined company after giving effect to the merger. The information upon which these adjustments and assumptions have been made is preliminary, and these kinds of adjustments and assumptions are difficult to make with accuracy. Moreover, the pro forma financial statements do not reflect all costs that are expected to be incurred by the combined company in connection with the merger. For example, the impact of any incremental costs incurred in integrating the two companies is not reflected in the pro forma financial statements. As a result, the actual financial condition of the combined company following the merger may not be consistent with, or evident from, these pro forma financial statements. The assumptions used in preparing the pro forma financial information may not prove to be accurate, and other factors may affect the combined company's financial condition following the transaction. See "Unaudited Pro Forma Condensed Combined Financial Statements" beginning on page 226 of this proxy statement.

Future sales of shares by existing stockholders could cause the combined company's stock price to decline.

        If existing stockholders of Synta and Madrigal sell, or indicate an intention to sell, substantial amounts of the combined company's common stock in the public market after the post-merger lock-up and other legal restrictions on resale discussed in this proxy statement lapse, the trading price of the common stock of the combined company could decline. Upon completion of the merger, the combined

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company is expected to have outstanding a total of approximately 396.7 million shares of common stock. As of immediately following the closing of the merger, approximately 117.7 million shares of common stock will be freely tradable, without restriction, in the public market.

        The lock-up agreements entered into between each of Synta and Madrigal and certain of each other's securityholders provide that the shares subject to the lock-up restrictions will be released from such restrictions 180 days from the closing date of the merger. Based on shares outstanding as of April 13, 2016 and assuming that a registration statement covering the resale of the shares of Synta common stock issuable in connection with the merger is in effect, up to an additional approximately 253.9 million shares of common stock will be eligible for sale in the public market. Nearly all of these shares will be held by directors, executive officers of the combined company and other affiliates and will be subject to volume limitations under Rule 144 under the Securities Act.

The ownership of the combined company's capital stock will be highly concentrated, which may prevent other stockholders from influencing significant corporate decisions and may result in conflicts of interest that could cause the combined company's stock price to decline.

        Investment entities and individuals affiliated with Bay City Capital, LLC, or Bay City Capital, of which Dr. Craves, an anticipated director of the combined company, is a managing director, are expected to beneficially own or control approximately 52.5% of the outstanding shares of the combined company's outstanding common stock following the completion of the merger. Accordingly, Bay City Capital will exert substantial influence over the combined company and the outcome of corporate actions requiring stockholder approval, including the election of directors, any merger, consolidation or sale of all or substantially all of the combined company's assets or any other significant corporate transactions. This stockholder may also delay or prevent a change of control of the combined company, even if such a change of control would benefit the other stockholders of the combined company. The significant concentration of stock ownership may adversely affect the trading price of the combined company's capital stock due to investors' perception that conflicts of interest may exist or arise.

Even if the combined company's product candidates are successful in clinical trials, the combined company may not be able to successfully commercialize them, which may adversely affect the combined company's future revenues and financial condition.

        Madrigal has dedicated substantially all of its resources to the research and development of its product candidates. At present, Madrigal is focusing its resources on MGL-3196 while strategically conducting development activities on the remainder of its other future product candidates. Madrigal's primary product candidate, MGL-3196, is currently in the early stages of clinical development. The combined company may not develop any product candidates suitable for commercialization.

        Prior to commercialization, each product candidate will require significant additional research, development and preclinical testing and extensive clinical investigation before submission of any regulatory application for marketing approval. Potential products that appear to be promising at early stages of development may not reach the market for a number of reasons, including that they may:

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        The combined company's product development efforts or the combined company's collaborative partners' efforts may not be successfully completed for any product candidate, and the combined company may not obtain any required regulatory approvals or successfully commercialize a product candidate even if clinical development for such product candidate is successfully completed. Any products, if introduced, may not be successfully marketed nor achieve customer acceptance, which may adversely affect the combined company's future revenues and financial condition.

Because the merger will result in an ownership change under Section 382 of the Internal Revenue Code, or the Code, for Synta, Synta's pre-merger net operating loss carryforwards and certain other tax attributes will be subject to limitations. The net operating loss carryforwards and other tax attributes of Madrigal and of the combined company may also be subject to limitations as a result of ownership changes.

        If a corporation undergoes an "ownership change" within the meaning of Section 382 of the Code, the corporation's net operating loss carryforwards and certain other tax attributes arising from before the ownership change are subject to limitations on use after the ownership change. In general, an ownership change occurs if there is a cumulative change in the corporation's equity ownership by certain stockholders that exceeds fifty percentage points over a rolling three-year period. Similar rules may apply under state tax laws. The merger will result in an ownership change for Synta and, accordingly, Synta's net operating loss carryforwards and certain other tax attributes will be subject to limitations (or disallowance) on their use after the merger. Madrigal's net operating loss carryforwards may also be subject to limitation as a result of prior shifts in equity ownership and/or the merger. Additional ownership changes in the future could result in additional limitations on Synta's, Madrigal's and the combined company's net operating loss carryforwards. Consequently, even if the combined company achieves profitability, it may not be able to utilize a material portion of Synta's, Madrigal's or the combined company's net operating loss carryforwards and other tax attributes, which could have a material adverse effect on cash flow and results of operations.

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FORWARD-LOOKING STATEMENTS

        This proxy statement and the documents incorporated by reference into this proxy statement contain forward-looking statements relating to Synta, Madrigal and the merger. These forward-looking statements are based on current expectations and beliefs and involve numerous risks and uncertainties that could cause actual results to differ materially from expectations. These forward-looking statements should not be relied upon as predictions of future events as we cannot assure you that the events or circumstances reflected in these statements will be achieved or will occur. You can identify forward-looking statements by the use of forward-looking terminology including "believes," "expects," "may," "will," "should," "seeks," "intends," "plans," "pro forma," "estimates," or "anticipates" or the negative of these words and phrases or other variations of these words and phrases or comparable terminology. All statements other than statements of historical fact are statements that could be deemed forward-looking statements. For example, forward-looking statements include any statements regarding the strategies, prospects, plans, expectations or objectives of management of Synta or Madrigal for future operations, the progress, scope or duration of the development of product candidates or programs, the benefits that may be derived from product candidates or the commercial or market opportunity in any target indication, the ability of Synta or Madrigal to protect intellectual property rights, the anticipated operations, financial position, revenues, costs or expenses of Synta, Madrigal or the combined company, statements regarding future economic conditions or performance, statements of belief and any statement of assumptions underlying any of the foregoing. Forward looking statements may also include any statements regarding the approval and closing of the merger, including the timing of the merger, Synta's ability to solicit a sufficient number of proxies to approve the merger, other conditions to the completion of the merger, the expected benefits of the merger, and any statement of assumptions underlying any of the foregoing.

        For a discussion of the factors that may cause Synta, Madrigal or the combined company's actual results, performance or achievements to differ materially from any future results, performance or achievements expressed or implied in such forward-looking statements, or for a discussion of risk associated with the ability of Synta and Madrigal to complete the merger and the effect of the merger on the business of Synta, Madrigal and the combined company, see "Risk Factors" beginning on page 26. Additional factors that could cause actual results to differ materially from those expressed in the forward-looking statements are discussed in reports filed with the SEC by Synta. See "Where You Can Find More Information" beginning on page 246. There can be no assurance that the merger will be completed, or if it is completed, that it will close within the anticipated time period or that the expected benefits of the merger will be realized.

        If any of these risks or uncertainties materializes or any of these assumptions proves incorrect, the results of Synta, Madrigal or the combined company could differ materially from the forward-looking statements. All forward-looking statements in this proxy statement are current only as of the date on which the statements were made. Synta and Madrigal do not undertake any obligation to publicly update any forward-looking statement to reflect events or circumstances after the date on which any statement is made or to reflect the occurrence of unanticipated events.

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THE ANNUAL MEETING OF SYNTA STOCKHOLDERS

Date, Time and Place

        The Annual Meeting will be held on [·], 2016, at the offices of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., One Financial Center, Boston, MA 02111, commencing at [·], local time. Synta is sending this proxy statement to its stockholders in connection with the solicitation of proxies by the Synta board of directors for use at the Annual meeting and any adjournments or postponements of the Annual Meeting. This proxy statement is first being sent to stockholders of Synta on or about [·], 2016.

Purposes of the Annual Meeting

        The purposes of the Annual Meeting are:

        Proposal Nos. 1 and 2 are being submitted to stockholders pursuant to the terms of the Merger Agreement. Proposal No. 3 is conditioned upon the approval of Proposal Nos. 1 and 2.

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Recommendation of the Synta Board of Directors

        The Synta board of directors has determined and believes that the Merger Agreement and the issuance of shares of Synta common stock by virtue of the merger is advisable to and in the best interests of, Synta and its stockholders and has approved such items. The Synta board of directors unanimously recommends that Synta stockholders vote "FOR" Proposal No. 1 to approve the Merger Agreement and the issuance of shares of Synta common stock by virtue of the merger.

        The Synta board of directors has determined and believes that it is advisable to, and in the best interests of, Synta and its stockholders to approve the amendment to the restated certificate of incorporation of Synta effecting the proposed reverse stock split, as described in this proxy statement. The Synta board of directors unanimously recommends that Synta stockholders vote "FOR" Proposal No. 2 to approve the amendment to the restated certificate of incorporation of Synta effecting the proposed reverse stock split, as described in this proxy statement.

        The Synta board of directors has determined and believes that it is advisable to, and in the best interests of, Synta and its stockholders to approve the amendment to the 2015 Stock Plan to increase the total number of shares of Synta common stock currently available for issuance under the 2015 Stock Plan, as described in this proxy statement. The Synta board of directors unanimously recommends that Synta stockholders vote "FOR" Proposal No. 3 to approve the amendment to the 2015 Stock Plan to increase the total number of shares of Synta common stock currently available for issuance under the 2015 Stock Plan, as described in this proxy statement.

        The Synta board of directors has determined and believes that the election of Bruce Kovner as a Class III director for a three-year term to expire at the 2019 Synta annual stockholders meeting is advisable to, and in the best interests of, Synta and its stockholders and has approved and adopted the proposal. The Synta board of directors unanimously recommends that Synta stockholders vote "FOR" Proposal No. 4 to elect one Class III director, Bruce Kovner, for a three-year term to expire at the 2019 Synta annual stockholders meeting provided, however, that, if the merger is completed, the Synta board of directors will be reconstituted as provided in the Merger Agreement.

        The Synta board of directors has determined and believes that it is advisable to, and in the best interests of, Synta and its stockholders to approve, on an advisory basis, the compensation of Synta's named executive officers. The Synta board of directors unanimously recommends that Synta stockholders vote "FOR" Proposal No. 5 to approve the compensation of Synta's named executive officers as disclosed in this proxy statement.

        The Synta board of directors has determined and believes that it is advisable to, and in the best interests of, Synta and its stockholders to approve, on an advisory basis, the golden parachute compensation that may be paid or become payable to Synta's named executive officers. The Synta board of directors unanimously recommends that Synta stockholders vote "FOR" Proposal No. 6 to approve the golden parachute compensation of Synta's named executive officers as disclosed in this proxy statement.

        The Synta board of directors has determined and believes that the ratification of the selection of Ernst & Young LLP as Synta's independent registered public accounting firm for the fiscal year ending December 31, 2016 is advisable to, and in the best interests of, Synta and its stockholders and has approved such ratification. The Synta board of directors unanimously recommends that Synta stockholders vote "FOR" Proposal No. 7 to ratify the selection of Ernst & Young LLP as Synta's independent registered public accounting firm for the fiscal year ending December 31, 2016.

        The Synta board of directors has determined and believes that adjourning the Annual Meeting, if necessary, to solicit additional proxies if there are not sufficient votes in favor of Proposal Nos. 1, 2 and 3 is advisable to, and in the best interests of, Synta and its stockholders and has approved and adopted the proposal. The Synta board of directors unanimously recommends that Synta stockholders vote

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"FOR" Proposal No. 8 to adjourn the Annual Meeting, if necessary, to solicit additional proxies if there are not sufficient votes in favor of Proposal Nos. 1, 2 and 3.

Record Date and Voting Power

        Only holders of record of Synta common stock at the close of business on the record date, [·], 2016, are entitled to notice of, and to vote at, the Annual Meeting. There were approximately [·] holders of record of Synta common stock at the close of business on the record date. At the close of business on the record date, [·] shares of Synta common stock were issued and outstanding. Each share of Synta common stock entitles the holder thereof to one vote on each matter submitted for stockholder approval. See the section entitled "Principal Stockholders of Synta" beginning on page 238 for information regarding persons known to the management of Synta to be the beneficial owners of more than 5% of the outstanding shares of Synta common stock.

Voting and Revocation of Proxies

        The proxy accompanying this proxy statement is solicited on behalf of the board of directors of Synta for use at the Annual Meeting.

        If you are a stockholder of record of Synta as of the record date referred to above, you may vote in person at the Annual Meeting or vote by proxy using the enclosed proxy card. Whether or not you plan to attend the Annual Meeting, Synta urges you to vote by proxy to ensure your vote is counted. You may still attend the Annual Meeting and vote in person if you have already voted by proxy. As a stockholder of record you may vote:

        Telephone and Internet voting facilities for stockholders of record will be available 24-hours a day and will close at 1:00 a.m., Central Time, on [·], 2016.

        If your Synta shares are held by your broker as your nominee, that is, in "street name," you should receive voting instructions from the bank, broker or other nominee that holds your shares. If you do not give instructions to your broker, your broker can vote your Synta shares with respect to "discretionary" items but not with respect to "non-discretionary" items. Discretionary items are proposals considered routine under the rules of The New York Stock Exchange on which your broker may vote shares held in "street name" in the absence of your voting instructions. On non-discretionary items for which you do not give your broker instructions, the Synta shares will be treated as broker non-votes.

