X0306 4 2021-02-18 0 0001662579 C4 Therapeutics, Inc. CCCC 0001132945 COHEN MARC A C/O C4 THERAPEUTICS, INC. 490 ARSENAL WAY #200 WATERTOWN MA 02472 1 0 1 0 Common Stock 2021-02-18 4 M 0 536 2.11 A 5566 D Common Stock 1852207 I See Footnote Common Stock 2484425 I By Cobro Ventures Opportunity Fund, L.P. Stock Option (Right to Buy) 2.11 2021-02-18 4 M 0 536 0.00 D 2026-07-12 Common Stock 536 3209 D 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. 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. 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. /s/ Jolie M. Siegel, Attorney-in-Fact 2021-02-19