Teresa L. Young - 15 Feb 2026 Form 4 Insider Report for Seres Therapeutics, Inc. (MCRB)

Reporting relationship: EVP, Chief Commercial & Strategy Officer
Issuer ticker: MCRB
Reported as of: 15 Feb 2026
Net transaction value: -$635
SEC form: 4
Accepted by SEC: 18 Feb 2026, 16:30:10 UTC
Prior SEC filing: 18 Nov 2025
Source filing: View source filing
Reporting owner signature: /s/ Thomas J. DesRosier, attorney-in-fact for Teresa L. Young

Key filing fact

Teresa L. Young filed Form 4 for Seres Therapeutics, Inc. (MCRB) on 18 Feb 2026.

Key facts

This page summarizes Teresa L. Young's Form 4 filing for Seres Therapeutics, Inc. (MCRB).
4 reported transactions and 2 derivative rows are listed below.
Accepted by SEC: 18 Feb 2026, 16:30.

Change

Previous filing in this sequence was filed on 18 Nov 2025.
Current net transaction value: -$635.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001814656 Primary reporting owner

Young Teresa L.

Relationship: EVP, Chief Commercial & Strategy Officer
Address: C/O SERES THERAPEUTICS, INC., 101 CAMBRIDGE PARK DRIVE, CAMBRIDGE
Signature: /s/ Thomas J. DesRosier, attorney-in-fact for Teresa L. Young
Signature date: 18 Feb 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

MCRB transaction

Common Stock

Options Exercise

Transaction value
Shares: +231
Change %: +2.7%
Price
Shares after: 8,632
Date: 15 Feb 2026
Ownership: Direct
Footnotes: F1

MCRB transaction

Common Stock

Sale

Transaction value: $635
Shares: -75
Change %: -0.87%
Price: $8.47
Shares after: 8,557
Date: 15 Feb 2026
Ownership: Direct
Footnotes: F2

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

MCRB transaction Derivative

Restricted Stock Units

Options Exercise

Transaction value: $0
Shares: -133
Change %: -20%
Price: $0.000000
Shares after: 531
Date: 15 Feb 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 133
Exercise price
Footnotes: F1, F3

MCRB transaction Derivative

Restricted Stock Units

Options Exercise

Transaction value: $0
Shares: -98
Change %: -11%
Price: $0.000000
Shares after: 780
Date: 15 Feb 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 98
Exercise price
Footnotes: F1, F4

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Rule 10b5-1 trading plan

These transactions were reported as open-market trades under a Rule 10b5-1 plan. The plan lets an insider set trading instructions in advance, which can reduce the risk of trading while in possession of material nonpublic information.

Original filing language: transaction made pursuant to a contract, instruction, or written plan intended to satisfy Rule 10b5-1(c).

Explanation of responses 4 footnotes

Footnote F1

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

Footnote F2

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 instruction adopted by the reporting person on March 5, 2023, solely with the intent to cover taxes in connection with the vesting of the restricted stock units.

Footnote F3

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.

Footnote F4

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.

SEC remarks

EVP, Chief Commercial & Strategy Officer