X0306 4 2022-05-25 false 0001822462 Foghorn Therapeutics Inc. FHTX 0001831749 Bellon Steven F. 500 TECHNOLOGY SQUARE STE 700 CAMBRIDGE MA 02139 false true false false Chief Scientific Officer Common Stock 2022-05-25 4 M false 675.00 0.73 A 116382.00 D Common Stock 2022-05-25 4 M false 3717.00 3.72 A 120099.00 D Common Stock 50000.00 I See Footnote Stock Options (Right to buy) 0.73 2022-05-25 4 M false 675.00 0.00 D 2028-01-30 Common Stock 675.00 0.00 D Stock Options (Right to buy) 3.72 2022-05-25 4 M false 3717.00 0.00 D 2029-02-13 Common Stock 3717.00 5574.00 D Shares held by the Steven F. Bellon 2021 Irrevocable Trust dated December 3, 2021, of which the Reporting Person's children are the trustees. The option vested at a rate of 6.25% of the underlying shares beginning on April 1, 2018 and thereafter on the first day of each calendar quarter until the option was fully vested. The option vested as to 25% of the underlying shares of common stock on January 30, 2020, the first anniversary of the of the vesting commencement date, and at a rate of 6.25% of the underlying shares thereafter on the first day of each calendar quarter following such first anniversary until the option is fully vested. /s /Allan Reine, M.D., Attorney-in-Fact 2022-05-27