Seres Therapeutics grants 7,500 stock options to officer

Seres Therapeutics, Inc. reported that company officer Marella Thorell received a compensatory grant of stock options covering 7,500 shares of common stock at an exercise price of $9.13 per share.

Rhea-AI Filing Summary

Seres Therapeutics, Inc. reported that company officer Marella Thorell received a compensatory grant of stock options covering 7,500 shares of common stock at an exercise price of $9.13 per share. The options were awarded at no cost and will vest as to 25% of the shares on March 2, 2027, with the remaining shares vesting in 12 equal quarterly installments thereafter, subject to continued service.

Insights

Equity compensation analyst

Routine stock option grant to a Seres Therapeutics officer as part of compensation.

Seres Therapeutics granted Marella Thorell stock options for 7,500 shares of common stock at an exercise price of $9.13 per share. The grant was recorded as an acquisition under a compensation-related award, not an open-market purchase.

The options vest over time: 25% of the shares on March 2, 2027, with the balance vesting in 12 equal quarterly installments thereafter. This long vesting schedule ties a portion of the officer’s potential upside to ongoing service and future company performance, which is typical for equity incentives.

Insider Trade Summary

Grant/Award: 7,500 shares

Grant/Award 1 txn

Insider Thorell Marella

Role See Remarks

Type	Security	Shares	Price	Value
Grant/Award	Stock Option (right to buy) F1	7,500	$0.00	$0.00

Holdings After Transaction: Stock Option (right to buy) — 7,500 contracts (Direct)

Footnotes (1)

1. F1. 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.

Key Figures

Options granted: 7,500 shares Exercise price: $9.13 per share Post-transaction derivative holdings: 7,500 options +3 more

6 metrics

Options granted 7,500 shares Stock options on common stock granted to Marella Thorell

Exercise price $9.13 per share Conversion or exercise price of the granted stock options

Post-transaction derivative holdings 7,500 options Total derivative securities beneficially owned after the transaction

Vesting cliff 25% on March 2, 2027 Initial vesting tranche of the stock option award

Remaining vesting schedule 12 equal quarterly installments Vesting pattern for remaining option shares after March 2, 2027

Option expiration March 3, 2036 Expiration date of the stock option award

Key Terms

stock option, exercise price, vesting, derivative securities

4 terms

stock option financial

"The option will vest as to 25% of the shares on March 2, 2027."

A stock option is a contract that gives you the right to buy or sell a company's stock at a specific price within a certain time frame. People use them to potentially make money if the stock's price moves favorably or to protect against losses. It's like holding a coupon that can be used to buy or sell stock at a set price later on.

exercise price financial

"conversion_or_exercise_price": "9.1300""

The exercise price is the fixed amount at which you can buy or sell an asset, like a stock, when using an options contract. It matters because it helps determine whether exercising the option will be profitable or not, depending on the current market price. Think of it as the set price you agree on today to buy or sell later.

vesting financial

"The option will vest as to 25% of the shares on March 2, 2027."

Vesting is the process by which you earn full ownership of something, like company stock or a retirement benefit, over time. It’s like earning the right to keep a gift piece by piece the longer you stay with a company, making sure employees stay committed before they receive all the benefits.

derivative securities financial

"total_shares_following_transaction": "7500.0000""

Financial contracts whose value is tied to the price or performance of another asset, such as a stock, bond, commodity, index, or currency; examples include options, futures and swaps. They matter to investors because they let you protect against price swings, bet on future moves or gain larger exposure with less upfront cash—like using a lever or insurance policy on an investment—so they can amplify gains and losses and help manage portfolio risk.

FAQ

What did Marella Thorell report on the Form 4 for Seres Therapeutics (MCRB)?

Marella Thorell reported a grant of stock options for 7,500 shares of Seres Therapeutics common stock at an exercise price of $9.13 per share, received as equity compensation rather than an open-market purchase.

How many Seres Therapeutics (MCRB) options did Marella Thorell receive and at what price?

Marella Thorell received stock options on 7,500 shares of Seres Therapeutics common stock with an exercise price of $9.13 per share, according to the Form 4.

When do Marella Thorell’s Seres Therapeutics (MCRB) options vest?

The options will vest as to 25% of the shares on March 2, 2027. The remaining shares vest in 12 equal quarterly installments thereafter, contingent on continued service.

Is Marella Thorell’s Seres Therapeutics (MCRB) Form 4 a market purchase or a grant?

The Form 4 reflects a grant or award acquisition of stock options, not a market purchase. The transaction is coded as an A (grant, award, or other acquisition) with an exercise price of $9.13 per share.

How many Seres Therapeutics (MCRB) derivative securities does Marella Thorell hold after this transaction?

Following this grant, Marella Thorell holds 7,500 stock options related to Seres Therapeutics common stock, as indicated by the total derivative securities beneficially owned after the reported transaction.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 07/10/2026 - 04:15 PM Accepted by SEC EDGAR 07/10/2026 - 04:15 PM Learn about SEC filing dates

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^*

Thorell Marella

(Last) (First) (Middle)

C/O SERES THERAPEUTICS, INC.

101 CAMBRIDGE PARK DRIVE

(Street)

CAMBRIDGE MASSACHUSETTS 02140

(City) (State) (Zip)

UNITED STATES

(Country)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
07/08/2026

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

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

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

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	07/08/2026		A		7,500		(1)	03/03/2036	Common Stock	7,500	$0	7,500	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:

EVP and Chief Financial Officer

	/s/ Thomas J. DesRosier, Attorney-in-Fact for Marella Thorell	07/10/2026
	** 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.
* Form 4: SEC 1474 (03-26)