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        All properly executed proxies that are not revoked will be voted at the Annual Meeting and at any adjournments or postponements of the Annual Meeting in accordance with the instructions contained in the proxy. If a holder of Synta common stock executes and returns a proxy and does not specify otherwise, the shares represented by that proxy will be voted "FOR" Proposal No. 1 to approve the Merger Agreement and the issuance of shares of Synta common stock in the merger; "FOR" Proposal No. 2 to approve the amendment to the restated certificate of incorporation of Synta effecting the proposed reverse stock split described in this proxy statement; "FOR" Proposal No. 3 to approve the amendment to the 2015 Stock Plan to increase the total number of shares of Synta common stock currently available for issuance; "FOR" Proposal No. 4 to elect Bruce Kovner as a Class III director for a three-year term to expire at the 2019 Synta annual stockholders meeting, provided, however, that, if the merger is completed, the Synta board of directors will be reconstituted as provided in the Merger Agreement; "FOR" Proposal No. 5 to approve, on an advisory basis, the compensation of Synta's named executive officers; "FOR" Proposal No. 6 to approve, on an advisory basis, the golden parachute compensation that may be paid or become payable to Synta's named executive officers; "FOR" Proposal No. 7 to ratify the selection of Ernst & Young LLP as Synta's independent registered public accounting firm for the year ending December 31, 2016; and "FOR" Proposal No. 8 to adjourn the Annual Meeting, if necessary, to solicit additional proxies if there are not sufficient votes in favor of Proposal Nos. 1, 2 and 3 in accordance with the recommendation of the Synta board of directors.

        Unless you are a Synta stockholder who executed a voting agreement, you may change your vote or revoke your proxy at any time before your proxy is voted at the Annual Meeting in any one of the following ways:

        The vote that you submit latest and still timely is the vote that will be counted.

        If you are a Synta stockholder of record or a stockholder who owns Synta shares in "street name" and have instructed a broker to vote your shares of Synta common stock, you must follow directions received from your broker to change your vote or revoke your proxy.

Required Vote

        The presence, in person or represented by proxy, at the Annual Meeting of the holders of a majority of the shares of Synta common stock outstanding and entitled to vote at the Annual Meeting is necessary to constitute a quorum at the meeting. Abstentions and broker non-votes will be counted towards a quorum. Approval of Proposal Nos. 1 (with abstentions having the same effect as votes against Proposal No. 1), 3, 5, 6, 7 and 8 requires the affirmative vote of the holders of a majority of the

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shares of Synta common stock present in person or represented by proxy at the Annual Meeting and entitled to vote on the proposal. Approval of Proposal No. 2 requires the affirmative vote of holders of a majority of the Synta common stock outstanding on the record date for the Annual Meeting. For Proposal No. 4, directors are elected by a plurality of the affirmative votes cast by those shares present in person, or represented by proxy, and entitled to vote at the Annual Meeting. The nominees for director receiving the highest number of affirmative votes will be elected.

        Votes will be counted by the inspector of election appointed for the meeting, who will separately count "FOR" and "AGAINST" votes, abstentions and broker non-votes. Abstentions will be counted towards the vote total for each proposal and will have the same effect as "AGAINST" votes for Proposal Nos. 1 and 2, but will have no effect on Proposal Nos. 3, 4, 5, 6, 7 and 8. Broker non-votes will have the same effect as "AGAINST" votes for Proposal No. 2, but will have no effect on Proposal Nos. 1, 3, 4, 5, 6, 7 and 8.

        The directors, executive officers and several major stockholders of Synta, owning a combined 18.2% of the shares of Synta common stock entitled to vote at the Annual Meeting, are subject to voting agreements. Each stockholder that entered into a voting agreement has agreed to vote all shares of Synta common stock owned by such stockholders as of the record date in favor of the issuance of Synta common stock in the merger as contemplated by the Merger Agreement, the adoption of the Merger Agreement if submitted for adoption, the approval of any proposal to adjourn or postpone the meeting to a later date, if there are not sufficient votes for the issuance of Synta as contemplated by the Merger Agreement on the date on which such meeting is held, and any other matter necessary to complete the transactions contemplated by the Merger Agreement that are considered and voted upon by Synta's stockholders and against any "acquisition proposal," as defined in the Merger Agreement. Synta and Madrigal are not aware of any affiliate of Madrigal, other than Drs. Friedman and Taub, owning any shares of Synta common stock entitled to vote at the Annual Meeting.

Solicitation of Proxies

        In addition to solicitation by mail, the directors, officers, employees and agents of Synta may solicit proxies from Synta stockholders by personal interview, telephone, telegram or otherwise. Arrangements will also be made with brokerage firms and other custodians, nominees and fiduciaries who are record holders of Synta common stock for the forwarding of solicitation materials to the beneficial owners of Synta common stock. Synta will reimburse these brokers, custodians, nominees and fiduciaries for the reasonable out-of-pocket expenses they incur in connection with the forwarding of solicitation materials. We have engaged The Proxy Advisory Group, LLC to advise us on certain proposals in this proxy statement. We have engaged The Proxy Advisory Group, LLC to assist in the solicitation of proxies and provide related advice and informational support, for a services fee and the reimbursement of customary disbursements that are not expected to exceed $25,000 in the aggregate.

Other Matters

        As of the date of this proxy statement, the Synta board of directors does not know of any business to be presented at the Annual Meeting other than as set forth in the notice accompanying this proxy statement. If any other matters should properly come before the Annual Meeting, it is intended that the shares represented by proxies will be voted with respect to such matters in accordance with the judgment of the persons voting the proxies.

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THE MERGER

        This section and the section entitled "The Merger Agreement" beginning on page 98 describe the material aspects of the merger, including the Merger Agreement. While Synta and Madrigal believe that this description covers the material terms of the merger and the Merger Agreement, it may not contain all of the information that is important to you. You should read carefully this entire proxy statement for a more complete understanding of the merger and the Merger Agreement, including the Merger Agreement attached as Annex A, the opinion of Roth Capital Partners, LLC attached as Annex B, and the other documents to which you are referred herein. See the section entitled "Where You Can Find More Information" beginning on page 246.

Background of the Merger

        On October 20, 2015, Synta Pharmaceuticals Corp., or Synta, announced the termination of its Phase 3 clinical trial in lung cancer, or the GALAXY-2 trial. This trial related to Synta's most advanced program—its leading product candidate, ganetespib, in the second-line treatment of patients with advanced non-small cell lung adenocarcinoma. After review of the pre-planned interim analysis, the study's Independent Data Monitoring Committee, or IDMC, concluded that the addition of ganetespib to docetaxel was unlikely to demonstrate a statistically significant improvement in the primary endpoint of overall survival compared to docetaxel alone. Based on such results, Synta announced it was terminating the GALAXY-2 trial and undertaking a comprehensive review of its strategy going forward.

        Immediately following this announcement, Synta began to evaluate measures to preserve its cash while maximizing stockholder value during the review process, including various reductions in workforce scenarios and the potential for monetizing any remaining research and development programs.

        On October 30, 2015, the Synta board of directors voted (i) to expand the board to include Scott Morenstein, an executive with extensive experience in the life sciences industry and in strategic transactions, and a managing director of CAM Capital (an affiliate of Caxton Corporation, an approximate 15% stockholder of Synta) and (ii) establish a special committee of the board of directors, or the Business Strategy Committee, consisting of directors Paul A. Friedman, M.D., Keith R. Gollust, Bruce Kovner, Scott Morenstein and Chen Schor, Synta's Chief Executive Officer. The purpose of the Business Strategy Committee was to provide additional board oversight and assistance in the strategy review, especially with respect to the exploration of any possible strategic transaction.

        While the strategic review would include the evaluation of all reasonable options to maximize value for Synta stockholders, including (i) the viability of continuing research and clinical activity with ganetespib in other indications and exploiting Synta's heat shock protein 90 (Hsp90) inhibitor Drug Conjugate, or HDC, program, (ii) the potential for monetizing or further developing any of Synta's remaining research and development programs, (iii) possible business combinations with other oncology-focused public companies and (iv) the possibility of liquidating Synta and distributing any remaining cash to stockholders, it was perceived that the best way to maximize value for Synta's stockholders may be through a merger of Synta with a private life sciences company, with Synta's stock being the consideration in the transaction. This view was supported by the failure of Synta's own clinical program, the lack of value that the marketplace seemed to assign to its remaining non-cash assets and the value that Synta's public listing and cash might have to attract a high-quality merger candidate seeking to advance of its own clinical program(s). Such a reverse merger transaction could provide Synta stockholders with a meaningful stake in a combined company possessing both promising clinical prospects and the means to pursue them, establishing the opportunity for long-term value creation for Synta stockholders.

        Furthermore, at the time, the public markets for clinical stage life sciences companies was beginning to deteriorate, including the eventual collapse of the initial public offering, or IPO market

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for such companies later in the year. As a result, there was a perception that high-quality private life sciences companies may be actively seeking such business combinations and that Synta had an opportunity to deliver value to its stockholders in this manner if it could act within an acceptable timeframe and manage its cash and other resources accordingly. For these reasons, the Synta board of directors focused its efforts on a search to identify such merger candidates. Initial search efforts started with inbound contacts from companies to Synta's management following the GALAXY-2 announcement and selected ideas by various investment bankers and other referrals, and became a systematic review once Synta formally engaged an investment banking firm to conduct a broad market process, as described below.

        On November 5, 2015, Synta announced (i) its third quarter operating results, (ii) the appointment of Mr. Morenstein to the board of directors and (iii) a reduction in workforce. As a result of the termination of GALAXY-2, Synta initiated a restructuring process to reduce costs and conserve cash, reducing its workforce by approximately 60% to 33 full time employees. It also reiterated its ongoing strategic review.

        During November, Synta management had been in discussions with investment banking firm MTS Health Partners, L.P., or MTS about potentially assisting Synta in conducting a broad market search. In addition to being a well-known investment bank specializing in the life sciences industry, MTS had been involved in similar situations, including recent reverse merger transactions involving life sciences companies. During this period, MTS, in consultation with Synta's senior management, identified approximately 1,000 potential merger candidates, which subsequently was narrowed to approximately 110 companies that were evaluated in some detail. Some of the criteria used in this process included: (i) current, soon-to-be and previously-filed IPO candidates, (ii) companies that recently completed financing rounds with known crossover investors and (iii) companies pursuing the development of treatments in therapeutic areas garnering significant attention from life sciences investors.

        On November 30, 2015, Synta formally engaged MTS to provide financial advisory services, including conducting a broad market search to identify and reach out to suitable merger candidates. MTS recommended a two-step strategic review process, with an initial phase involving MTS issuing a process letter to parties to solicit non-binding initial indications of interest, with such indications of interest to summarize the counterparty's business plan, proposed ownership split of the combined company, estimated financing needs and other matters. Following the receipt of indications of interest, the Business Strategy Committee would then review the indications of interest to focus on selecting a subset to progress to the next round of consideration. Such next round would include in-person presentations by the management teams of such semi-finalists to the full Synta board of directors, further due diligence (including two-way due diligence) and refinement of the indication of interests. Thereafter, the Synta board of directors could select a finalist with whom to focus Synta's limited time and resources to negotiate a definitive merger agreement.

        On December 7, 2015, at a Synta board of directors meeting, representatives from MTS and Synta management outlined the process above and described the steps taken to date to identify and reach out to suitable merger candidates. Mr. Schor generally described the kinds of companies under evaluation and the range of development stages. Specific companies were then discussed in detail, including ones that were excluded from further consideration and ones that remained under active consideration, in an effort to narrow the field from approximately 110 to a more manageable number to be sent bid request letters.

        Based on these discussions, beginning on December 10, 2015, 22 companies were sent bid request letters with an initial due date to submit an indication of interest by December 24, 2015. Each of these companies had entered into a confidentiality agreement with Synta.

        Madrigal Pharmaceuticals, Inc., or Madrigal, was selected as one of these 22 companies to be invited to submit an indication of interest because it fit the search criteria, being a private life sciences

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company with promising clinical program(s) in an increasingly active area of the industry. Dr. Friedman excluded himself from the board's discussion of Madrigal in accordance with the corporate governance considerations described below.

        At the outset, it was recognized that consideration of Madrigal as a potential merger candidate (and its potential participation in this process) would require special corporate governance procedures and considerations, given the following relationships:

These relationships were fully disclosed to, and discussed among, the Synta board of directors at the outset. After consultation with Synta's General Counsel (and later Synta's outside legal counsel), the board determined that any related party or conflict of interest issues raised by these relationships could be appropriately managed by carefully limiting Dr. Friedman's participation in board deliberations and communications, and eventually excluding him entirely from such participation were Madrigal to progress in the process. With respect to Synta's financial advisor, the board was satisfied proceeding with MTS based on its reputation; the board's confidence that a broad and objective process of identifying and evaluating merger candidates would be conducted, whether or not Madrigal participated; and the fact the MTS engagement letter with Synta specifically enabled Synta to hire a separate, independent investment banker to provide a fairness opinion if a transaction with Madrigal were to occur and provided a reduction in the fees payable by Synta to MTS in such event.

        By late December 2015, 11 companies had submitted indications of interests, including Madrigal (out of the 22 bid request letters that MTS sent earlier in the month). These companies focused their clinical programs in a variety of indications and markets.

        On January 4, 2016, a meeting of the Business Strategy Committee was held, at which representatives from MTS and Synta management formally reviewed with the Committee these indications of interest, with the purpose of selecting a subset to advance to the next round of consideration. Detailed information about each of the companies and their indications of interest was discussed, including (i) company-specific value drivers, such as descriptions of clinical programs and estimates of the probability of success at various milestones and timing, the market and competitive landscape, investor base, potential fund-raising ability to support programs and readiness to operate as the management team of a public company, and (ii) transaction-specific value drivers, such as the valuation of the private company, the proposed post-closing stock ownership split (i.e., what percentage ownership would Synta's stockholders continue to own in the company) and the ability to close a transaction.

