SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 21)

Synta Pharmaceuticals Corp.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

87162T206

(CUSIP Number)

Mr. Heath N. Weisberg

Caxton Corporation

731 Alexander Road, Bldg. 2

Princeton, New Jersey 08540

(212) 205-6805

(Name, Address and Telephone Number of Person Authorized to

Receive Notices and Communications)

April 13, 2016

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of Section 240.13d-1(e), 240.13d-1(f) or

240.13d-1(g), check the following box. | |

Note:  Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits.  See Section

240.13d-7 for other parties to whom copies are to be sent.

*The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

 

 

 

ITEM 1.

Security and Issuer

No change from the Schedule 13D initially filed on June 18, 2007 and as amended from time to time (the "Schedule 13D").

ITEM 2.

Identity and Background

Item 2 is hereby amended and replaced by the following:

(b)  (i)

The address of Caxton Corporation is 731 Alexander Road, Bldg. 2 Princeton, NJ 08540.

(ii)

The address of Kovner 2012 Family Trust B is 731 Alexander Road, Bldg. 2 Princeton, NJ 08540.

(iii)

The address of Kovner 2015-A Investment Trust is 731 Alexander Road, Bldg. 2 Princeton, NJ 08540.

(iv)

The address of OB Select Opportunities, LLC is 731 Alexander Road, Bldg. 2 Princeton, NJ 08540.

(v)

The address of KFO Holdings LLC is 731 Alexander Road, Bldg. 2 Princeton, NJ 08540.

(vi)

The business address of Mr. Kovner is 731 Alexander Road, Bldg. 2 Princeton, NJ 08540.

(c)  (i)

The principal business of Caxton Corporation is to serve as the manager of certain investment vehicles controlled by Mr. Kovner, including OB Select Opportunities, LLC and KFO Holdings LLC, and as general partner of Caxton Alternative Management LP, an affiliate of Caxton Corporation.

(ii)

The principal business of Kovner 2012 Family Trust B is to serve as an estate planning vehicle for Mr. Kovner and his family.

(iii)

The principal business of Kovner 2015-A Investment Trust is to serve as an estate planning vehicle for Mr. Kovner and his family.

(iv)

The principal business of OB Select Opportunities, LLC is to serve as an investment vehicle for investments in securities.

(v)

The principal business of KFO Holdings LLC is to serve as an investment vehicle for investments in securities.

(vi)

The present principal occupation of Mr. Kovner is Chairman of Caxton Corporation and Caxton Alternative Management LP.

(i)

Caxton Corporation – Delaware.

(ii)

Kovner 2012 Family Trust B – New York.

(iii)

Kovner 2015-A Investment Trust – New York.

(iv)

OB Select Opportunities, LLC – Delaware.

(v)

KFO Holdings LLC – Delaware.

(vi)

Mr. Kovner – United States.

ITEM 3.

Source and Amount of Funds or Other Consideration.

Item 3 is hereby amended by adding the following thereto:

No change from the Schedule 13D/A filed on December 9, 2015.

ITEM 4.

Purpose of Transaction.

Item 4 is hereby amended and replaced by the following:

Each of the shares of Common Stock of the Company that are indicated herein were acquired for investment purposes.  Subject to the restrictions set forth in the Synta Voting Agreement (as described below in Item 6), based on a review of the investment, certain of the Reporting Persons may, in the open market or otherwise, dispose of, or cause to be disposed of, a material portion of Common Stock or other securities of the Company, or derivatives or other instruments related to the securities of the Company.

Mr. Kovner currently serves as a Director of the Company.  In that capacity, he participates in the ordinary course in Board of Directors' related activities and may participate in the management of the Company.

Scott Morenstein, an employee of Caxton Alternative Management LP, serves as a Director of the Company.  Caxton Alternative Management LP is an affiliate of Caxton Corporation, which is a Reporting Person.

On April 13, 2016, the Company, Saffron Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of the Company ("Merger Sub") and Madrigal Pharmaceuticals, Inc., a Delaware corporation ("Madrigal"), entered into an Agreement and Plan of Merger (the "Merger Agreement"), pursuant to which, among other things, subject to the satisfaction or waiver of the conditions set forth in the Merger Agreement, Merger Sub will merge with and into Madrigal, with Madrigal becoming a wholly-owned subsidiary of the Company and the surviving corporation of the merger (the "Merger").  In connection with the Merger Agreement, certain of the Reporting Persons have entered into the Synta Voting Agreement, as described below in Item 6 and filed as Exhibit A to this Schedule 13D.

