Seres Therapeutics (MCRB) officer trades RSU shares under 10b5-1 plan

Rhea-AI Filing Summary

Seres Therapeutics, Inc. officer Matthew R. Henn reported RSU vesting and related share movements. On February 15, 2026, he acquired 141 and 98 shares of common stock through the exercise and settlement of restricted stock units, plus another 239 shares, and then sold 89 common shares at $8.47 per share. The sale was made under a pre-arranged Rule 10b5-1 instruction adopted on April 13, 2023, solely to cover taxes triggered by the RSU vesting. Following these transactions, he directly held 7,677 common shares.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

X

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Henn Matthew R

(Last) (First) (Middle)

C/O SERES THERAPEUTICS, INC.

101 CAMBRIDGE PARK DRIVE

(Street)

CAMBRIDGE MA 02140

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Seres Therapeutics, Inc. [ MCRB ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	See Remarks

3. Date of Earliest Transaction (Month/Day/Year)
02/15/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

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
Common Stock	02/15/2026		M		239	A	(1)	7,766	D
Common Stock	02/15/2026		S(2)		89	D	$8.47	7,677	D

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 Securities Underlying Derivative Security (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: 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
Restricted Stock Units	(1)	02/15/2026		M			141	(3)	(3)	Common Stock	141	$0	563	D
Restricted Stock Units	(1)	02/15/2026		M			98	(4)	(4)	Common Stock	98	$0	780	D

Explanation of Responses:

1. Each restricted stock unit represents a contingent right to receive one share of Issuer common stock.

2. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 instruction adopted by the reporting person on April 13, 2023, solely with the intent to cover taxes in connection with the vesting of the restricted stock units.

3. The restricted stock units vested and settled as to 25% of the restricted stock units on February 15, 2024. The remainder of the restricted stock units have vested and settled or will vest and settle in 12 equal quarterly installments thereafter. The restricted stock units have no expiration date.

4. The restricted stock units vested and settled as to 25% of the restricted stock units on February 15, 2025. The remainder of the restricted stock units have vested and settled or will vest and settle in 12 equal quarterly installments thereafter. The restricted stock units have no expiration date.

Remarks:

Chief Scientific Officer and EVP

	/s/ Thomas J. DesRosier, attorney-in-fact for Matthew R. Henn	02/18/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* 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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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FAQ

What insider transactions did MCRB officer Matthew R. Henn report?

Matthew R. Henn reported RSU vesting and related share movements. He acquired shares via exercises of restricted stock units and sold 89 common shares at $8.47 per share, all dated February 15, 2026, leaving him with 7,677 directly held common shares.

How many Seres Therapeutics (MCRB) shares did the officer sell and at what price?

He sold 89 shares of Seres Therapeutics common stock. The sale was executed at a price of $8.47 per share. This transaction was reported as an open-market or private sale under transaction code S on February 15, 2026.

Were the MCRB share sales by Matthew R. Henn under a Rule 10b5-1 plan?

Yes. The filing states the sales were effected under a Rule 10b5-1 instruction adopted on April 13, 2023. It further explains the instruction was used solely to cover taxes arising from the vesting of the restricted stock units.

How many Seres Therapeutics shares did the RSU exercises deliver to the officer?

The RSU exercises delivered 141 and 98 shares of common stock, plus an additional 239 shares from derivative conversion. Each restricted stock unit represents a contingent right to receive one share of common stock with no expiration date described for the units.

What is the vesting schedule for the reported Seres Therapeutics restricted stock units?

One RSU grant vested 25% on February 15, 2024, with the remainder vesting in 12 equal quarterly installments. Another grant vested 25% on February 15, 2025, with the balance also vesting in 12 equal quarterly installments. The RSUs have no expiration date.

How many Seres Therapeutics common shares does Matthew R. Henn hold after these transactions?

After the reported transactions, he directly held 7,677 shares of Seres Therapeutics common stock. This figure reflects the net result of RSU-related acquisitions and the open-market sale of 89 shares on February 15, 2026, as disclosed in the filing.