        On January 4, 2016, following this discussion and based on Synta's and MTS's diligence and discussions with potential strategic partners, the Business Strategy Committee unanimously agreed to narrow the focus of the process to four companies: Companies A, B, and C and Madrigal, or collectively, the Four Finalists. Pursuant to the corporate governance consideration described above, Dr. Friedman excluded himself from the board's discussion of Madrigal.

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        The Four Finalists represented companies focused on a variety of indications and their initial proposals offered Synta stockholders post-closing stock ownership opportunities ranging from 23.1% to 33.3% in such entities.

        On January 18, 2016, MTS sent the Four Finalists second round bid request letters, inviting each company to make an in-person management presentation to Synta's full board of directors on January 25, 2016. Each company was instructed to address specific, tailored due diligence or other follow-up questions, prepare a detailed presentation covering certain topics and sharpen the terms of their indication of interest (including valuation, financing plans and post-closing stockownership split).

        With respect to Madrigal, it specifically was communicated that one area it needed to address was the readiness of the Madrigal management team to lead a public company. In response, it was proposed by Dr. Friedman and Fred Craves, Ph.D. of Bay City Capital that, if Madrigal was chosen, Dr. Friedman would have some formal role at Madrigal post-closing to address these concerns. This suggestion was made because of Dr. Friedman's experience running publicly traded life sciences companies. Specifically, it was proposed that Dr. Friedman would become the Executive Chairman of Madrigal.

        On January 25, 2016, the Synta board of directors, members of Synta's management team, Synta's MTS representatives and a representative from Synta's outside legal counsel, Mintz, Levin, Cohn, Ferris, Glovsky, and Popeo P.C., or Mintz Levin, met in-person with the management teams of each of the Four Finalists at Mintz Levin's offices in New York City. The purpose of the meetings was to evaluate the Four Finalists and select among them two semi-finalists to progress to the next stage of the process. The format of these meetings consisted of each company presenting to the full board and other attendees for approximately 90 minutes, including a sub-period for each team to have discussions with the board of directors without any Synta management present.

        Based on guidelines established by Chairman Gollust and Synta's General Counsel, in consultation with Mintz Levin, it was determined that Dr. Friedman would participate in each session, including the Madrigal session at which Dr. Taub and her management team would present, but that Dr. Friedman would be excluded from the ultimate deliberations of the board of directors and the vote to determine semi-finalists at the meeting.

        At the conclusion of this meeting, there was consensus among Synta's board of directors and management team that, at this time, it would not be in the best interests of Synta stockholders to continue to evaluate Company A and B in this process, given the determination that a business combination with either of them would not be as attractive for creating long-term stockholder value as a transaction with either Company C or Madrigal. Some of the concerns expressed related to (i) the quality, timing and/or prospects of clinical programs, (ii) perceived lack of investor support, (iii) competitive landscape and (iv) management team considerations.

        On the other hand, there was consensus in favor of Company C and Madrigal being advanced as semi-finalists in the board's next meeting to be held on February 7, 2016.

        Following the meeting on January 25, 2016, MTS informed each of the companies of the outcome, and Synta and its advisors pressed certain points and sought additional information/feedback from Company C and Madrigal to help differentiate between their proposals, including:

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        Based on telephone conversations and other communications between Dr. Friedman, Fred Craves, Ph.D., and Chairman Gollust occurring from January 26, 2016 to February 7, 2016, Madrigal agreed to revise its proposal as follows: (i) to alleviate concerns about the management team, Dr. Friedman would commit himself to be the full time Chief Executive Officer of Madrigal and Chairman of the Madrigal board of directors, if Madrigal was chosen; Dr. Taub would serve as the Chief Scientific Officer (or similar capacity) and would also be on the board; (ii) prior to, or concurrent with, the signing of any definitive merger agreement, Madrigal would raise approximately $15 million ($5 million from Dr. Friedman and $10 million from an identified third party investor) and (iii) Madrigal agreed to lower its valuation as follows: a total valuation of $85 million, consisting of a $60 million base valuation, $15 million of new equity and a $10 million option pool.

        Between January 26, 2016 and February 7, 2016, efforts were made by Synta's MTS representatives to engage Company C representatives with respect to concessions on its valuations but received a limited response.

        On February 7, 2016, a telephonic meeting of the Synta board of directors was held for the purpose of (i) determining whether Company C or Madrigal should be selected as the finalist with whom to negotiate the terms of a definitive merger agreement (which would be subject to final board approval), (ii) discussing any other viable potential courses of action for the Company, including liquidation and (iii) considering implementing an additional reduction in workforce. Attendees included all members of the Synta board of directors (except Dr. Friedman who was excluded in accordance with the corporate governance consideration described above), members of Synta's management team, Synta's MTS representatives and a representative from Mintz Levin.

        At the beginning of the meeting, the representative from Mintz Levin reviewed for the board their fiduciary duties, including duty of care, duty of loyalty and duties in a change of control transaction, and the applicable judicial review standards. In that connection, the following points were reiterated (i) the broad market check conducted by MTS and Synta, (ii) the corporate governance safeguards the board had taken, and would continue to take, with respect to Dr. Friedman's relationship with Madrigal and (iii) the rigorous involvement of the rest (all of whom are disinterested directors) of the Synta board of directors in the process, especially Chairman Gollust and director Scott Morenstein. The possibility of non-deal alternatives, such as liquidation, was also discussed.

        Various updates since January 25, 2016 were discussed in detail by the board of directors including:

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        The board discussed the related-party aspect of doing any transaction with Madrigal. The board emphasized its view that having Dr. Friedman committed to be the Chief Executive Officer of the combined entity would be a significant positive benefit for stockholder value maximization, given Dr. Friedman's track record of success. As such, the board viewed the substantive benefits of this feature of a transaction with Madrigal as outweighing the added complexity of addressing the related-party aspects. Lastly, it was also acknowledged that any transaction with Madrigal would entail hiring a separate financial advisor to provide a fairness opinion on customary terms.

        Based on the foregoing, there was unanimous consensus among the Synta board of directors that it would be in the best interests of Synta stockholders to focus on negotiating a definitive merger agreement with Madrigal, whose terms would be subject to the final approval of the board of directors. On February 7, 2016, Madrigal was chosen as the finalist.

        On February 8, 2016, representatives of MTS informed Madrigal that it was selected as the finalist with whom Synta would focus on negotiating a definitive merger agreement, and Company C was informed that Synta had decided not to proceed with Company C at that time.

        Synta did not grant Madrigal any exclusive negotiation period during which Synta would be limited in its ability to have discussions with other parties. Nor did Synta subject any of the potential merger candidates to any standstill agreements; accordingly, any such parties would have been, and are, free to re-approach Synta with any interest, without any such contractual limitations.

        On February 10, 2016, Mintz Levin distributed a draft of the merger agreement to Madrigal, its advisors and legal counsel, Stradling Yocca Carlson & Rauth, P.C., or Stradling.

        On February 12, 2016, Mintz Levin coordinated an organizational call with representatives from Synta, Madrigal, Stradling, Bay City Capital and Synta directors Gollust and Morenstein. Topics included the timeline for negotiating a definitive merger agreement and for Madrigal completing a private placement.

        On February 25, 2016, Synta engaged Roth Capital Partners, LLC, or Roth, to provide a fairness opinion.

        On February 29, 2016, Stradling provided Mintz Levin with a mark-up of the merger agreement.

        On March 1, 2016, Synta announced a second reduction in workforce, down to 10 full time employees.

        Throughout March, representatives from Synta and Madrigal and their advisors continued to perform due diligence on each other.

        On March 2, 2016, Mintz Levin provided Stradling with a high-level issues list based on Stradling's mark-up of the merger agreement.

        On March 10, 2016, Stradling distributed to Mintz Levin a draft of the private placement term sheet between Madrigal and its lead third-party investor.

        On March 16, 2016, Mintz Levin conducted a conference call with the legal counsel for Madrigal's third-party investor, Latham & Watkins LLP, or L&W.

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        On March 19, 2016, L&W and Stradling sent a superseding mark-up of the merger agreement to Mintz Levin, combining their comments but not addressing the Mintz Levin high-level issues list provided on March 2, 2016.

        On March 24, 2016, Chairman Gollust and a representative from Madrigal's third-party investor had an in-person meeting to discuss valuation, the minimum cash closing condition and the post-closing stock ownership split.

        On March 28, 2016, the representative from Madrigal's third-party investor informed Chairman Gollust that such investor was no longer interested in investing in Madrigal largely given the third-party's desire that Madrigal not become a publicly-listed company.

        As a result of this development, on March 30, 2016, Chairman Gollust, Dr. Friedman and Fred Craves, Ph.D. of Bay City Capital had several conversations sharpening Madrigal's cash needs to continue its clinical program during the pendency of a merger. The parties agreed that $9 million in funding would be sufficient versus the previously discussed $15 million. The parties also discussed the post-closing stock ownership split. Dr. Friedman, Dr. Taub, Bay City Capital and Fred Craves, Ph.D. agreed to irrevocably commit to invest $9 million to provide such bridge financing in the form of promissory notes that will convert upon the closing of the merger, and that the post-closing stock ownership split will be 36%/64%, providing Synta stockholders a higher post-closing ownership than previous proposals.

        On April 1, 2016, Mintz Levin distributed a revised merger agreement to the working group reflecting the foregoing and resolving most of issues in the high-level issues list dated March 2, 2016. Between April 1 and April 7, additional revised drafts of the merger agreement and ancillary agreements were circulated. On April 5, Mintz Levin coordinated an all-hands organizational call to review the "Checklist from here until Announcement". Finally, on April 8, 2016, a revised version of the merger agreement was circulated which resolved the open substantive points.

        On April 11, 2016, the Synta board of directors held an in-person meeting at the offices of CAM Capital in New York City for the purpose of reviewing and deliberating about the final terms of the merger agreement, including considering the fairness analysis of Roth with respect to the merger consideration and receiving an update about timing and open items. Participants included all directors (except Dr. Friedman) and representatives from Synta management, MTS, Mintz Levin and Roth.

        A detailed recap of the recent merger negotiations was provided. Among the key topics/events that were re-traced in detail and discussed by the board were:

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        The Mintz Levin representative provided a detailed review of the material terms of the merger agreement and ancillary agreements. During this review, several areas where Synta was successful in negotiating concessions or better outcomes than were originally advanced by Madrigal (including with respect to termination provisions and fees, Madrigal Material Adverse Effect definition and deal structuring provisions that increased deal certainty from Synta's perspective) were discussed, as well as other negotiated points. In particular, the post-signing passive market check provisions were reviewed, enabling Synta to negotiate and accept an unsolicited superior proposal and to terminate, on fiduciary grounds, the merger agreement with the payment of a termination fee. During this presentation, director questions were asked and addressed, including a detailed discussion about the minimum cash closing requirement and Synta's comfort level of satisfying that condition under various scenarios.

        Synta's General Counsel provided the final due diligence report on Madrigal, noting no issues outstanding.

        Representatives from Roth provided a detailed fairness presentation, during which directors' questions were asked and answered. It was noted that the delivery of the actual fairness opinion would occur at the time the board is ready to approve the definitive merger agreement, and that the materials presented on April 11, 2016 would be subject to confirmation at that time.

        The Mintz Levin representative provided a review of the board's fiduciary duties and other legal aspects. During this review, among other topics, two key matters were focused on:

The board expressed consensus and satisfaction that a full and complete process had been run and that the appropriate corporate governance steps had been taken. The board reiterated its view that the proposed transaction was the best opportunity for maximizing stockholder value, noting the objective merits of both (i) the process run and (ii) the ultimate selection of Madrigal based on scientific, clinical, market and probability-of-success grounds, and (iii) the deal terms. Further, it reiterated that having Dr. Friedman as the Chief Executive Officer of the combined entity is a significant positive benefit for stockholder value maximization, given Dr. Friedman's track record of success. In this connection, the board reiterated its view that the substantive benefits far outweighed the added complexity of potentially having to counteract any negative perception due to the related party aspects of the transaction. With respect to MTS, the board reiterated it was satisfied with how this matter was handled.

        Open issues with the transaction related mostly to the private placement, i.e, receiving definitive executed private placement documents showing an irrevocable investor commitment for $9 million, and confirming the exact amount of the first tranche and timing.

        On April 13, 2016, the Synta board of directors held a telephonic meeting at 4 p.m. (ET) for the purpose of approving the merger agreement. Attendees included all directors (except Dr. Friedman) and representatives from Synta management, MTS, Mintz Levin and Roth. After it was confirmed that there were no material changes to the merger agreement or to its presentation materials, Roth orally presented its fairness opinion, which was confirmed by delivery of a written opinion dated April 13,

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2016, that, as of that date, and based upon the assumptions, qualifications and limitations set forth in its opinion, the consideration to be paid in the merger was fair, from a financial point of view, to Synta.

        After discussion, the Synta board of directors participating in the meeting then unanimously (i) determined that the merger was advisable and in the best interests of Synta and its stockholders, (ii) approved the merger agreement, the merger and the other transactions contemplated by the merger agreement and deemed the merger agreement advisable, and (iii) approved and determined to recommend the approval of the issuance of the shares of Synta common stock in connection with the merger.

        Management was directed to sign the merger agreement. In the evening of April 13, 2016, the merger agreement was signed and Dr. Friedman concurrently resigned from the board of directors of Synta.

        On April 14, 2016 at 7 a.m. (ET) Synta and Madrigal issued a joint press release publicly announcing the signing of the definitive merger agreement.

Reasons for the Merger

        Following the merger, the combined company will focus on the development of novel small-molecule drugs addressing major unmet needs in cardiovascular-metabolic diseases and non-alcoholic steatohepatitis, or NASH.