Except as set forth in this Schedule 13D, none of the Reporting Persons has any plans or proposals that relate to any of the matters referred to in paragraphs (a) through (j) of the instructions to Item 4 of Schedule 13D.

ITEM 5.

Interest in Securities of the Issuer.

Subparagraph (a), (b) and (c) of Item 5 of the Schedule 13D is hereby amended and replaced by the following:

Caxton Corporation disclaims beneficial ownership of the shares of Common Stock owned directly by KFO Holdings LLC, OB Select Opportunities, LLC, and an employee of an affiliate of Caxton Corporation, except to the extent of its pecuniary interest therein.

As a result of the foregoing, Mr. Kovner may be deemed to beneficially own an aggregate of 21,842,662 shares of Common Stock, representing approximately 15.8% of the 137,878,441¹ total shares of Common Stock deemed issued and outstanding.

Mr. Kovner disclaims beneficial ownership of the shares of Common Stock owned directly by KFO Holdings LLC, OB Select Opportunities, LLC and an employee of an affiliate of Caxton Corporation, except to the extent of his pecuniary interest therein.  Mr. Kovner also disclaims beneficial ownership of the shares of Common Stock directly owned by each of the aforementioned trusts.

Except as reported in this statement on Schedule 13D, the Reporting Persons are not believed to have engaged in any other transactions in the Company's securities since the most recent filing of Schedule 13D.

ITEM 6.

Contracts, Arrangements, Understandings or Relationships with Respect to Securities of the Issuer.

Item 6 is hereby amended by adding the following thereto:

As described in Item 4 above, on April 13, 2016, the Company, Merger Sub and Madrigal, entered into a Merger Agreement, pursuant to which, among other things, subject to the satisfaction or waiver of the conditions set forth in the Merger Agreement, Merger Sub will merge with and into Madrigal, with Madrigal becoming a wholly-owned subsidiary of the Company and the surviving corporation of the merger.

In connection with the Merger Agreement, Kovner 2012 Family Trust B, Kovner 2015-A Investment Trust, OB Select Opportunities LLC, KFO Holdings LLC, Mr. Kovner, certain estate planning vehicles of Mr. Kovner's spouse, and an employee of an affiliate of Caxton Corporation have each entered into a voting agreement in favor of Madrigal (the "Synta Voting Agreement").  The Synta Voting Agreement places certain restrictions on the sale or transfer of the shares of the Company held by each of the aforementioned Reporting Persons and covenants on the voting of such shares in favor of approving the transactions contemplated by the Merger Agreement and against any actions that could adversely affect the consummation of the Merger.  The foregoing description of the Synta Voting Agreement and the transactions contemplated thereby does not purport to be complete and is qualified in its entirety by reference to the Synta Voting Agreement, which is filed as Exhibit A hereto and which is incorporated herein by reference.

ITEM 7.

Material to Be Filed as Exhibits

Exhibit A: Form of Synta Voting Agreement dated as of April 13, 2016 entered into by and among the Company, Madrigal and certain of the Reporting Persons, incorporated herein by reference to Exhibit 10.1 of the Company's Form 8-K filed on April 14, 2016.

¹ The number of issued and outstanding shares is based on the 137,806,441 shares of Common Stock reported to be outstanding in the Company's 10-K as of March 10, 2016, adjusted for options held by Mr. Kovner.

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

The original statement shall be signed by each person on whose behalf the statement is filed or his authorized representative. If the statement is signed on behalf of a person by his authorized representative (other than an executive officer or general partner of the filing person), evidence of the representative's authority to sign on behalf of such person shall be filed with the statement: provided, however, that a power of attorney for this purpose which is already on file with the Commission may be incorporated by reference.  The name and any title of each person who signs the statement shall be typed or printed beneath his signature.

ATTENTION: Intentional misstatements or omissions of fact constitute Federal criminal violations (See 18 U.S.C. 1001).