Seres Therapeutics (MCRB) awards 56,250 stock options to officer

Rhea-AI Filing Summary

Seres Therapeutics, Inc. reported that officer Kelly Brady received a grant of stock options for 56,250 shares of common stock on March 4, 2026. The options have an exercise price of $9.13 per share and are held as a direct derivative position.

The option grant vests over time: 25% of the shares vest on March 2, 2027, with the remaining shares vesting in 12 equal quarterly installments after that date. This is a compensation-related award rather than an open-market stock purchase or sale.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Brady Kelly

Role See Remarks

Type	Security	Shares	Price	Value
Grant/Award	Stock Option (right to buy)	56,250	$0.00	--

Holdings After Transaction: Stock Option (right to buy) — 56,250 shares (Direct)

Footnotes (1)

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Form 4 Insider Transactions: What Each Field Means →

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
Estimated average burden
hours per response:			0.5

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^*

Brady Kelly

(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)
03/04/2026

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

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)	$9.13	03/04/2026		A		56,250		(1)	03/03/2036	Common Stock	56,250	$0	56,250	D

Explanation of Responses:

1. The option will vest as to 25% of the shares on March 2, 2027. The remainder of the shares will vest in 12 equal quarterly installments thereafter.

Remarks:

Chief Operating Officer, EVP

	/s/ Thomas J. DesRosier, Attorney-in-Fact for Kelly M. Brady	03/11/2026
	** 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 transaction did Seres Therapeutics (MCRB) report for Kelly Brady?

Seres Therapeutics reported a stock option grant to officer Kelly Brady for 56,250 shares. This derivative award gives the right to buy common stock at a fixed exercise price of $9.13 per share.

How many Seres Therapeutics (MCRB) options were granted and at what price?

Kelly Brady received stock options covering 56,250 shares of Seres Therapeutics common stock. The options carry an exercise price of $9.13 per share, meaning that is the price required to purchase each share upon exercise.

What is the vesting schedule for Kelly Brady’s Seres Therapeutics (MCRB) option grant?

The option will vest 25% on March 2, 2027. The remaining 75% will then vest in 12 equal quarterly installments, creating a multi-year vesting period that links continued service to full option ownership.

Does this Seres Therapeutics (MCRB) Form 4 show a stock purchase or sale?

The Form 4 shows a stock option grant, not an open-market trade. It records the award of the right to buy 56,250 shares at $9.13, rather than any immediate purchase or sale of common stock.

How many Seres Therapeutics (MCRB) options does Kelly Brady hold after this grant?

After this transaction, Kelly Brady is shown holding 56,250 stock options in Seres Therapeutics. These options relate to the same 56,250 underlying common shares and become exercisable according to the stated vesting schedule.