FHTX · Foghorn Therapeutics Inc.

The option vests in full on the first anniversary of the grant date, subject to the reporting person's continued service on the board of directors.

The option vests in full on the first anniversary of the grant date, subject to the reporting person's continued service on the board of directors.

The option vests in full on the first anniversary of the grant date, subject to the reporting person's continued service on the board of directors.

The option vests in full on the first anniversary of the grant date, subject to the reporting person's continued service on the board of directors.

The option vests in full on the first anniversary of the grant date, subject to the reporting person's continued service on the board of directors.

The option vests in full on the first anniversary of the grant date, subject to the reporting person's continued service on the board of directors.

The option vests in full on the first anniversary of the grant date, subject to the reporting person's continued service on the board of directors.

The option vests in full on the first anniversary of the grant date, subject to the reporting person's continued service on the board of directors.

The option vests in full on the first anniversary of the grant date, subject to the reporting person's continued service on the board of directors.

On April 10, 2026, the Adrian H. Gottschalk 2025 Grantor Retained Annuity Trust dated April 25, 2025, of which the Reporting Person is the trustee and sole current beneficiary (the "2025 GRAT"), distributed 59,208 shares of the Issuer's Common Stock to the Living Trust.

On April 10, 2026, the Adrian H. Gottschalk 2025 Grantor Retained Annuity Trust dated April 25, 2025, of which the Reporting Person is the trustee and sole current beneficiary (the "2025 GRAT"), distributed 59,208 shares of the Issuer's Common Stock to the Living Trust.

On April 9, 2026, the Adrian H. Gottschalk 2023 Grantor Retained Annuity Trust dated May 26, 2023, of which the Reporting Person is the trustee and sole current beneficiary (the "2023 GRAT"), distributed 47,497 shares of the Issuer's Common Stock to the Adrian H. Gottschalk Living Trust dated September 8, 2009, of which the Reporting Person is the trustee (the "Living Trust").

On April 9, 2026, the Adrian H. Gottschalk 2023 Grantor Retained Annuity Trust dated May 26, 2023, of which the Reporting Person is the trustee and sole current beneficiary (the "2023 GRAT"), distributed 47,497 shares of the Issuer's Common Stock to the Adrian H. Gottschalk Living Trust dated September 8, 2009, of which the Reporting Person is the trustee (the "Living Trust").

The option vests as to 25% of the underlying shares of common stock on February 23, 2027, and at a rate of 6.25% of the underlying shares thereafter on the first day of each calendar quarter until the option is fully vested.

The option vests as to 25% of the underlying shares of common stock on February 5, 2027, and thereafter at a rate of 6.25% of the underlying shares on the first day of each calendar quarter.

The option vests as to 25% of the underlying shares of common stock on January 30, 2027, and thereafter at a rate of 6.25% of the underlying shares on the first day of each calendar quarter.

The option vests as to 25% of the underlying shares of common stock on January 30, 2027, and thereafter at a rate of 6.25% of the underlying shares on the first day of each calendar quarter.

The option vests as to 25% of the underlying shares of common stock on January 30, 2027, and thereafter at a rate of 6.25% of the underlying shares on the first day of each calendar quarter.

The option vests as to 25% of the underlying shares of common stock on January 30, 2027, and thereafter at a rate of 6.25% of the underlying shares on the first day of each calendar quarter.

The option vests as to 25% of the underlying shares of common stock on January 30, 2027, and thereafter at a rate of 6.25% of the underlying shares on the first day of each calendar quarter.

On January 13, 2026, pursuant to a registered direct offering by the Issuer, Flagship Pioneering Fund VII, L.P. ("Flagship Fund VII") acquired warrants to purchase an aggregate of 4,470,936 shares of Common Stock, consisting of (i) Pre-Funded Warrants to purchase 2,235,468 shares of Common Stock, (ii) Series 1 Warrants to purchase 1,117,734 shares of Common Stock and (iii) Series 2 Warrants to purchase 1,117,734 shares of Common Stock (together with the Series 1 Warrants, the "Series Warrants"). The securities were acquired for a purchase price of $6.7099 per Pre-Funded Warrant and accompanying Series Warrants.

