X0508 4 2025-10-28 0001662579 C4 Therapeutics, Inc. CCCC 0002040313 Mahaney Paige C4 THERAPEUTICS, INC. 490 ARSENAL WAY, SUITE 120 WATERTOWN MA 02472 false true false false Chief Scientific Officer false Common Stock 2025-10-28 5 M false 19200 0.00 A 105000 D Common Stock 2025-10-28 4 F false 5644 2.58 D 99356 D Reflects the acquisition of shares of Common Stock upon vesting of a previously disclosed grant of restricted stock units ("RSUs"). The grant of RSUs was initially reported in Table I of the Form 4 filed by the Reporting Person on October 28, 2024. Represents shares withheld by the Issuer to satisfy tax withholding obligations in connection with the vesting and settlement of RSUs and does not represent a sale by the Reporting Person. /s/ Shagha Russell, Attorney-in-Fact 2025-10-30