        Synta's board of directors considered the following factors in reaching its conclusion to approve the merger and to recommend that the Synta stockholders approve the issuance of shares of Synta common stock in the merger, all of which Synta's board of directors viewed as supporting its decision to approve the business combination with Madrigal:

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        Synta's board of directors also reviewed the recent financial condition, results of operations and financial condition of Synta, including:

        Synta's board of directors also reviewed the terms of the merger and associated transactions, including:

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        In the course of its deliberations, Synta's board of directors also considered a variety of risks and other countervailing factors related to entering into the merger, including:

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        The foregoing information and factors considered by the Synta board are not intended to be exhaustive but are believed to include all of the material factors considered by the board. In view of the wide variety of factors considered in connection with its evaluation of the merger and the complexity of these matters, the board did not find it useful, and did not attempt, to quantify, rank or otherwise assign relative weights to these factors. In considering the factors described above, individual members of the board may have given different weight to different factors. The Synta board conducted an overall analysis of the factors described above, including thorough discussions with, and questioning of, the Synta management team and the legal and financial advisors of Synta, and considered the factors overall to be favorable to, and to support, its determination.

Opinion of Roth Capital Partners, LLC as Synta's Financial Advisor

        The Synta board of directors retained Roth Capital Partners, LLC on February 25, 2016 to render an opinion as to the fairness to Synta, from a financial point of view, of the merger consideration to be paid by Synta to the holders of shares of Madrigal common stock, or consideration, in the merger pursuant to the Merger Agreement.

        On April 13, 2016, Roth rendered its oral opinion to the board of directors of Synta (which was subsequently confirmed in writing by delivery of Roth's written opinion dated the same date) to the effect that, based upon and subject to the assumptions, factors, qualifications and limitations set forth in the written opinion described herein, as of April 13, 2016, the consideration to be paid by Synta in the merger was fair, from a financial point of view, to Synta.

        Roth's opinion was prepared solely for the information of the board of directors of Synta and only addressed the fairness, from a financial point of view, to Synta of the consideration to be paid by Synta in the merger. Roth was not requested to opine as to, and Roth's opinion does not address, the relative merits of the merger or any alternatives to the merger, Synta's underlying decision to proceed with or effect the merger, or any other aspect of the merger. Roth's opinion does not address the fairness of the merger to the holders of any class of securities, creditors or other constituencies of Synta and is not a valuation of Synta or Madrigal or their respective assets or any class of their securities. Roth did not express an opinion about the fairness of the amount or nature of any compensation payable or to be paid to any of the officers, directors or employees, of Madrigal, whether or not relative to the merger.

        The summary of Roth's opinion in this proxy statement is qualified in its entirety by reference to the full text of its written opinion, which is included as Annex B to this proxy statement and sets forth the procedures followed, assumptions made, qualifications and limitations on the review undertaken and other matters considered by Roth in preparing its opinion. Roth's opinion was prepared solely for the information of the board of directors of Synta for its use in connection with its consideration of the merger. Neither Roth's written opinion nor the summary of its opinion and the related analyses set forth in this proxy statement are intended to be, and they do not constitute, advice or a recommendation to any stockholder as to how such stockholder should act or vote with respect to any matter relating to the merger or any other matter.

        The full text of Roth's opinion, which sets forth the assumptions made, general procedures followed, factors considered and limitations on the review undertaken by Roth in rendering its opinion is attached as Annex B and is incorporated herein by reference. Synta urges you to read the opinion in its entirety. The summary of the opinion of Roth set forth below is qualified in its entirety by reference to the full text of the opinion. Roth's opinion, based upon and subject to the procedures followed, assumptions made, qualifications and limitations on the review undertaken and the other factors Roth deemed relevant, is that the consideration to be paid by Synta in the merger is fair, from a financial point of view, to Synta.

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        The terms of the merger, the consideration to be paid in the merger, and the related transactions were determined through arm's length negotiations between Synta and Madrigal and were approved unanimously by Synta's board of directors. Roth did not determine the consideration to be paid by Synta in connection with the merger.

        In connection with rendering the opinion described above and performing its related financial analyses, Roth, among other things:

        The following is a summary of the material financial analyses performed by Roth in connection with the preparation of its fairness opinion, which opinion was rendered orally to the board of directors of Synta (and subsequently confirmed in writing by delivery of Roth's written opinion dated the same date) on April 13, 2016. The preparation of analyses and a fairness opinion is a complex analytic process involving various determinations as to the most appropriate and relevant methods of financial analysis and the application of those methods to the particular circumstances and, therefore, such an opinion is not readily susceptible to summary description and this summary does not purport to be a complete description of the analyses performed by Roth or the delivery of Roth's opinion to the board of directors of Synta.

        This summary includes information presented in tabular format. In order to fully understand the financial analyses presented by Roth, the tables must be read together with the text of each analysis summary and considered as a whole. The tables alone do not constitute a complete summary of the financial analyses. Considering any portion of such analyses and of the factors considered, without considering all analyses and factors, could create a misleading or incomplete view of the process underlying Roth's opinion.

        In arriving at its opinion, Roth relied upon and assumed, without independent verification, the accuracy and completeness of all information that was publicly available or was furnished, or otherwise made available to Roth or discussed with or reviewed by or for Roth, and further assumed that the financial information provided to Roth had been prepared on a reasonable basis in accordance with industry practice, and that management of Synta was not aware of any information or facts that would make any information provided to Roth incomplete or misleading.

        With respect to the financial forecasts, estimates and other forward-looking information reviewed by Roth, Roth assumed that such information had been reasonably prepared based on assumptions reflecting the best currently available estimates and judgments of Synta' management as to the expected future combined results and financial condition of Synta and Madrigal after giving effect to the merger.

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Roth was not engaged to assess the achievability of any such financial forecasts, estimates or forward-looking information or the assumptions on which they were based, and Roth expressed no opinion as to such information or assumptions. In addition, Roth did not assume any responsibility for, and did not perform, any appraisals or valuation of any specific assets or liabilities (fixed, contingent or other) of Synta or Madrigal, nor was Roth furnished or provided with any such appraisals or valuations. Without limiting the generality of the foregoing, Roth was not engaged to, and did not undertake, any independent analysis of any pending or threatened litigation, regulatory action, possible unasserted claims or other contingent liabilities, to which Synta, Madrigal or any of their respective affiliates is a party or may be subject, and at the direction of Synta and with its consent, Roth's opinion made no assumption concerning, and did not consider, the possible assertion of claims, outcomes or damages arising out of any such matters.

        Roth relied upon and assumed that the representations and warranties of all parties set forth in the Merger Agreement and all related documents and instruments that are referred to therein are true and correct, that each party will fully and timely perform all of the covenants and agreements required to be performed by such party, that the merger will be consummated pursuant to the terms of the Merger Agreement, without amendment, and that all conditions to the consummation of the merger will be satisfied without waiver thereof. Roth further assumed that the Merger Agreement was in all material respects identical to the draft of the Merger Agreement provided to Roth. Finally, Roth also assumed that all of the necessary regulatory approvals and consents required for the merger, including the approval of the stockholders of Synta and Madrigal, will be obtained in a manner that will not adversely affect Synta or Madrigal or the contemplated benefits of the merger.

        In connection with its opinion, Roth assumed and relied upon, without independent verification, the accuracy and completeness of all of the financial, legal, regulatory, tax, accounting and other information provided to, discussed with or reviewed by it. Roth's opinion does not address any legal, regulatory, tax or accounting issues. Roth's fairness opinion was approved by its fairness committee prior to delivering it to Synta.

        Roth's opinion is necessarily based upon the information available to Roth and facts and circumstances as they exist and are subject to evaluation as of April 13, 2016, which is the date of the Roth opinion. Although events occurring after the date of the Roth opinion could materially affect the assumptions used in preparing the opinion, Roth does not have any obligation to update, revise or reaffirm its opinion and Roth expressly disclaims any responsibility to do so. Roth did not express any opinion as to the price at which shares of Synta's common stock may trade following announcement of the merger or at any future time.

        The consideration to be paid by Synta in the merger was determined through arm's length negotiations between Synta and Madrigal and was approved by the Synta and Madrigal boards of directors. Roth did not provide advice to Synta's board of directors during these negotiations, the decision to enter into the merger was solely that of Synta's board of directors. Roth's opinion and its presentation to Synta's board of directors was one of many factors taken into consideration by the Synta board of directors in deciding to approve, adopt and authorize the Merger Agreement. Consequently, the analyses as described herein should not be viewed as determinative of the opinion of Synta's board of directors with respect to the consideration to be paid by Synta in the merger or of whether Synta's board of directors would have been willing to agree to different consideration. The following is a brief summary of each of the material analyses performed by Roth in connection with its opinion letter dated April 13, 2016.

        In furnishing its opinion, Roth did not attempt to combine the analyses described herein into one composite valuation range, nor did Roth assign any quantitative weight to any of the analyses or the other factors considered. Furthermore, in arriving at its opinion, Roth did not attribute any particular weight to any analysis or factor considered by it, but rather made qualitative judgments as to the

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significance and relevance of each analysis and factor in light of one another. Accordingly, Roth has stated that it believes that its analyses must be considered as a whole and that considering any portion of its analyses, without considering all of the analyses, could create a misleading or incomplete view of the process underlying its opinion or the conclusions to be drawn therefrom.

        In conducting the analysis as to the fairness to Synta, from a financial point of view, of the consideration to be paid by Synta pursuant to the terms of the Merger Agreement, Roth conducted a stand-alone valuation of Synta. Roth then conducted a valuation of Synta and Madrigal as a pro-forma combined entity, against which Roth compared the pro-forma Synta ownership based on the Merger Agreement, with Synta's stand-alone valuation.

        The results of the application by Roth of each of the valuation methodologies utilized in connection with its fairness opinion is summarized below.

Stand-Alone Valuation

        Roth conducted an analysis of the value of Synta on a stand-alone basis. As a result of the recent termination of the GALAXY-2 trial Synta's Phase 3 clinical study of ganetespib, Roth did not perform a valuation using traditional valuation analyses, such as a discounted cash flow analysis or trading comparables for Synta as a stand-alone entity. Based on the last reported sale price of Synta common stock on April 12, 2016, and 137,806,441 shares of Synta common stock outstanding as of April 12, 2016, Roth determined that Synta's stand-alone public equity value was $31.7 million and that its stand-alone implied enterprise value was $(0.3) million, after subtracting Synta's net cash of approximately $32 million.

Consideration to be paid in the Merger

        Based upon the closing price per share of Synta common stock on April 12, 2016 of $0.2308 and the issuance in the merger of 253,878,117 shares of Synta common stock, Roth observed that Synta was paying approximately $58.6 million to acquire Madrigal.

Valuation of Combined Company

        Roth evaluated the value of the combined company after giving effect to the merger, or NewCo, using the following valuation methodologies:

        Utilizing the various valuation methodologies listed above, Roth estimated a valuation of NewCo utilizing the Precedent M&A Transactions of $470.0 million to $503.0 million; Comparable Licensing Transactions of $457.9 million to $553.5 million; Discounted Cash Flow Analysis of $177.2 million to $226.0 million; IPO Comparables of $181.9 million to 188.6 million; Implied Valuation from the Concurrent Company Private Placement of $89.0 million to $93.3 million; Precedent Reverse Merger Transactions of $68.5 million to $138.0 million; Publicly Traded Comparable Company Analysis: Hepatology of $241.5 million to $265.1 million and Publicly Traded Comparable Company Analysis:

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NASH of $68.3 million to $192.2 million. Roth then determined the average of these eight methodologies which ranged from $219.3 million to $270.1 million.

        The results of these analyses are summarized as follows:

 
  Implied Enterprise
Value
 
Methodology
  Low   High  

Precedent M&A Transactions

  $ 470.0   $ 503.0  

Licensing Comparables

  $ 457.9   $ 553.5  

Discounted Cash Flow Analysis

  $ 177.2   $ 226.0  

IPO Comparables

  $ 181.9   $ 188.6  

Concurrent Private Placement—Implied Valuation

  $ 89.0   $ 93.3  

Precedent Reverse Merger Transactions(1)

  $ 68.5   $ 138.0  

Comparable Company Analysis—Hepatology

  $ 241.5   $ 265.1  

Comparable Company Analysis—NASH

  $ 68.3   $ 193.2  

Average

  $ 219.3   $ 270.1  

Madrigal (64%)

  $ 140.3   $ 172.8  

Synta (36%)

  $ 78.9   $ 97.2  

Notes:

High and low ranges are based on mean and median values.

Valuations calculated at the agreed 36% Synta / 64% Madrigal split.

(1)
Enterprise value calculated assuming NewCo's pro-forma net cash of $41 million.

        Based on their valuation analysis, Roth determined that the enterprise value of NewCo ranged from $219 million to $270 million. Further, based on this analysis, Roth determined that:

Precedent M&A Transactions

        The precedent transaction analysis uses data based on the values acquirers have previously placed on comparable companies in a merger or acquisition to develop a measure of current value for Synta.

        Roth examined precedent transactions, from June 1, 2014 through April 13, 2016, involving clinical development companies that it viewed as similar to Synta, which included companies involved in the NASH and inflammatory disease spaces with available transaction values. These entities were selected on the basis of the nature of their businesses, their size and operating characteristics. The data available on these transactions, due in part to their size, is limited. Roth examined the data points set out in the table below for the selected precedent transactions.

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        Selected life sciences M&A transactions indicate a median and mean deal value of $470 million and $503 million, respectively.

Date
  Acquirer   Target   Deal
Value ($M)
 

4/2016

  Gilead   Nimbus Therapeutics   $ 1,200  

10/2015

  Roche   Adheron Therapeutics   $ 580  

9/2015

  Celsus Therapeutics   Akari Therapeutics   $ 150  

7/2015

  TiGenix   Coretherapix   $ 319  

5/2015

  Boehringer Ingelheim   Pharmaxis   $ 542  

1/2015

  Gilead   Phenex   $ 470  

6/2014

  Shire   Lumena Pharmaceuticals   $ 260  

     

Mean

 
$

503
 

      Median   $ 470  

Source: Evaluate Pharma

Note: Includes comparable M&A transactions from 2014-2016 YTD with available deal values.

Licensing Comparables

        Roth reviewed financial terms, to the extent publicly available, of licensing transactions for assets in the NASH and inflammatory spaces at comparable stages of development, from March 1, 2009 to April 13, 2016.

