Sec Form 4 Filing - Topspin Fund L.P. @ CONSTELLATION PHARMACEUTICALS INC - 2018-07-23

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Topspin Fund L.P. 2. Issuer Name and Ticker or Trading Symbol CONSTELLATION PHARMACEUTICALS INC [ CNST] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 3 EXPRESSWAY PLAZA 3. Date of Earliest Transaction (MM/DD/YY) 07/23/2018 (Street) ROSLYN HEIGHTS, NY11577 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 07/23/2018 C 445,270 A 445,270 D ( 2 ) Common Stock 07/23/2018 C 1,277,984 A 1,277,984 I ( 3 ) By Funds Common Stock 07/23/2018 C 54,770 A 54,770 I ( 4 ) By MSSB C/F Leo A. Guthart

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Series E Preferred Stock ( 1 ) 07/23/2018 C 177,777 ( 1 ) ( 1 ) Common Stock 20,762 $ 0 0 D ( 2 ) Series E-1 Preferred Stock ( 1 ) 07/23/2018 C 173,408 ( 1 ) ( 1 ) Common Stock 15,750 $ 0 0 D ( 2 ) Series F Preferred Stock ( 1 ) 07/23/2018 C 4,500,000 ( 1 ) ( 1 ) Common Stock 408,758 $ 0 0 D ( 2 ) Series E Preferred Stock ( 1 ) 07/23/2018 C 6,222,222 ( 1 ) ( 1 ) Common Stock 726,678 $ 0 0 I ( 3 ) By Funds Series E-1 Preferred Stock ( 1 ) 07/23/2018 C 6,069,332 ( 1 ) ( 1 ) Common Stock 551,306 $ 0 0 I ( 3 ) By Funds Series E Preferred Stock ( 1 ) 07/23/2018 C 266,667 ( 1 ) ( 1 ) Common Stock 31,143 $ 0 0 I ( 4 ) By MSSB C/F Leo A. Guthart Series E-1 Preferred Stock ( 1 ) 07/23/2018 C 260,114 ( 1 ) ( 1 ) Common Stock 23,627 $ 0 0 I ( 4 ) By MSSB C/F Leo A. Guthart

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Topspin Fund L.P. 3 EXPRESSWAY PLAZA ROSLYN HEIGHTS, NY11577 X Topspin Biotech Fund II, L.P. 3 EXPRESSWAY PLAZA ROSLYN HEIGHTS, NY11577 X LG Management, LLC 3 EXPRESSWAY PLAZA ROSLYN HEIGHTS, NY11577 X GUTHART LEO 3 EXPRESSWAY PLAZA ROSLYN HEIGHTS,, NY11577 X Signatures /s/ Leo A. Guthart 07/23/2018 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On July 23, 2018, the Series E-1 and Series F Preferred Stock converted into Common Stock on a 11.009-for-one basis, and the Series E Preferred Stock converted into Common Stock on a 8.56256-for-one basis, upon the closing of the Issuer's initial public offering without payment of consideration. The Series E, Series E-1 and Series F Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial pubic offering. The shares had no expiration date. ( 2 )The securities are directly held by Topspin Fund L.P. LG Management, LLC, the general partner of Topspin Fund L.P., may be deemed to have voting and dispositive power with respect to the shares. Leo A. Guthart, the managing member of LG Management, LLC, may also be deemed to have voting and dispositive power with respect to the shares. Each of LG Management, LLC and Leo A. Guthart disclaims beneficial ownership of the shares, except to the extent of their respective indirect pecuniary interests in such shares. ( 3 )The securities are directly held by Topspin Biotech Fund L.P. LG Management, LLC, the general partner of Topspin Biotech Fund L.P., may be deemed to have voting and dispositive power with respect to the shares. Leo A. Guthart, the managing member of LG Management, LLC, may also be deemed to have voting and dispositive power with respect to the shares. Each of LG Management, LLC and Leo A. Guthart disclaims beneficial ownership of the shares, except to the extent of their respective indirect pecuniary interests in such shares. ( 4 )The securities are held directly by individual retirement accounts in the name of Leo A. Guthart and as a result Leo A Guthart may be deemed to be the beneficial owner of such shares. Leo A. Guthart disclaims beneficial ownership of such shares, except to the extent of his indirect pecuniary interest in such shares.

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