X0306 4 2021-04-05 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 2021-04-05 4 A 0 553 37.51 A 6119 D Common Stock 1852207 I See Footnote Common Stock 2484425 I By Cobro Ventures Opportunity Fund, L.P. These shares were issued in accordance with the Issuer's Non-Employee Director Compensation Policy, pursuant to which the Reporting Person elected to receive shares of the Issuer's common stock in lieu of cash compensation for services as a non-employee director of the Issuer. The price reported in Column 4 is based upon the closing market price of the Issuer's common stock on April 5, 2021. 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. /s/ Jolie M. Siegel, Attorney-in-Fact 2021-04-06