        Selected life sciences licensing deals had a median and mean deal value of $554 million and $458 million, respectively

Date
  Licensor   Licensee   Asset   Transaction
Value ($M)
 

3/2015

  Boehringer Ingelheim   Pharmaxis   PXS4728A   $ 591  

2/2013

  Medicines Co.   Alnylam Pharmaceuticals   ALN-PCS RNAi Therapeutic Program   $ 205  

10/2011

  Biogen Idec Inc.   Portola Pharmaceuticals   PRT062607   $ 554  

12/2010

  Servier   Xoma   XOMA 052   $ 555  

3/2009

  BMS   Nissan Chemical / Teijin Pharma   NTC-801   $ 385  

          Mean   $ 458  

          Median   $ 554  

Source: Evaluate Pharma

Note: Includes comparable licensing transactions from 2009 - 2016 YTD with available transaction values.

Discounted Cash Flow Analysis

        The discounted cash flow analysis is a "forward looking" methodology and is based on projected future cash flows to be generated by NewCo which are then discounted back to the present. This methodology has three primary components: (1) the present value of projected unlevered cash flows for a determined period; (2) the present value of the terminal value of cash flows based on the declining growth method (representing firm value beyond the time horizon on the projections); (3) the weighted average cost of capital, or WACC, used to discount such future cash flows and terminal value back to

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the present. In the discounted cash flow analysis, Roth used management's unlevered free cash flow projections. The future cash flows plus the terminal value of such cash flows are discounted by the WACC, to derive a present value.

        In conducting its discounted cash flow analysis for the purpose of determining the enterprise value of NewCo, Roth applied the projected unlevered free cash flow that NewCo is expected to generate during fiscal years 2016 to 2031 based upon financial projections prepared by Synta's management. Terminal values based on declining cash flow at a rate of 3% to 5% were applied to management's cash flow estimates in year 2031 to complete the basis for calculating the present value of future free cash flows. The future free cash flows are then discounted by the WACC, to derive a present value. In selecting an appropriate discount rate, Roth took into account NewCo's unlevered equity beta, NewCo's debt to equity ratio, NewCo's tax rate assumption, the risk free rate of 1.7% based on Bloomberg (April 8, 2016), the equity risk premium of 19% based on Duff & Phelps 2015 Valuation Handbook representing the long-term historical equity risk premium as of year-end 2014 of 7.0%, and a small stock premium of 11.98% based on Duff & Phelps 2015 Valuation Handbook representing the micro-cap premium for the CRSP bottom 10th decile of companies. Application of the foregoing principles resulted in a 24% WACC. Roth performed a sensitivity analysis using discount rates from 23.0% to 25.0% to arrive at a range of present values.

        Based on the foregoing, Roth computed an enterprise value range of $177 million to $226 million which compared favorably to the enterprise value implied by the consideration to be paid by NewCo in the merger, including the merger consideration. In evaluating the foregoing, it should be noted that the WACC does not take into consideration the specific firm risks such as bankruptcy. As a result, NewCo's true WACC may be higher when taking into consideration the risks of default and negative operating profit history of the business which would have the effect of reducing the enterprise value range. By conducting an analysis of a range of discount rates rather than relying one specific WACC, Roth is comfortable that the analysis is appropriate.

        A discounted cash flow analysis of Madrigal's estimates yields an implied enterprise value of NewCo of between $177M and $226M without attributing any value to Synta.

Madrigal Pharmaceuticals, Inc.

Discounted Cash Flow Analysis

($ in millions)
  2016   2017   2018   2019   2020   2021   2022   2023  

Madrigal Revenue Projections

  $   $   $   $ 10.5   $ 52.2   $ 75.1   $ 137.2   $ 218.0  

YoY Growth

                            398 %   44 %   83 %   59 %

Unlevered Free Cash Flow (Partial Yr Adj)

  $ (9 ) $ (20 ) $ (28 ) $ (14 ) $ 29   $ 21   $ 52   $ 82  

 

 
  2024   2025   2026   2027   2028   2029   2030   2031  

Madrigal Revenue Projections

  $ 315.6   $ 431.2   $ 472.0   $ 514.8   $ 528.2   $ 542.1   $ 556.6   $ 571.7  

YoY Growth

    45 %   37 %   9 %   9 %   3 %   3 %   3 %   3 %

Unlevered Free Cash Flow (Partial Yr Adj)

  $ 129   $ 186   $ 216   $ 238   $ 247   $ 256   $ 265   $ 289  

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Declining Growth Terminal Value Methodology   Declining Growth
Method
 
 
   
  PV of Terminal
Value Declining
Growth Method
 
 
   
  NPV+Terminal Value  
 
  NPV of Cash
Flows
(2016 - 2031)
 
Discount Rate
  3%   5%   7%   3%   5%   7%  

23.0%

  $ 173   $ 53   $ 50   $ 47   $ 226   $ 223   $ 221  

23.5%

  $ 165   $ 49   $ 46   $ 44   $ 214   $ 211   $ 209  

24.0%

  $ 157   $ 45   $ 43   $ 41   $ 202   $ 200   $ 198  

24.5%

  $ 150   $ 41   $ 39   $ 38   $ 191   $ 189   $ 187  

25.0%

  $ 142   $ 38   $ 37   $ 35   $ 181   $ 179   $ 177  

(1)
FY2016 - FY2031 figures are based on Madrigal's estimates

Comparable Hepatology IPOs

        Roth reviewed the implied total enterprise values at IPO of six companies which completed initial public offerings since 2012 and that were developing hepatology products at the time of their IPO. The implied total enterprise values at IPO are defined as the equity value of the company plus indebtedness, minus cash and cash equivalents at the time of the IPO. Roth also reviewed the IPO step-up multiple of comparable hepatology IPOs which compares the pre-money valuation of the latest private financing round, if available, with the post IPO equity value.

        Prior hepatology initial public offerings had a median and average enterprise value of $189 million and $182 million, respectively.

Pricing Date
  Company   Ticker   Offer
Price
  Amount
Raised
in IPO
($M)
  Pre-Money
Equity
Valuation
($M)
  IPO
Step-up
Multiple
($M)
  Post IPO
Market
Value
($M)
  Enterprise
Value
($M)
 

04/16/14

  Vital Therapies Inc   VTL   $ 12.00   $ 62.1     NA     NA   $ 253.4   $ 207.3  

03/12/14

  Galmed Pharmaceuticals Ltd   GLMD   $ 13.50   $ 44.1     NA     NA   $ 141.7   $ 141.6  

07/24/13

  Conatus Pharmaceuticals Inc   CNAT   $ 11.00   $ 66.0   $ 70.6     2.4x   $ 167.2   $ 165.7  

03/20/13

  Enanta Pharmaceuticals, Inc.   ENTA   $ 14.00   $ 64.4   $ 117.5     2.0x   $ 235.7   $ 190.2  

10/10/12

  Intercept Pharmaceuticals, Inc.   ICPT   $ 15.00   $ 86.3   $ 124.0     1.9x   $ 236.0   $ 200.0  

07/25/12

  Hyperion Therapeutics, Inc.   HPTX   $ 10.00   $ 57.5     NA     NA   $ 153.7   $ 186.9  

 

Mean

 
$

63.4
 
$

104.0
   
2.1x
 
$

198.0
 
$

181.9
 

  Median   $ 63.3   $ 117.5     2.0x   $ 201.5   $ 188.6  

Source: Capital IQ. Company Filings. Deal Logic. Venture Source

Concurrent Private Placement—Implied Valuation

        In the Madrigal private placement, investors will be investing $9.0 million into Madrigal, prior to the closing of the merger, based on a pre-money valuation of $40.0 million. At the time of the merger, Madrigal's post-money private valuation will be approximately $49.0 million.

        When Roth applies the step-up multiple from comparable hepatology IPO transactions to Madrigal's post-money private valuation of $49.0 million, Roth arrives at an implied public equity valuation range of $98.3 million to $102.6 million for Madrigal. This range is higher than the $58.6 million in value being paid by Synta.

        Adding Synta's equity value of $31.7 million results in an implied combined public equity value for Newco of between $130.0 million to $134.3 million for NewCo.

        After accounting for the net cash position of NewCo, Roth arrived at an enterprise valuation range of $89.0 million to $93.3 million.

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Concurrent Private Placement—Implied Valuation ($ in millions)

 
  Madrigal  

Equity Investment

  $ 9.0  

Implied Valuation(1)

  $ 40.0  

Implied Post-Money Valuation

  $ 49.0  

 

 
  Implied Equity
Value
 
 
  Low   High  

The Company(2)

  $ 98.3   $ 102.6  

Synta(3)

  $ 31.7   $ 31.7  

NewCo

  $ 130.0   $ 134.3  

(1)
Pre-money valuation provided by the Company's counsel

(2)
Low and high implied equity value based on median and mean comparable hepatology IPO step-up multiples of 2.0x and 2.1x, respectively

(3)
Market capitalization as of 4/12/2016

 

 
  Implied
Enterprise
Value
 
 
  Low   High  

NewCo

  $ 89.0   $ 93.3  

Precedent Reverse Merger Transactions

        Roth reviewed precedent reverse merger transactions in the healthcare space including targets with cash balances greater than $10 million in the surviving entity post transaction. The implied equity value was calculated based on the target equity value prior to the transaction and the implied valuation based on the retained target percentage ownership in the surviving entity. Roth also reviewed the mean and median target ownership percentage in the transactions.

        Selected life sciences reverse merger transactions including targets with cash balances greater than $10 million in the surviving entity had a median and average total equity value of $110 million and $179 million, respectively

        Based on this analysis, the implied enterprise value is between $69 million and $138 million, after accounting for the $41 million net cash position of NewCo.

        In comparable precedent reverse merger transactions, the target retains 23% of the surviving entity on average.

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        Implied Equity Value ($M)

Date(1) Target Company
  Private
Company
  Market
Cap
Target
($M)(2)
  Target
% Ownership
  Acquirer
% Ownership
  Target
Value
  Acquirer
Value
  Total
Equity
Value
 

12/2015 Restorgenex Corporation

  Diffusion Pharmaceuticals Inc.   $ 18.6     17.0 %   83.0 % $ 18.6   $ 90.9   $ 109.5  

3/2015 Ruthigen, Inc. 

  Pulmatrix, Inc.   $ 19.6     19.0 %   81.0 % $ 19.6   $ 83.5   $ 103.0  

3/2015 Targacept, Inc. 

  Catalyst Biosciences, Inc.   $ 12.6     42.0 %   58.0 % $ 12.6   $ 17.5   $ 30.1  

1/2015 Regado Biosciences, Inc. 

  Tobira Therapeutics, Inc.   $ 30.2     32.0 %   68.0 % $ 30.2   $ 64.3   $ 94.5  

7/2014 Transcept Pharmaceuticals, Inc. 

  Paratek Pharmaceuticals, Inc.   $ 37.1     10.4 %   89.6 % $ 37.1   $ 320.0   $ 357.2  

4/2014 Zalicus Inc. 

  EPIRUS Biopharmaceuticals, Inc.   $ 31.6     19.0 %   81.0 % $ 31.6   $ 134.7   $ 166.3  

4/2013 Tranzyme, Inc. 

  Ocera Therapeutics, Inc.   $ 11.9     27.4 %   72.6 % $ 11.9   $ 31.4   $ 43.3  

4/2012 Nabi Biopharmaceuticals Inc. 

  Biota Pharmaceuticals, Inc.   $ 78.5     17.0 %   83.0 % $ 78.5   $ 383.2   $ 461.7  

6/2011 Trimeris Inc

  Synageva BioPharma Corp.   $ 61.4     25.0 %   75.0 % $ 61.4   $ 184.1   $ 245.5  

  Mean           23.2 %   76.8 % $ 33.5   $ 145.5   $ 179.0  

  Median           19.0 %   81.0 % $ 30.2   $ 90.9   $ 109.5  

Source: Capital IQ and Company Filings

Note: Includes comparable reverse merger transactions from 2011-2016 YTD

(1)—Transaction announcement

(2)—Calculated as of week prior to announcement date

Comparable Companies Analysis

        Roth reviewed the total enterprise values of publicly traded companies with hepatology product candidates in development as well as selected publicly traded companies developing products for NASH. The comparable companies' analysis uses data from comparable guideline companies to develop a measure of current value for NewCo. The theory underlying the comparable companies' valuation is that companies in the same industry with similar operating characteristics should have certain valuation benchmarks in common. The goal of the analysis is to develop a premise for relative value, which when coupled with other valuation approaches, presents a foundation for determining a range of firm value.

Comparable Company Analysis—Hepatology

        Selected hepatology trading comparables had a median and mean enterprise value of $242 million and $265 million, respectively.

Company
  Ticker   4/12/2016
Price
  52 Week
High
  52 Week
Low
  Market
Cap ($M)
  Enterprise
Value ($M)
 

Achillion Pharmaceuticals, Inc. 

  ACHN   $ 8.24   $ 11.03   $ 5.63   $ 1,109.5   $ 650.6  

Enanta Pharmaceuticals, Inc. 

  ENTA   $ 31.60   $ 50.65   $ 21.52   $ 585.5   $ 406.3  

Regulus Therapeutics Inc. 

  RGLS   $ 7.99   $ 18.29   $ 5.34   $ 413.7   $ 299.7  

Vital Therapies, Inc. 

  VTL   $ 8.80   $ 29.37   $ 3.04   $ 266.6   $ 183.2  

Conatus Pharmaceuticals Inc.(1)

  CNAT   $ 2.98   $ 6.81   $ 1.54   $ 61.8   $ 26.3  

Ocera Therapeutics, Inc. 

  OCRX   $ 2.86   $ 4.68   $ 2.03   $ 58.2   $ 24.3  

Mean

                        $ 415.9   $ 265.1  

Median

                        $ 340.2   $ 241.5  

Note: Data as of 4/12/16

(1)—Included in NASH Comparables

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Comparable Company Analysis—NASH

        Selected NASH trading comparables had a median and mean enterprise value of $68 million and $193 million, respectively.

