Sec Form 4 Filing - Casdin Capital, LLC @ 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 Casdin Capital, LLC 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) 1350 AVENUE OF THE AMERICAS, SUITE 2405, 3. Date of Earliest Transaction (MM/DD/YY) 07/23/2018 (Street) NEW YORK, NY10019 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 345,783 A 345,783 I ( 2 ) See footnote Common Stock 07/23/2018 P 266,667 A $ 15 612,450 I ( 2 ) See footnote Common Stock 07/23/2018 C 158,960 A 158,960 I ( 3 ) See footnote

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 1,333,333 ( 1 ) ( 1 ) Common Stock 155,716 $ 0 0 I ( 2 ) See footnote Series E-1 Preferred Stock ( 1 ) 07/23/2018 C 342,435 ( 1 ) ( 1 ) Common Stock 31,104 $ 0 0 I ( 2 ) See footnote Series F Preferred Stock ( 1 ) 07/23/2018 C 1,750,000 ( 1 ) ( 1 ) Common Stock 158,963 $ 0 0 I ( 2 ) See footnote Series F Preferred Stock ( 1 ) 07/23/2018 C 1,750,000 ( 1 ) ( 1 ) Common Stock 158,960 $ 0 0 I ( 3 ) See footnote

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Casdin Capital, LLC 1350 AVENUE OF THE AMERICAS, SUITE 2405 NEW YORK, NY10019 X Casdin Partners Master Fund, L.P. C/O CASDIN CAPITAL LLC 1350 AVENUE OF THE AMERICAS, SUITE 2405 NEW YORK, NY10019 X Casdin Partners GP, LLC C/O CASDIN CAPITAL LLC 1350 AVENUE OF THE AMERICAS, SUITE 2405 NEW YORK, NY10019 X Casdin Eli C/O CASDIN CAPITAL LLC 1350 AVENUE OF THE AMERICAS, SUITE 2405 NEW YORK, NY10019 X Casdin Venture Opportunities Fund, L.P. C/O CASDIN CAPITAL LLC 1350 AVENUE OF THE AMERICAS, SUITE 2405 NEW YORK, NY10019 X CASDIN VENTURE OPPORTUNITIES FUND GP, LLC C/O CASDIN CAPITAL LLC 1350 AVENUE OF THE AMERICAS, SUITE 2405 NEW YORK, NY10019 X Signatures Casdin Capital, LLC, By: Eli Casdin, Managing Member, /s/ Eli Casdin 07/23/2018 Signature of Reporting Person Date Casdin Partners Master Fund, LP, By: Casdin Partners GP, LLC, General Partner, By: Eli Casdin, Managing Member, /s/ Eli Casdin 07/23/2018 Signature of Reporting Person Date Casdin Partners GP, LLC, By: Eli Casdin, Managing Member, /s/ Eli Casdin 07/23/2018 Signature of Reporting Person Date Eli Casdin, /s/ Eli Casdin 07/23/2018 Signature of Reporting Person Date Casdin Venture Opportunities Fund, LP, Casdin Venture Opportunities Fund GP, LLC, General Partner, By: Eli Casdin, Managing Member, /s/ Eli Casdin 07/23/2018 Signature of Reporting Person Date Casdin Venture Opportunities Fund GP, LLC, By: Eli Casdin, Managing Member, /s/ Eli Casdin 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 )These securities are owned directly by Casdin Partners Master Fund, LP and may be deemed to be indirectly beneficially owned by (i) Casdin Capital, LLC, the investment adviser to Casdin Partners Master Fund, LP, (ii) Casdin Partners GP, LLC, the general partner of Casdin Partners Master Fund LP, and (ii) Eli Casdin, the managing member of Casdin Capital, LLC and Casdin Partners GP, LLC. ( 3 )These securities are owned directly by Casdin Venture Opportunities Fund, LP and may be deemed to be indirectly beneficially owned by (i) Casdin Capital, LLC, the investment adviser to Casdin Venture Opportunities Fund, LP, (ii) Casdin Venture Opportunities Fund GP, LLC, the general partner of Casdin Venture Opportunities Fund, LP, and (ii) Eli Casdin, the managing member of Casdin Capital, LLC and Casdin Venture Opportunities Fund GP, LLC.

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