Securities held by Flagship Fund VII. Flagship Pioneering Fund VII General Partner LLC ("Flagship Fund VII GP") is the general partner of Flagship Fund VII. Flagship Pioneering, LLC (f/k/a Flagship Pioneering, Inc., "Flagship Pioneering") is the manager of Flagship Fund VII GP. Noubar B. Afeyan, Ph.D. is the ultimate control person of Flagship Pioneering. Each of the Reporting Persons disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein, if any.

The Series Warrants are exercisable at an initial price of $13.42 per Series 1 Warrant and $20.13 per Series 2 Warrant. Subject to certain exclusions, if prior to June 30, 2027, the Company issues capital stock or securities convertible into or exercisable for capital stock in one or more related transactions primarily for capital raising at a weighted-average common stock equivalent price (the "Weighted-Average Price") below $13.42 per share, the exercise price of a Series Warrant shall reset upon exercise to the midpoint between the initial price and the lowest such Weighted-Average Price, but not below $6.71 per share. The exercise price may be adjusted only once pursuant to this mechanism.

On January 13, 2026, pursuant to a registered direct offering by the Issuer, Flagship Pioneering Fund VII, L.P. ("Flagship Fund VII") acquired warrants to purchase an aggregate of 4,470,936 shares of Common Stock, consisting of (i) Pre-Funded Warrants to purchase 2,235,468 shares of Common Stock, (ii) Series 1 Warrants to purchase 1,117,734 shares of Common Stock and (iii) Series 2 Warrants to purchase 1,117,734 shares of Common Stock (together with the Series 1 Warrants, the "Series Warrants"). The securities were acquired for a purchase price of $6.7099 per Pre-Funded Warrant and accompanying Series Warrants.

Securities held by Flagship Fund VII. Flagship Pioneering Fund VII General Partner LLC ("Flagship Fund VII GP") is the general partner of Flagship Fund VII. Flagship Pioneering, LLC (f/k/a Flagship Pioneering, Inc., "Flagship Pioneering") is the manager of Flagship Fund VII GP. Noubar B. Afeyan, Ph.D. is the ultimate control person of Flagship Pioneering. Each of the Reporting Persons disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein, if any.

The Series Warrants are exercisable at an initial price of $13.42 per Series 1 Warrant and $20.13 per Series 2 Warrant. Subject to certain exclusions, if prior to June 30, 2027, the Company issues capital stock or securities convertible into or exercisable for capital stock in one or more related transactions primarily for capital raising at a weighted-average common stock equivalent price (the "Weighted-Average Price") below $13.42 per share, the exercise price of a Series Warrant shall reset upon exercise to the midpoint between the initial price and the lowest such Weighted-Average Price, but not below $6.71 per share. The exercise price may be adjusted only once pursuant to this mechanism.

On January 13, 2026, pursuant to a registered direct offering by the Issuer, Flagship Pioneering Fund VII, L.P. ("Flagship Fund VII") acquired warrants to purchase an aggregate of 4,470,936 shares of Common Stock, consisting of (i) Pre-Funded Warrants to purchase 2,235,468 shares of Common Stock, (ii) Series 1 Warrants to purchase 1,117,734 shares of Common Stock and (iii) Series 2 Warrants to purchase 1,117,734 shares of Common Stock (together with the Series 1 Warrants, the "Series Warrants"). The securities were acquired for a purchase price of $6.7099 per Pre-Funded Warrant and accompanying Series Warrants.

Securities held by Flagship Fund VII. Flagship Pioneering Fund VII General Partner LLC ("Flagship Fund VII GP") is the general partner of Flagship Fund VII. Flagship Pioneering, LLC (f/k/a Flagship Pioneering, Inc., "Flagship Pioneering") is the manager of Flagship Fund VII GP. Noubar B. Afeyan, Ph.D. is the ultimate control person of Flagship Pioneering. Each of the Reporting Persons disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein, if any.

