Planned tax sale by Seres Therapeutics (MCRB) officer after RSU vest

Rhea-AI Filing Summary

Seres Therapeutics, Inc. officer Thomas DesRosier reported routine equity compensation activity and a small share sale. On February 15, 2026, he acquired common stock through the exercise and settlement of restricted stock units, then sold 78 shares of common stock at $8.47 per share. The sale was executed under a pre-arranged Rule 10b5-1 instruction adopted on March 2, 2023, solely to cover taxes tied to the restricted stock unit vesting. After these transactions, he continued to hold common stock and restricted stock units directly.

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

OMB Number:			3235-0287
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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^*

DesRosier Thomas

(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		244	A	(1)	7,867	D
Common Stock	02/15/2026		S(2)		78	D	$8.47	7,789	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			133	(3)	(3)	Common Stock	133	$0	531	D
Restricted Stock Units	(1)	02/15/2026		M			111	(4)	(4)	Common Stock	111	$0	890	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 March 2, 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 Legal Officer, EVP, Co-Chief Executive Officer, and Co-President

	/s/ Thomas J. DesRosier	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.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What insider transactions did Thomas DesRosier report for Seres Therapeutics (MCRB)?

Thomas DesRosier reported equity compensation activity and a small sale. He acquired common shares upon restricted stock unit settlement and sold 78 common shares at $8.47 per share on February 15, 2026, as disclosed in the Form 4 filing.

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

He sold 78 shares of Seres Therapeutics common stock. The reported sale price was $8.47 per share on February 15, 2026, according to the Form 4 insider trading disclosure for officer Thomas DesRosier.

Were the Seres Therapeutics (MCRB) insider sales part of a 10b5-1 trading plan?

Yes. The filing states the sales were effected under a Rule 10b5-1 instruction adopted on March 2, 2023. The plan governed transactions executed solely to cover taxes from restricted stock unit vesting and settlement.

What do the restricted stock units in the Seres Therapeutics (MCRB) Form 4 represent?

Each restricted stock unit represents a contingent right to receive one share of Seres Therapeutics common stock. The units vest and settle in scheduled installments over time, with no expiration date, as described in the Form 4 footnotes.

How are the Seres Therapeutics (MCRB) restricted stock units scheduled to vest for this officer?

The restricted stock units vest and settle 25% on a specified February 15 date, then in 12 equal quarterly installments thereafter. The Form 4 notes separate schedules starting February 15, 2024 and February 15, 2025, with no expiration date for the units.