Flagship Pioneering, LLC - 13 Jan 2026 Form 4 Insider Report for Foghorn Therapeutics Inc. (FHTX)

Signature
Flagship Pioneering, LLC, By: /s/ Noubar B. Afeyan, Ph.D., Title: Sole Member and Manager of Manager
Issuer symbol
FHTX
Transactions as of
13 Jan 2026
Net transactions value
+$14,999,767
Form type
4
Filing time
15 Jan 2026, 17:00:05 UTC
Previous filing
24 May 2024

Reporting Owners (10)

Name Relationship Address Signature Signature date CIK
Flagship Pioneering, LLC Director, 10%+ Owner 55 CAMBRIDGE PARKWAY, SUITE 800E, CAMBRIDGE Flagship Pioneering, LLC, By: /s/ Noubar B. Afeyan, Ph.D., Title: Sole Member and Manager of Manager 15 Jan 2026 0001400240
Flagship Pioneering Fund VII General Partner LLC Director, 10%+ Owner 55 CAMBRIDGE PARKWAY, SUITE 800E, CAMBRIDGE Flagship Pioneering Fund VII General Partner LLC, By: /s/ Noubar B. Afeyan, Ph.D., Title: Sole Member and Manager of Manager of Manager 15 Jan 2026 0001805917
Flagship Pioneering Fund VII, L.P. Director, 10%+ Owner 55 CAMBRIDGE PARKWAY, SUITE 800E, CAMBRIDGE Flagship Pioneering Fund VII, L.P., By: /s/ Noubar B. Afeyan, Ph.D., Title: Sole Member and Manager of Manager of Manager of General Partner 15 Jan 2026 0001805916
Flagship Pioneering Special Opportunities Fund II General Partner LLC Director, 10%+ Owner 55 CAMBRIDGE PARKWAY, SUITE 800E, CAMBRIDGE Flagship Pioneering Special Opportunities Fund II General Partner LLC, By: /s/ Noubar B. Afeyan Ph.D., Title: Sole Member and Manager of Manager 15 Jan 2026 0001826217
Flagship Pioneering Special Opportunities Fund II, L.P. Director, 10%+ Owner 55 CAMBRIDGE PARKWAY, SUITE 800E, CAMBRIDGE Flagship Pioneering Special Opportunities Fund II, L.P., By: /s/ Noubar B. Afeyan Ph.D., Title: Sole Member and Manager of Manager of Manager of General Partner 15 Jan 2026 0001761283
Flagship Ventures Fund V General Partner LLC Director, 10%+ Owner 55 CAMBRIDGE PARKWAY, SUITE 800E, CAMBRIDGE Flagship Ventures Fund V General Partner LLC, By: /s/ Noubar B. Afeyan Ph.D., Title: Manager 15 Jan 2026 0001724575
Flagship Ventures Fund V, L.P. Director, 10%+ Owner 55 CAMBRIDGE PARKWAY, SUITE 800E, CAMBRIDGE Flagship Ventures Fund V, L.P., By: /s/ Noubar B. Afeyan Ph.D., Title: Manager of General Partner 15 Jan 2026 0001627639
Flagship Ventures Opportunities Fund I General Partner LLC Director, 10%+ Owner 55 CAMBRIDGE PARKWAY, SUITE 800E, CAMBRIDGE Flagship Ventures Opportunities Fund I General Partner LLC, By: /s/ Noubar B. Afeyan Ph.D., Title: Manager 15 Jan 2026 0001725004
Flagship Ventures Opportunities Fund I, L.P. Director, 10%+ Owner 55 CAMBRIDGE PARKWAY, SUITE 800E, CAMBRIDGE Flagship Ventures Opportunities Fund I, L.P., By: /s/ Noubar B. Afeyan Ph.D., Title: Manager of General Partner 15 Jan 2026 0001677345
AFEYAN NOUBAR Director, 10%+ Owner 55 CAMBRIDGE PARKWAY, SUITE 800E, CAMBRIDGE /s/ Noubar B. Afeyan, Ph.D. 15 Jan 2026 0001222012

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Underlying Class Amount Exercise Price Ownership Footnotes
transaction FHTX Pre-Funded Warrants to purchase Common Stock Award $14,999,767 +2,235,468 $6.71 2,235,468 13 Jan 2026 Common Stock 2,235,468 $0.000100 By Flagship Pioneering Fund VII, L.P. F1, F2
transaction FHTX Series 1 Warrants to purchase Common Stock Award +1,117,734 1,117,734 13 Jan 2026 Common Stock 1,117,734 $13.42 By Flagship Pioneering Fund VII, L.P. F1, F2, F3
transaction FHTX Series 2 Warrants to purchase Common Stock Award +1,117,734 1,117,734 13 Jan 2026 Common Stock 1,117,734 $20.13 By Flagship Pioneering Fund VII, L.P. F1, F2, F3
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id Content
F1 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.
F2 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.
F3 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.

Remarks:

Douglas G. Cole, a Managing Partner at Flagship Pioneering, serves on the board of directors of the Issuer and has been deputized to represent the Reporting Persons on the board of directors of the Issuer. By virtue of Mr. Cole's representation, for purposes of Section 16 of the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons may be deemed directors by deputization of the Issuer. This filing shall not be deemed an admission that any Reporting Person is a beneficial owner of the securities reported in this filing for purposes of Section 16 of the Exchange Act or otherwise, or is subject to Section 16 of the Exchange Act, and each Reporting Person disclaims beneficial ownership of these securities, except to the extent of such Reporting Person's pecuniary interest therein, if any.