The options will vest as to one-third of the underlying shares of common stock on each of the first three anniversaries of the date of grant, subject to the recipient's continuing service on the board of directors.

The options will vest as to one-third of the underlying shares of common stock on each of the first three anniversaries of the date of grant, subject to the recipient's continuing service on the board of directors.

On April 25, 2025, the Adrian H. Gottschalk Living Trust dated September 8, 2009 (the "Gottschalk Living Trust"), of which the Reporting Person is the trustee, distributed 300,000 shares of the Issuer's Common Stock to the Adrian H. Gottschalk 2025 Grantor Retained Annuity Trust dated April 25, 2025 (the "Gottschalk 2025 GRAT"), of which the Reporting Person is the trustee and sole current beneficiary.

Consists of 47,497 shares held by the Adrian H. Gottschalk 2023 Grantor Retained Annuity Trust dated May 26, 2023, 300,000 shares held by the Gottschalk 2025 GRAT, and 164,207 shares held by the Gottschalk Living Trust.

On April 25, 2025, the Adrian H. Gottschalk Living Trust dated September 8, 2009 (the "Gottschalk Living Trust"), of which the Reporting Person is the trustee, distributed 300,000 shares of the Issuer's Common Stock to the Adrian H. Gottschalk 2025 Grantor Retained Annuity Trust dated April 25, 2025 (the "Gottschalk 2025 GRAT"), of which the Reporting Person is the trustee and sole current beneficiary.

Consists of 47,497 shares held by the Adrian H. Gottschalk 2023 Grantor Retained Annuity Trust dated May 26, 2023, 300,000 shares held by the Gottschalk 2025 GRAT, and 164,207 shares held by the Gottschalk Living Trust.

On April 9, 2025, the Adrian H. Gottschalk 2023 Grantor Retained Annuity Trust dated May 26, 2023, of which the Reporting Person is the trustee and sole current beneficiary (the "Gottschalk 2023 GRAT"), distributed 197,906 shares of the Issuer's Common Stock to the Adrian H. Gottschalk Living Trust dated September 8, 2009, of which the Reporting Person is the trustee (the "Gottschalk Living Trust").

Consists of 47,497 shares held by the Gottschalk 2023 GRAT and 464,207 shares held by the Gottschalk Living Trust.

On April 9, 2025, the Adrian H. Gottschalk 2023 Grantor Retained Annuity Trust dated May 26, 2023, of which the Reporting Person is the trustee and sole current beneficiary (the "Gottschalk 2023 GRAT"), distributed 197,906 shares of the Issuer's Common Stock to the Adrian H. Gottschalk Living Trust dated September 8, 2009, of which the Reporting Person is the trustee (the "Gottschalk Living Trust").

Consists of 47,497 shares held by the Gottschalk 2023 GRAT and 464,207 shares held by the Gottschalk Living Trust.

The option vests as to 25% of the underlying shares of common stock on January 22, 2026, and thereafter at a rate of 6.25% of the underlying shares on the first day of each calendar quarter.

The option vests as to 25% of the underlying shares of common stock on January 22, 2026, and thereafter at a rate of 6.25% of the underlying shares on the first day of each calendar quarter.

The option vests as to 25% of the underlying shares of common stock on January 22, 2026, and thereafter at a rate of 6.25% of the underlying shares on the first day of each calendar quarter.

The option vests as to 25% of the underlying shares of common stock on January 22, 2026, and thereafter at a rate of 6.25% of the underlying shares on the first day of each calendar quarter.

The option vests as to 25% of the underlying shares of common stock on January 22, 2026, and thereafter at a rate of 6.25% of the underlying shares on the first day of each calendar quarter.

The option vests as to 25% of the underlying shares of common stock on January 22, 2026, and thereafter at a rate of 6.25% of the underlying shares on the first day of each calendar quarter.

The option vests as to 25% of the underlying shares of common stock on January 22, 2026, and thereafter at a rate of 6.25% of the underlying shares on the first day of each calendar quarter.

The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan that was adopted by the reporting person on March 11, 2024.

The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan that was adopted by the reporting person on March 11, 2024.