Statement of Changes in Beneficial Ownership (Form 4)

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b). Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person * Flagship Pioneering, LLC 2. Issuer Name and Ticker or Trading Symbol Foghorn Therapeutics Inc. [FHTX] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 55 CAMBRIDGE PARKWAY, SUITE 800E 3. Date of Earliest Transaction (Month/Day/Year) 01/13/2026 (Street) CAMBRIDGE, MA 02142 4. If Amendment, Date Original Filed (Month/Day/Year) 6. Individual or Joint/Group Filing (Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Pre-Funded Warrants to purchase Common Stock

$0.0001

01/13/2026

A

2,235,468

01/13/2026

01/13/2046

Common Stock

2,235,468

$6.7099(1)

2,235,468

I

By Flagship Pioneering Fund VII, L.P.(2)

Series 1 Warrants to purchase Common Stock

$13.42(3)

01/13/2026

A

1,117,734

01/13/2026

06/30/2027

Common Stock

1,117,734

(1)

1,117,734

I

By Flagship Pioneering Fund VII, L.P.(2)

Series 2 Warrants to purchase Common Stock

$20.13(3)

01/13/2026

A

1,117,734

01/13/2026

12/31/2030

Common Stock

1,117,734

(1)

1,117,734

I

By Flagship Pioneering Fund VII, L.P.(2)

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Flagship Pioneering, LLC 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA 02142	X	X
Flagship Pioneering Fund VII General Partner LLC 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA 02142	X	X
Flagship Pioneering Fund VII, L.P. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA 02142	X	X
Flagship Pioneering Special Opportunities Fund II General Partner LLC 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA 02142	X	X
Flagship Pioneering Special Opportunities Fund II, L.P. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA 02142	X	X
Flagship Ventures Fund V General Partner LLC 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA 02142	X	X
Flagship Ventures Fund V, L.P. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA 02142	X	X
Flagship Ventures Opportunities Fund I General Partner LLC 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA 02142	X	X
Flagship Ventures Opportunities Fund I, L.P. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA 02142	X	X
AFEYAN NOUBAR 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA 02142	X	X

Signatures

Flagship Pioneering, LLC, By: /s/ Noubar B. Afeyan, Ph.D., Title: Sole Member and Manager of Manager		01/15/2026
**Signature of Reporting Person		Date
Flagship Pioneering Fund VII General Partner LLC, By: /s/ Noubar B. Afeyan, Ph.D., Title: Sole Member and Manager of Manager of Manager		01/15/2026
**Signature of Reporting Person		Date
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		01/15/2026
**Signature of Reporting Person		Date
Flagship Pioneering Special Opportunities Fund II General Partner LLC, By: /s/ Noubar B. Afeyan Ph.D., Title: Sole Member and Manager of Manager		01/15/2026
**Signature of Reporting Person		Date
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		01/15/2026
**Signature of Reporting Person		Date
Flagship Ventures Fund V General Partner LLC, By: /s/ Noubar B. Afeyan Ph.D., Title: Manager		01/15/2026
**Signature of Reporting Person		Date
Flagship Ventures Fund V, L.P., By: /s/ Noubar B. Afeyan Ph.D., Title: Manager of General Partner		01/15/2026
**Signature of Reporting Person		Date
Flagship Ventures Opportunities Fund I General Partner LLC, By: /s/ Noubar B. Afeyan Ph.D., Title: Manager		01/15/2026
**Signature of Reporting Person		Date
Flagship Ventures Opportunities Fund I, L.P., By: /s/ Noubar B. Afeyan Ph.D., Title: Manager of General Partner		01/15/2026
**Signature of Reporting Person		Date
/s/ Noubar B. Afeyan, Ph.D.		01/15/2026
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	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.
(2)	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.
(3)	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.

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