Company
  Ticker   4/12/2016
Price
  52 Week
High
  52 Week
Low
  Market
Cap ($M)
  Enterprise
Value ($M)
 

Intercept Pharmaceuticals, Inc.(1)

  ICPT   $ 145.57   $ 313.98   $ 93.71   $ 3,576.0   $ 2,947.9  

Genfit SA

  GNFT   $ 28.06   $ 49.75   $ 23.87   $ 739.6   $ 680.5  

Regulus Therapeutics Inc. 

  RGLS   $ 7.99   $ 18.29   $ 5.34   $ 413.7   $ 299.7  

Tobira Therapeutics, Inc. 

  TBRA   $ 7.22   $ 22.76   $ 6.37   $ 135.1   $ 87.8  

Galmed Pharmaceuticals Ltd. 

  GLMD   $ 6.36   $ 11.85   $ 3.76   $ 71.8   $ 48.8  

Conatus Pharmaceuticals Inc. 

  CNAT   $ 2.98   $ 6.81   $ 1.54   $ 61.8   $ 26.3  

Galectin Therapeutics, Inc. 

  GALT   $ 1.46   $ 3.73   $ 1.08   $ 41.8   $ 16.0  

Mean

                        $ 244.0   $ 193.2  

Median

                        $ 103.5   $ 68.3  

Note: Data as of 4/12/2016

(1)—Excluded from mean & median calculation.

        As discussed above, Roth performed a variety of financial and comparative analyses for the purpose of rendering its opinion. While the preceding summary describes several analyses and examinations that Roth deems material to its evaluation and opinion, they are not a comprehensive description of all analyses and examinations actually conducted by Roth.

General

        Roth is a nationally recognized investment banking firm that provides financial advisory services and is continually engaged in the valuation of businesses and their securities in connection with mergers and acquisitions, negotiated underwritings, secondary distributions of listed and unlisted securities, private placements and valuations for estate, corporate and other purposes. The Synta board of directors retained Roth to render an opinion as to the fairness to Synta, from a financial point of view, of the consideration to be paid in the merger by Synta based upon the foregoing qualifications, experience and expertise.

        Synta paid Roth a fee of $200,000 for rendering its fairness opinion delivered in connection with the merger. The $200,000 opinion fee was not contingent in whole or in part on the success of the merger, or on the results of Roth's evaluation and analysis or upon the conclusions reached in Roth's opinion. In addition, Synta agreed to reimburse Roth up to $25,000 for its reasonable, documented, out-of-pocket expenses, including reasonable fees and disbursements of its counsel. Synta has also agreed to indemnify Roth against certain liabilities and other items that may arise out of the Synta's engagement of Roth. Synta's board of directors did not limit Roth in any way in the investigations it made or the procedures it followed in rendering its opinion.

        Roth in the past has provided and may in the future provide investment banking and other financial services to Synta and its affiliates for which Roth and its affiliates have received or may receive compensation. In March 2015, Roth acted as a co-manager of a public offering by Synta of shares of its common stock and received substantial fees in connection therewith. Roth is a full service securities firm engaged in securities trading and brokerage activities, as well as providing investment banking and other financial services. In the ordinary course of business, Roth and its affiliates may actively trade securities of Synta for its own account or the accounts of its customers and, accordingly, may at any time hold a long or short position in such securities.

        Consistent with applicable legal and regulatory requirements, Roth has adopted policies and procedures to establish and maintain the independence of its research departments and personnel. As a

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result, Roth's research analysts may hold views, make statements or investment recommendations and/or publish research reports with respect to Synta, Madrigal and/or the merger that differ from the views of its investment banking personnel.

MTS Health Partners Fees

        The following provides a summary of the transaction fees payable to MTS upon the closing of this transaction pursuant to its separate engagement letters with Synta and Madrigal for financial advisory services. MTS has received no prior fees from any other engagements from (i) Dr. Friedman or entities affiliated with him, or (ii) Bay City Capital (Madrigal's major stockholder); its partner, Fred Craves, Ph.D.; or any Bay City portfolio companies.

        Pursuant to its engagement letter with Synta, it was contemplated upfront that any transaction fee payable to MTS would be reduced if Synta completed a transaction with Madrigal, in recognition of another team at MTS previously engaged to provide advisory services to Madrigal and the cost of Synta hiring a separate, independent investment banking firm to provide a fairness opinion with respect to such transaction. Specifically, for a non-Madrigal party, MTS would have received a transaction fee upon closing of $1,750,000, of which $500,000 would be payable in shares of Synta common stock to be issued at the closing, such number of shares to be determined based on the per share market value of such shares immediately preceding the closing date. This transaction fee would have encompassed a $350,000 opinion fee to MTS, fully creditable against the transaction fee payable at any closing. However, in a transaction involving Madrigal, the transaction fee is $1,000,000, of which $250,000 will be payable in Synta shares of common stock to be issued at the closing. MTS also received a nonrefundable retainer payment of $100,000, which is fully creditable against the transaction fee, and customary expense reimbursement.

        Pursuant to its engagement letter with Madrigal, MTS is entitled to a transaction fee of $1,250,000, with up to a maximum of $500,000 payable in shares of Synta common stock to be issued at the closing (the number determined as described above), and the remainder, a minimum of $750,000, in cash. MTS also received a nonrefundable retainer payment of $50,000 and customary expense reimbursement.

Interests of the Synta Directors and Executive Officers in the Merger

General

        In considering the recommendation of the Synta board of directors with respect to the approval of the Merger Agreement, the merger and issuing shares of Synta common stock as contemplated by the Merger Agreement, and the other matters to be acted upon by the Synta stockholders at the Annual Meeting, the Synta stockholders should be aware that certain members of the board of directors and executive officers of Synta have interests in the merger that may be different from, or in addition to, the interests of the Synta stockholders. These interests relate to or arise from, among other things:

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        The board of directors of Synta was aware of these potential conflicts of interest and considered them, among other matters, in reaching their respective decisions to approve the Merger Agreement and the merger, and to recommend, as applicable, that the Synta stockholders approve the proposals to be presented to the Synta stockholders for consideration at the Annual Meeting as contemplated by this proxy statement.

Synta Director Paul A. Friedman's Relationship with Madrigal and Combined Company

        Paul A. Friedman, M.D. was a director of Synta from March 2014 until his resignation on April 13, 2016 concurrent with the announcement of the merger with Madrigal. As described below, Dr. Friedman has personal interests both in Madrigal and the combined company. These interests were fully disclosed to and known by the Synta board of directors and corporate governance measures were taken to address them, including Dr. Friedman's exclusion from Synta board of director proceedings with respect to Madrigal, as described more fully in "The Merger—Background of the Merger." These interests are:

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        The foregoing does not include options to purchase Synta common stock that Dr. Friedman currently holds as a result of his prior service as a director of Synta. Those options are all significantly out-of the-money (having exercise prices ranging from $2.20 to $6.15) and expire the 90th day (which is July 12, 2016) after his resignation from the Synta board of directors, unless exercised before such date. For more information, see "Principal Stockholders of Combined Company."

Golden Parachute Compensation

Overview

        This section sets forth the information required by Item 402(t) of Regulation S-K regarding the compensation for each of Synta's named executive officers that is based on or otherwise relates to the merger. This compensation is referred to as "golden parachute" compensation by the applicable Securities and Exchange Commission, or SEC, disclosure rules, and in this section Synta uses such term to describe the merger-related compensation payable to Synta's named executive officers.

Severance and Change of Control Agreements with Synta's Named Executive Officers

Severance and Change of Control Agreement with Chen Schor

        Pursuant to the terms of the severance and change of control agreement entered into with Synta's President and Chief Executive Officer, Chen Schor, in the event that within one year following a "change of control" (as defined in the severance and change of control agreement and set forth below) the officer's employment is terminated other than for "cause" or the officer terminates his employment for "good reason" (as such terms are defined in the severance and change of control agreement and set forth below), Mr. Schor is entitled to receive the following:

Severance and Change of Control Agreements with Marc R. Schneebaum and Wendy E. Rieder, Esq.

        Pursuant to the terms of the severance and change of control agreements entered into with Synta's Senior Vice Presidents, Marc R. Schneebaum and Wendy E. Rieder, Esq., in the event that within one year following a "change of control" the officer's employment is terminated other than for "cause" or the officer terminates his or her employment for "good reason," Mr. Schneebaum and Ms. Rieder are entitled to receive the following:

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Defined Terms in Severance and Change of Control Agreements

        As defined in the severance and change of control agreements:

        "Cause" includes, but is not limited to: (i) dishonesty with respect to us or any affiliate, parent or subsidiary of ours; (ii) insubordination; substantial malfeasance or nonfeasance of duty; (iii) unauthorized disclosure of confidential information; (iv) breach of any material provision of any employment, consulting, advisory, non-disclosure, invention assignment, non-competition, or similar agreement between us and the executive officer; or (v) conduct substantially prejudicial to our business or of any affiliate, parent or subsidiary of ours. Synta's board of directors has sole discretion to determine the existence of cause, and its determination will be conclusive on Synta and the executive officer. Cause is not limited to events which have occurred prior to the termination of the executive officer's service, nor is it necessary that the finding of cause occur prior to such termination. If Synta's board of directors determines, subsequent to the executive officer's termination of service, that either prior or subsequent to the termination the executive officer engaged in conduct which would constitute cause, then the executive officer will have no right to any benefit or compensation under the severance and change of control agreement.

        A "change of control" means the occurrence of any of the following events:

        "Good reason" means: (i) the executive officer, as a condition of remaining an employee of Synta's, is required to change the principal location where he or she renders services to Synta to a location more than 50 miles from his or her then-current location of employment; (ii) there occurs a material adverse change in the executive officer's duties, authority or responsibilities which causes his or her position with Synta to become of significantly less responsibility or authority than his or her position was on the date the severance and change of control agreement was executed; or (iii) there occurs a material reduction in the executive officer's base salary.

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Change of Control Arrangements Under our 2015 Stock Plan

        Under Synta's 2015 Stock Plan, in the event of a "change of control" (as defined above), which would include the merger, all outstanding options will become immediately exercisable in full and all rights of repurchase with respect to outstanding stock grants will terminate if on or prior to the date that is six months after the date of the change of control event (i) a participant's service with Synta' or Synta's succeeding corporation is terminated by Synta or the succeeding corporation without cause; (ii) a participant terminates his or her service with Synta as a result of being required to change the principal location where he or she renders services to a location more than 50 miles from his or her location of service immediately prior to the change of control event; or (iii) the participant terminates his or her service after there occurs a material adverse change in a participant's duties, authority or responsibilities which cause such participant's position with Synta to become of significantly less responsibility or authority than such participant's position was immediately prior to the change of control. Synta's 2006 Stock Plan, which was terminated in June 2015, contained similar provisions. Synta's 2001 Stock Plan, which was terminated in March 2006 and under which all outstanding equity awards granted thereunder have fully vested, contained similar provisions. Synta's 2006 Stock Plan also allows the board of directors to make appropriate adjustments for other stock-based awards. The term "change of control" under Synta's 2015 Stock Plan and 2006 Stock Plan has the same definition as it does under Synta's severance and change of control agreements.

Restricted Stock Units

        In December 2015, Synta's board of directors approved grants of restricted stock units to Chen Schor, Marc R. Schneebaum and Wendy Rieder that entitle such person to 1,500,000, 900,000 and 900,000 shares of common stock, respectively, upon the occurrence of a "transaction" (as defined below), which would include the merger. As of May 2, 2016, the common stock underlying the restricted stock units issued to Chen Schor, Marc R. Schneebaum and Wendy Rieder were worth $615,000, $369,000 and $369,000, respectively, based on a price per share of $0.41, the closing price of Synta's shares on May 2, 2016. For the purposes of the restricted stock unit agreements, "transaction" means, whether effected in one transaction or a series of related transactions, (a) any merger, consolidation, reorganization, recapitalization or restructuring, formation of a joint venture, partnership or other business combination pursuant to which the business of Synta or a substantial portion thereof is acquired by or combined with that of another person or entity or group of persons or entities (such person, entity or group, a "counterparty"); (b) any acquisition, directly or indirectly, by a counterparty of a majority of the capital stock of Synta, by way of purchase or any other means; (c) any acquisition, directly or indirectly, by a counterparty of at least 25% of the assets of Synta (determined either on the basis of fair market value or book value); (d) any acquisition, directly or indirectly, by Synta of a majority of the capital stock of a counterparty or any of its subsidiaries, by way of purchase or any other means; or (e) any acquisition, directly or indirectly, by Synta of a substantial portion of the assets of a counterparty and its subsidiaries (determined either on the basis of fair market value or book value) for consideration in excess of $20 million.

Aggregate Amounts of Potential Compensation

        The table below summarizes potential golden parachute compensation that each named executive officer could be entitled to receive from Synta if the merger is completed and if the named executive officer thereafter incurs a termination of employment under certain circumstances, as discussed below. It is currently expected that neither Chen Schor nor Wendy E. Rieder will continue to be employed by Synta following the closing of the merger and, accordingly, both will be entitled to receive the severance and benefits described above and below. Please note that the amounts indicated below are estimates based on multiple assumptions that may or may not actually occur, including assumptions

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described herein. Accordingly, the actual amounts, if any, to be received by such named executive officer may differ in material respects from the amounts set forth below.

        For purposes of calculating such potential golden parachute compensation, Synta has assumed that the merger had occurred on May 2, 2016, including with respect to calculating the portion of equity awards subject to accelerated vesting, and have further assumed that the named executive officers will incur a termination of employment on such date that would entitle them to the benefits set forth in the table below, even though it is anticipated that Marc R. Schneebaum will continue to serve as the Chief Financial Officer of the combined company following the merger.

