X0609 4 2026-06-09 0001622229 Cogent Biosciences, Inc. COGT 0001663607 Harwin Peter Evan false C/O COGENT BIOSCIENCES, INC. 180 THIRD AVENUE, 4TH FLOOR WALTHAM MA 02451 true false false false false Stock Option (Right to Buy) 31.98 2026-06-09 4 A false 17901 0 A 2036-06-09 Common Stock 17901 17901 D This stock option shall vest in full upon the earlier of the first anniversary of the date of grant or the date of the 2027 Annual Meeting of Stockholders, subject to the Reporting Person's continued service to the Issuer through such date. Under the Reporting Person's arrangement with Fairmount Funds Management LLC (the "Adviser"), the Reporting Person holds the option for one or more investment vehicles managed by the Adviser (each, a "Fairmount Fund"). The Reporting Person is obligated to turn over to the Adviser any net cash or stock received from the option for the benefit of such Fairmount Fund. The Reporting Person therefore disclaims beneficial ownership of the option and underlying common stock. /s/ Evan D. Kearns, Attorney-in-Fact 2026-06-11