X0508 4 2025-12-17 0001622229 Cogent Biosciences, Inc. COGT 0001709773 Green John L. C/O COGENT BIOSCIENCES, INC. 275 WYMAN STREET, 3RD FLOOR WALTHAM MA 02451 false true false false Chief Financial Officer false Common Stock 2025-12-17 4 A false 50000 0 A 53841 D Common Stock 2025-12-17 4 A false 300000 0 A 353841 D Common Stock 2025-12-17 4 F false 145007 39.45 D 208834 D Stock Option (Right to Buy) 39.45 2025-12-17 4 A false 65000 0.00 A 2035-12-17 Common Stock 65000 65000 D Award of Restricted Stock Units ("RSUs") under the Issuer's 2018 Stock Option and Incentive Plan. The RSUs shall vest with respect to 1/4th of the underlying shares on each anniversary of the grant date, such that the RSUs are fully vested on the fourth anniversary of the grant date, subject to the Reporting Person's continuing service with the Issuer through such dates. Represents acquisition of shares of common stock in connection with the vesting of a performance-based RSU award granted in February 2023 (the "2023 PSUs"). Represents shares surrendered to the Issuer by the Reporting Person to pay required tax withholdings in connection with the vesting of the 2023 PSUs. Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions. This stock option shall vest in equal monthly installments over a four year period, subject to the Reporting Person's continuing service to the Issuer through such dates. /s/ Evan D. Kearns, Attorney-in-Fact 2025-12-19