 
  Golden Parachute Compensation  
 
  Cash(1)   Equity(2)   COBRA
Benefits(3)
  Total  

Chen Schor

  $ 867,000   $ 738,000   $ 40,914   $ 1,645,914  

Marc R. Schneebaum

  $ 413,667   $ 399,750   $ 19,614   $ 833,031  

Wendy E. Rieder, Esq. 

  $ 346,800   $ 369,000   $ 23,726   $ 739,526  

(1)
Amounts in this column represent the lump sum cash severance payment to be paid to each executive upon a termination of employment without "Cause" or a termination for "Good Reason" (as defined above), subject to the execution and non-revocation of a general release of claims in favor of Synta. Mr. Schor would receive 18 months base salary continuation and his prorated then-current target annual bonus. Mr. Schneebaum and Ms. Rieder each would receive 12 months base salary continuation and his or her prorated then-current target annual bonus.

(2)
These amounts reflect the aggregate amount attributable to the accelerated vesting of all outstanding restricted stock held by the named executive officers and the vesting of the restricted stock units described above under "—Restricted Stock Units." Upon termination related to change in control, there is full acceleration (100%) on the vesting of restricted stock for each of Mr. Schor and Mr. Schneebaum. Ms. Rieder does not hold any unvested shares of restricted stock. Messrs. Schor and Schneebaum and Ms. Rieder hold stock options with an exercise price per share above $0.41, the closing price of Synta's common stock on The NASDAQ Global Market on May 2, 2016, so such stock options are disregarded for this purpose. For restricted stock, the amounts in this column consider the value of each share of restricted stock to be $0.41, the closing price of the closing price of Synta's common stock on The NASDAQ Global Market on May 2, 2016.

(3)
The amounts in this column are calculated based on (a) the duration of the respective continuation periods, and (b) the monthly premiums that Synta pays for the medical, dental and life insurance coverage received by the named executive officer as of May 2, 2016.

        Management Following the Merger.    As described elsewhere in this proxy statement, including in "Management Following the Merger," certain of Synta's directors and executive officers are expected to become directors and executive officers of the combined company upon the closing of the merger.

        Indemnification and Insurance.    For a description of the indemnification rights afforded to Synta's directors and officers under the Merger Agreement, see "The Merger Agreement—Indemnification of Officers and Directors."

Limitations of Liability and Indemnification of the Synta and Madrigal Officers and Directors

        Pursuant to the Merger Agreement, upon the completion of the merger, Synta and Saffron Merger Sub, Inc., or Saffron Merger Sub, agreed that all rights to indemnification, exculpation or advancement of expenses now existing in favor of, and all limitations on the personal liability of each present and former director, officer, employee, fiduciary or agent of Synta or Madrigal as provided for in their

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respective organizational documents in effect as of the date of the Merger Agreement, will continue to be honored and in full force and effect for a period of six years after the closing of the merger.

        The certificate of incorporation and by-laws of the surviving corporation will contain provisions with respect to indemnification, exculpation from liability and advancement of expenses that are at least as favorable as those currently in Madrigal's organizational documents, and during such six year period following the closing of the merger, Synta will not amend, repeal or otherwise modify such provisions in any manner that would materially and adversely affect the rights of individuals who at any time prior to the effective time was a director, officer, employee, fiduciary or agent of Madrigal in respect of actions or omissions occurring at or prior to the closing of the merger.

        The Merger Agreement also provides that Madrigal will purchase a six-year "tail" policy under its existing directors' and officers' liability insurance policy, with an effective date as of the closing of the merger.

Stock Options

        Synta stock options and other equity awards that are oustanding immediately prior to the effective time of the merger will remain outstanding and be unaffected by the merger, provided that there will be an adjustment to the exercise price and the number of shares underlying these options and equity awards to account for reverse stock split.

Form of the Merger

        The Merger Agreement provides that at the effective time, Saffron Merger Sub will be merged with and into Madrigal. Upon the completion of the merger, Madrigal will continue as the surviving corporation and will be a wholly-owned subsidiary of Synta.

        After completion of the merger, Synta will be renamed "Madrigal Pharmaceuticals, Inc." and expects to trade on The NASDAQ Global Market or The NASDAQ Capital Market under the symbol "MDGL."

Merger Consideration and Adjustment

        At the effective time of the merger, each share of Madrigal common stock outstanding immediately prior to the effective time of the merger will automatically be converted into the right to receive 5.5740 shares of Synta common stock, subject to adjustment to account for the reverse stock split to be implemented prior to the closing of the merger.

        The Merger Agreement provides that, promptly after the effective time of the merger, Synta will mail to each holder of record of Madrigal capital stock a letter of transmittal and instructions for surrendering the record holder's stock certificates in exchange for the shares of Synta common stock. Upon proper surrender of Madrigal stock certificates together with a properly completed and duly executed letter of transmittal in accordance with Synta's instructions, the holder of such Madrigal stock certificates will be entitled to receive shares representing the number of whole shares of Synta common stock issuable to such holder pursuant to the merger and cash in lieu of any fractional share of Synta common stock issuable to such holder. The surrendered certificates representing Madrigal common stock will be cancelled.

        After the effective time of the merger, each certificate representing shares of Madrigal common stock that has not been surrendered will represent only the right to receive shares of Synta common stock issuable pursuant to the merger and cash in lieu of any fractional share of Synta common stock to which the holder of any such certificate is entitled. No interest will be paid or accrued on any cash in lieu of fractional shares payable to holders of Madrigal stock certificates.

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        Any holder or former holder of Madrigal common stock may be subject to withholding under the Code, or under another provision of state, local or foreign tax law. To the extent such amounts are withheld and paid to the appropriate governmental entity, they will be treated as having been paid to the person to whom such amounts would otherwise have been paid.

        The Merger Agreement does not include a price-based termination right, so there will be no adjustment to the total number of shares of Synta common stock that Madrigal stockholders will be entitled to receive for changes in the market price of Synta common stock. Accordingly, the market value of the shares of Synta common stock issued pursuant to the merger will depend on the market value of the shares of Synta common stock at the time the merger closes, and could vary significantly from the market value on the date of this proxy statement.

Effective Time of the Merger

        The Merger Agreement requires the parties to complete the merger after all of the conditions to the completion of the merger contained in the Merger Agreement are satisfied or waived, including, among others, the adoption of the Merger Agreement by the stockholders of Madrigal and Synta and the approval by the Synta stockholders of the merger, the Merger Agreement and the issuance of Synta common stock and the amendment to Synta's restated certificate of incorporation effecting the proposed reverse stock split. The merger will become effective upon the filing of a certificate of merger with the Secretary of State of the State of Delaware or at such later time as is agreed by Synta and Madrigal and specified in the certificate of merger. Neither Synta nor Madrigal can predict the exact timing of the completion of the merger.

Regulatory Approvals

        Synta must comply with applicable federal and state securities laws and the rules and regulations of The NASDAQ Global Market in connection with the issuance of shares of Synta common stock and the filing of this proxy statement with the SEC.

Tax Treatment of the Merger

        Synta, Saffron Merger Sub and Madrigal intend the merger, together with the issuance of shares of Synta common stock to Madrigal stockholders, to qualify as a reorganization within the meaning of Section 368(a) of the Internal Revenue Code of 1986, as amended, or the Code. Each of Synta, Saffron Merger Sub and Madrigal will use its commercially reasonable efforts to cause the merger, together with the issuance of shares of Synta common stock to Madrigal's stockholders, to qualify as a reorganization within the meaning of Section 368(a) of the Code, and not to permit or cause any affiliate or any subsidiary of Synta or Madrigal to, take any action or cause any action to be taken which would or could reasonably be expected to prevent or impede the merger from qualifying as a reorganization under Section 368(a) of the Code.

NASDAQ Stock Market Listing

        Synta common stock currently is listed on The NASDAQ Global Market under the symbol "SNTA." Synta has agreed to use commercially reasonable efforts to obtain approval for listing on The NASDAQ Global Market (or such other NASDAQ market on which Synta's common stock is then listed) of the shares of Synta common stock that Madrigal stockholders will be entitled to receive pursuant to the merger. Madrigal agreed to use its commercially reasonable efforts to provide the information required for an initial listing application pursuant to NASDAQ Stock Market Rule 5110 and to fully cooperate and participate in preparing such application and obtaining such listing.

        Prior to completion of the merger, Synta intends to file an initial listing application with The NASDAQ Global Market or The NASDAQ Capital Market pursuant to NASDAQ Stock Market's

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"change of control" rules. If such application is accepted, Synta anticipates that its common stock will be listed on The NASDAQ Global Market or The NASDAQ Capital Market following the closing of the merger under the trading symbol "MDGL."

Anticipated Accounting Treatment

        Synta currently expects to treat the merger as a purchase by Madrigal of Synta under GAAP. Under the purchase method of accounting, the assets and liabilities of Synta will be recorded, as of the completion of the merger, at their respective fair values, in the financial statements of Madrigal. The financial statements of Madrigal issued after the completion of the merger will reflect these values, but will not be restated retroactively to reflect the historical financial position or results of operations of Synta.

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THE MERGER AGREEMENT

General

        The following is a summary of the material terms of the Merger Agreement. A copy of the Merger Agreement is attached as Annex A to this proxy statement and is incorporated by reference into this proxy statement. The Merger Agreement has been attached to this proxy statement to provide you with information regarding its terms. It is not intended to provide any other factual information about Synta, Madrigal or Saffron Merger Sub. The following description does not purport to be complete and is qualified in its entirety by reference to the Merger Agreement. You should refer to the full text of the Merger Agreement for details of the merger and the terms and conditions of the Merger Agreement.

        The Merger Agreement contains representations and warranties that Synta and Madrigal have made to one another as of specific dates. These representations and warranties have been made for the benefit of the other parties to the Merger Agreement and may be intended not as statements of fact but rather as a way of allocating the risk to one of the parties if those statements prove to be incorrect. In addition, the assertions embodied in the representations and warranties are qualified by information in confidential disclosure schedules exchanged by the parties in connection with signing the Merger Agreement. While Synta and Madrigal do not believe that these disclosure schedules contain information required to be publicly disclosed under the applicable securities laws, other than information that has already been so disclosed, the disclosure schedules do contain information that modifies, qualifies and creates exceptions to the representations and warranties set forth in the attached Merger Agreement. Accordingly, you should not rely on the representations and warranties as current characterizations of factual information about Synta or Madrigal, because they were made as of specific dates, may be intended merely as a risk allocation mechanism between Synta, Saffron Merger Sub and Madrigal and are modified by the disclosure schedules.

Structure

        Subject to the terms and conditions of the Merger Agreement, and in accordance with Delaware law, at the completion of the merger, Saffron Merger Sub, a wholly-owned subsidiary of Synta formed by Synta in connection with the merger, will merge with and into Madrigal, with Madrigal surviving as a wholly-owned subsidiary of Synta.

Completion and Effectiveness of the Merger

        The merger will be completed as promptly as practicable after all of the conditions to completion of the merger are satisfied or waived, including the approval of the stockholders of Synta. Synta and Madrigal are working to complete the merger as quickly as practicable and expect that the merger will be completed during the third quarter of 2016. However, Synta and Madrigal cannot predict the exact timing of the completion of the merger because it is subject to various conditions.

Merger Consideration

        At the effective time of the merger, each outstanding share of common stock of Madrigal will be converted into the right to receive 5.5740 shares of Synta common stock, subject to adjustment to account for the proposed reverse stock split to be implemented prior to the closing of the merger.

        The Merger Agreement does not include a price-based termination right, so there will be no adjustment to the total number of shares of Synta common stock that Madrigal stockholders will be entitled to receive for changes in the market price of Synta common stock. Accordingly, the market value of the shares of Synta common stock issued pursuant to the merger will depend on the market value of the shares of Synta common stock at the time the merger closes, and could vary significantly from the market value on the date of this proxy statement.

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Synta Stock and Options

        Each share of Synta common stock issued and outstanding at the time of the merger will remain issued and outstanding and those shares will be unaffected by the merger. Synta stock options and other equity awards that are outstanding immediately prior to the effective time of the merger will also remain outstanding and be unaffected by the merger, provided that there will be an adjustment to the exercise price and number of shares underlying these options and equity awards to account for the proposed reverse stock split. As of the closing of the merger, current Synta stockholders are expected to own approximately 36% of the combined company immediately after the completion of the merger. This calculation does not contemplate outstanding Synta option awards, all of which have an exercise price greater than the market price of Synta common stock as of May 1, 2016 and will remain outstanding under their existing terms following the merger, nor does it include equity awards in the amount of 20,825,936 shares of common stock of the combined company that are expected to be granted immediately after the completion of the merger to Paul A. Friedman, M.D., and Rebecca Taub, M.D., as executive officers of the combined company.

Procedures for Exchanging Madrigal Stock Certificates

        Promptly after the effective time of the merger, Synta will mail to each holder of record of Madrigal capital stock a letter of transmittal and instructions for surrendering the record holder's stock certificates in exchange for the shares of Synta common stock. Upon proper surrender of Madrigal stock certificates together with a properly completed and duly executed letter of transmittal in accordance with Synta's instructions, the holder of such Madrigal stock certificates will be entitled to receive shares representing the number of whole shares of Synta common stock issuable to such holder pursuant to the merger and cash in lieu of any fractional share of Synta common stock issuable to such holder. The surrendered certificates representing Madrigal common stock will be cancelled.

        After the effective time of the merger, each certificate representing shares of Madrigal common stock that has not been surrendered will represent only the right to receive shares of Synta common stock issuable pursuant to the merger and cash in lieu of any fractional share of Synta common stock to which the holder of any such certificate is entitled. No interest will be paid or accrued on any cash in lieu of fractional shares payable to holders of Madrigal stock certificates.

        Any holder or former holder of Madrigal common stock may be subject to withholding under the Code, or under another provision of state, local or foreign tax law. To the extent such amounts are withheld and paid to the appropriate governmental entity, they will be treated as having been paid to the person to whom such amounts would otherwise have been paid.

