[Form 4] Seres Therapeutics, Inc. Insider Trading Activity

Rhea-AI Filing Summary

On July 1, 2025, Seres Therapeutics (MCRB) filed a Form 4 indicating that non-employee director Claire Fraser received a stock option for 6,452 shares of common stock at an exercise price of $10.71. The option expires on July 1, 2035 and vests in four equal quarterly installments beginning October 1, 2025 and ending July 1, 2026, with the final tranche accelerated if the 2026 annual shareholder meeting occurs earlier. Following the grant, Fraser beneficially owns 6,452 derivative securities; no open-market acquisitions or sales of common stock were reported. The transaction is routine director compensation, non-cash in nature, and does not materially affect Seres Therapeutics’ share count or cash position.

Insights

Financial Analyst

TL;DR: Routine director option grant; negligible dilution; neutral to valuation.

The grant represents less than 0.02 % of Seres Therapeutics’ 34 million outstanding shares, so dilution is immaterial. Because the option is priced at $10.71, value is contingent on future share appreciation. No insider buying or selling signal is present, and there is no immediate cash impact. Consequently, the filing is considered neutral for investors.

Corporate Governance Expert

TL;DR: Standard equity-based compensation aligns director incentives; no red flags.

The four-quarter vesting schedule aligns director service with shareholder interests and includes a customary acceleration clause tied to the 2026 AGM. The size and terms are consistent with peer practices for small-cap biotech boards. There are no indications of unusual timing or preferential pricing. Governance impact is minimal and overall neutral.

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).

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^*

Fraser Claire

(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)

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

3. Date of Earliest Transaction (Month/Day/Year)
07/01/2025

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

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
Stock Option (right to buy)	$10.71	07/01/2025		A		6,452		(1)	07/01/2035	Common Stock	6,452	$0	6,452	D

Explanation of Responses:

1. The option vests and becomes exercisable in four equal quarterly installments occurring on October 1, 2025, January 1, 2026, April 1, 2026, and July 1, 2026, provided that if the issuer's 2026 annual meeting of stockholders occurs before July 1, 2026, the final quarterly vesting installment will vest on the day immediately prior to the date of such annual meeting, in each case, subject to the reporting person continuing in service on the Board as a non-employee director through the applicable vesting date.

	/s/ Thomas J. DesRosier, Attorney-in-Fact	07/02/2025
	** 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

How many Seres Therapeutics (MCRB) shares are covered by the new option grant?

The Form 4 shows an option covering 6,452 shares of common stock.

What is the exercise price of Claire Fraser’s stock option?

The option is exercisable at $10.71 per share.

When does the option granted on July 1 2025 start and finish vesting?

It vests in four equal quarterly installments on Oct 1 2025, Jan 1 2026, Apr 1 2026, and Jul 1 2026 (or earlier if the 2026 AGM occurs before Jul 1 2026).

Does the Form 4 report any open-market purchases or sales by the director?

No, the filing only reports the grant of a stock option; no purchases or sales of common shares are disclosed.

What is the expiration date of the option?

The option expires on July 1, 2035.