Sec Form 4 Filing - COHEN MARC A @ C4 Therapeutics, Inc. - 2021-02-18

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 COHEN MARC A 2. Issuer Name and Ticker or Trading Symbol C4 Therapeutics, Inc. [ CCCC] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O C4 THERAPEUTICS, INC., 490 ARSENAL WAY #200 3. Date of Earliest Transaction (MM/DD/YY) 02/18/2021 (Street) WATERTOWN, MA02472 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ 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 02/18/2021 M 536 A $ 2.11 5,566 D Common Stock 1,852,207 I See Footnote ( 1 ) Common Stock 2,484,425 I By Cobro Ventures Opportunity Fund, L.P. ( 2 )

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 Stock Option (Right to Buy) $ 2.11 02/18/2021 M 536 ( 3 ) 07/12/2026 Common Stock 536 $ 0 3,209 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other COHEN MARC A C/O C4 THERAPEUTICS, INC. 490 ARSENAL WAY #200 WATERTOWN, MA02472 X X Signatures /s/ Jolie M. Siegel, Attorney-in-Fact 02/19/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Shares held by Reporting Person as trustee of the Marc Andrew Cohen Revocable Trust. The Reporting Person disclaims beneficial ownership of these shares except to the extent of his pecuniary interest therein. ( 2 )Shares held by Cobro Ventures Opportunity Fund, L.P. ("Cobro Ventures"). The Reporting Person serves as a manager of Cobro Opportunity Fund GP, LLC, the general partner of Cobro Ventures, and may be deemed to exercise voting and investment power over the shares held by Cobro Ventures. The Reporting Person disclaims beneficial ownership of the shares held by Cobro Ventures except to the extent of his pecuniary interest therein. ( 3 )Represents underlying unexercised stock options that were granted on July 13, 2016. The terms of the original grant provide that 12.5% of this option vested and became exercisable on December 31, 2016, with the remainder vesting in 28 equal quarterly installments thereafter, subject to the Reporting Person's continuous service through each such date.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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