        HOLDERS OF MADRIGAL COMMON STOCK SHOULD NOT SEND IN THEIR MADRIGAL STOCK CERTIFICATES UNTIL THEY RECEIVE A LETTER OF TRANSMITTAL FROM SYNTA WITH INSTRUCTIONS FOR THE SURRENDER OF MADRIGAL STOCK CERTIFICATES.

Fractional Shares

        No fractional shares of Synta common stock will be issuable pursuant to the merger to Madrigal stockholders. Instead, each Madrigal stockholder who would otherwise be entitled to receive a fraction of a share of Synta common stock, after aggregating all fractional shares of Synta common stock issuable to such stockholder, will be entitled to receive a cash payment rounded up to the nearest cent in an amount determined by multiplying the closing price per share of Synta common stock on The NASDAQ Global Market (or such other NASDAQ market on which Synta common stock then trades) on the closing date by the fraction of a share of Synta common stock to which such holder would otherwise be entitled.

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Representations and Warranties

        The Merger Agreement contains customary representations and warranties made by Synta and Madrigal relating to their respective businesses, as well as other facts pertinent to the merger. These representations and warranties are subject to materiality, knowledge and other similar qualifications in many respects and expire at the effective time of the merger or termination of the Merger Agreement, as further described below. The representations and warranties of each of Synta and Madrigal have been made solely for the benefit of the other parties and those representations and warranties should not be relied on by any other person. In addition, those representations and warranties may be intended not as statements of actual fact, but rather as a way of allocating risk among the parties, may have been modified by the disclosure schedules delivered in connection with the Merger Agreement, are subject to the materiality standard described in the Merger Agreement, which may differ from what may be viewed as material by you, will not survive completion of the merger and cannot be the basis for any claims under the Merger Agreement by the other parties after termination of the Merger Agreement, and were made only as of the date of the Merger Agreement or another date as is specified in the Merger Agreement.

        Madrigal made a number of representations and warranties to Synta and Saffron Merger Sub in the Merger Agreement, including representations and warranties relating to the following matters:

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        Synta and Saffron Merger Sub made a number of representations and warranties to Madrigal in the Merger Agreement, including representations and warranties relating to the following subject matters:

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        As noted above, significant portions of the representations and warranties are qualified as to "materiality" or "material adverse effect." Under the Merger Agreement, a material adverse effect means any change, circumstance, condition, development, effect, event, occurrence, result or state of facts that, individually or when taken together with any other such change, circumstance, condition, development, effect, event, occurrence, result or state of facts, has or would reasonably be expected to: (i) prevent or materially delay the ability of the parties to complete the transactions contemplated by the Merger Agreement, or (ii) have a material adverse effect on the business, financial condition, assets, liabilities or results of operations of Synta and its subsidiaries, taken as a whole, or Madrigal, except that none of the following, as they apply to Synta and its subsidiaries, taken as a whole, or Madrigal, will be taken into account in determining whether there has been a material adverse effect:

        In addition, no change, circumstance, condition, development, effect, event, occurrence, result or state of facts relating to the asset relating to Synta's development of oncology medicines, including assets relating to the ganetespib, STA-12-8666 and heat shock protein 90 compounds, shall be taken into account in determining whether there has been a material adverse effect for Synta.

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Covenants; Conduct of Business Pending the Merger

        During the period commencing on April 13, 2016 and ending at the earlier of the date of termination of the Merger Agreement and the effective time of the merger, Madrigal agreed that it will conduct its business in the ordinary course and in compliance with all applicable laws, rules, regulations, and certain contracts, and to take other agreed-upon actions, including, without limitation, using its commercially reasonable efforts to preserve intact its current business organization; keeping available the services of its current key employees, officers and other employees and maintaining its relations and goodwill with suppliers, customers, landlords, creditors, licensors, licensees, employees and others Madrigal has business relationships with; providing Synta prompt notice upon the occurrence of certain events or discovery of certain conditions, facts or circumstances; and using commercially reasonable efforts to apply the proceeds of Madrigal's private placement in accordance with its operating budget. During the same period, Synta also agreed that it will conduct its business in the ordinary course and in compliance with all applicable laws, rules, regulations and certain contracts, and to take other agreed-upon actions, including, without limitation, providing Madrigal prompt notice upon the occurrence of certain events or discovery of certain conditions, facts or circumstances.

        Synta and Madrigal also agreed that prior to the effective time of the merger, subject to certain limited exceptions set forth in the Merger Agreement, without the consent of the other party, each of Synta and Madrigal would not, and Synta would not cause or permit any of its subsidiaries to:

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No Solicitation

        The Merger Agreement contains provisions prohibiting Synta and Madrigal from seeking a competing transaction, subject to specified exceptions described below. Under these "no solicitation" provisions, each of Synta and Madrigal has agreed that neither Synta and its subsidiaries nor Madrigal, nor any of their respective officers, directors, employees, representatives, affiliates, advisors or agents shall directly or indirectly (other than, solely in response to an unsolicited inquiry, to refer the inquiring person to the Merger Agreement and to limit its conversation or other communication exclusively to such referral):

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        However, prior to the approval of the proposals relating to the merger set forth in this proxy statement at the meeting of the stockholders of Synta or by written consent of Madrigal stockholders (unless, in either case, the Merger Agreement is earlier terminated), as the case may be, either Synta or Madrigal may, after providing written notice to the other party, furnish nonpublic information to and engage in discussions or negotiations with any third-party that makes an unsolicited bona fide written competing proposal that its board of directors in good faith, after consultation with its outside legal counsel and financial advisors, has determined constitutes or would reasonably be expected to lead to a superior competing proposal, only if:

        Synta and Madrigal will notify the other no later than 24 hours after receipt of any inquiries, discussions, negotiations, proposals or expressions of interest with respect to a competing proposal, and any such notice will be made orally and in writing and will indicate in reasonable detail the terms and conditions of such proposal, inquiry or contact, including price, and the identity of the offeror. Both Synta and Madrigal will keep the other informed, on a current basis, of the status and material developments (including any changes to the terms) of such competing proposal.

        A competing proposal is any of the following proposals, indications of interest, or offers, other than transactions contemplated by the Merger Agreement:

        A superior competing proposal is any unsolicited bona fide competing proposal (with all references to 15% in the definition of competing proposal being treated as references to 100% for these purposes) made by a third-party that the board of directors of either Synta or Madrigal, as the case may be, determines in good faith, after consultation with its outside legal counsel and financial advisor, and after taking into account all financial, legal, regulatory, and other aspects of the competing proposal, that the competing proposal is more favorable from a financial point of view to its stockholders than as provided in the Merger Agreement, is not subject to any financing condition, is reasonably capable of

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being completed on the terms proposed without unreasonable delay and includes termination rights on terms no less favorable than the terms set forth in the Merger Agreement, all from a third-party capable of performing such terms.

        Madrigal, at any time prior to the approval of the issuance of the shares of Synta common stock pursuant to the merger, may terminate the Merger Agreement if the board of directors, and/or any committee of the board of directors, of Synta has made a change of recommendation or if Synta fails to include in this proxy statement the recommendation of its board of directors. In addition, Synta may terminate the Merger Agreement in connection with Synta entering into a definitive agreement to effect a superior competing proposal. In either case in which the Merger Agreement is terminated, Synta agreed to pay to Madrigal a termination fee of $1.25 million. See "—Termination of the Merger Agreement and Termination Fee" below for a more complete discussion of the termination fees.

        In addition, neither the board of directors nor any committee of the board of directors of Madrigal may make a change of recommendation, but the board of directors of Madrigal is not prohibited from making disclosure to Madrigal stockholders, if in its good faith judgment, after consultation with its outside legal counsel, such disclosure would be required to comply with its fiduciary duties under applicable law.

        A "change of recommendation" by the board of directors and/or any committee of the board of directors of Synta or Madrigal, as the case may be, occurs if such board and/or committee:

        Synta, however, is permitted to make a change of recommendation if the board of directors of Synta determines in good faith, after consultation with outside legal counsel and financial advisors that a change of recommendation is required in order to comply with its fiduciary duties under applicable laws either based upon:

but in each case only at a time that is prior to the requisite approval of the Synta stockholders to complete the merger and after the end of the third business day following Madrigal's receipt of written notice advising Madrigal that the board of directors of Synta desires to effect a change of recommendation. This three-day period is referred to as the Notice Period. In addition, Synta must provide Madrigal with a reasonable opportunity to make adjustments in the terms and conditions of the Merger Agreement and negotiate in good faith with Madrigal with respect thereto during the Notice Period, in each case as would enable the board of directors of Synta or committee of the board of directors of Synta to conclude that the intervening event is no longer a basis for any change of

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recommendation or the competing proposal that was determined to be a superior competing proposal is no longer a superior competing proposal. Any material changes to the financial terms or any material change to other material terms of such superior competing proposal occurring prior to the board of directors of Synta's effecting a change of recommendation will require Synta to provide to Madrigal a new notice and a new Notice Period of two rather than three business days.

Disclosure Documents

        As promptly as practicable following the date of the Merger Agreement, Synta agreed to prepare and file this proxy statement with the SEC. Each of Synta and Madrigal agreed to use their commercially reasonable efforts to cause the proxy statement to comply with the applicable rules and regulations promulgated by the SEC and to promptly notify the other party of, cooperate with each other with respect to and promptly respond to any comments from the SEC or its staff. Each of Synta, Saffron Merger Sub and Madrigal agreed to furnish all information concerning itself and their subsidiaries, as applicable, to the other parties as the other parties may reasonably request in connection with such actions and the preparation of the proxy statement. As promptly as practicable, and in no event later than 30 days after the date of the Merger Agreement, Madrigal agreed to furnish to Synta all such information concerning Madrigal to be included in this proxy statement and to cooperate with Synta to file this proxy statement within such 30-day period. Synta agreed to use commercially reasonable efforts to cause this proxy statement to be mailed to its stockholders as promptly as practicable, and in no event later than five business days, following the clearance of this proxy statement by the SEC.

Resale Registration Statement

        Within 60 days following the closing date of the merger, Synta agreed to prepare and file with the SEC a registration statement on Form S-3 (or other form if Form S-3 is not available) covering the resale of the shares of Synta common stock issued to Madrigal stockholders in the merger. Synta agreed to use commercially reasonable efforts to cause the registration statement to be declared effective as soon as possible following the filing of the registration statement and be maintained effective until the earliest to occur of: (i) the second anniversary of the date the registration statement is first declared effective, or (ii) the date that all of the shares of Synta common stock issued to Madrigal stockholders in the merger have actually been sold. For not more than 60 consecutive days or for a total of not more than 120 days in any 12 month period, Synta may suspend the use of any prospectus included in the registration statement if Synta's board of directors determines in good faith that such suspension is necessary to (a) delay the disclosure of material non-public information concerning Synta, the disclosure of which at the time is not, in the good faith opinion of Synta's board of directors, in the best interests of Synta and its stockholders, or (b) amend or supplement the registration statement or the related prospectus so that the registration statement or prospectus will not include an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein, in the case of the prospectus in light of the circumstances under which they were made, not misleading.

Meeting of Synta's Stockholders

        Synta is obligated under the Merger Agreement to call, give notice of, convene and hold a meeting of its stockholders for the purposes of voting on the Merger Agreement and the issuance of shares of Synta common stock pursuant to the merger and to amend its certificate of incorporation to effect the reverse stock split. The Synta stockholders' meeting will be held (on a date selected by Synta in consultation with Madrigal) as promptly as practicable, and in any event not later than 45 days after the date that the definitive proxy statement is filed with the SEC. If on the scheduled date of the Annual Meeting, Synta has not obtained the requisite approval of its stockholders, Synta will have the right to adjourn or postpone the stockholder meeting to a later date or dates, such later date or dates not to exceed 30 days from the original date that the stockholder meeting was scheduled.

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        Madrigal is obligated under the Merger Agreement to take all action necessary in accordance with the Merger Agreement, applicable law, and Madrigal's restated certificate of incorporation and bylaws, to obtain, within 24 hours after the Merger Agreement was executed by the parties, adoption of the Merger Agreement and approval of the merger by written consent of Madrigal's stockholders, which Madrigal obtained on the date the Merger Agreement was executed.

Regulatory Approvals

        Neither Synta nor Madrigal is required to make any filings or to obtain approvals or clearances from any antitrust regulatory authorities in the United States or other countries to complete the merger. In the United States, Synta must comply with applicable federal and state securities laws and The NASDAQ Stock Market rules and regulations in connection with the issuance of shares of Synta's common stock in the merger and the filing with the SEC of this proxy statement. The Merger Agreement provides that Madrigal and Synta shall respond as promptly as is practicable in compliance with: (i) any inquiries or requests received from the Federal Trade Commission or the Department of Justice for information or documentation; and (ii) any inquiries or requests received from any other governmental body in connection with antitrust or competition matters.

Indemnification of Officers and Directors

        Pursuant to the Merger Agreement, upon the completion of the merger, Synta and Saffron Merger Sub agreed that all rights to indemnification, exculpation or advancement of expenses now existing in favor of, and all limitations on the personal liability of each present and former director, officer, employee, fiduciary or agent of Synta or Madrigal as provided for in their respective organizational documents in effect as of the date of the Merger Agreement, will continue to be honored and in full force and effect for a period of six years after the closing of the merger. The certificate of incorporation and by-laws of the surviving corporation will contain provisions with respect to indemnification, exculpation from liability and advancement of expenses that are at least as favorable as those currently in Madrigal's organizational documents, and during such six year period following the closing of the merger, Synta will not amend, repeal or otherwise modify such provisions in any manner that would materially and adversely affect the rights of individuals who at any time prior to the closing of the merger was a director, officer, employee, fiduciary or agent of Madrigal in respect of actions or omissions occurring at or prior to the closing of the merger. From and after the closing of the merger, Synta and the surviving corporation also agreed, jointly and severally, to indemnify and hold harmless the present and former officers, directors, employees, fiduciaries and agents of Madrigal in respect of acts or omissions occurring prior to the closing of the merger to the extent provided in certain written indem