Form 8-K
8-K — Seres Therapeutics, Inc.
Accession: 0001193125-26-432004
Filed: 2026-10-26
Period: 2026-10-22
CIK: 0001609809
SIC: 2834 (PHARMACEUTICAL PREPARATIONS)
Item: Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers: Compensatory Arrangements of Certain Officers
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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
FORM 8-K
CURRENT REPORT
Pursuant to Section 13 or 15(d)
of the Securities Exchange Act of 1934
Date of Report (Date of earliest event reported): October 22, 2026
SERES THERAPEUTICS, INC.
(Exact name of Registrant as Specified in Its Charter)
Delaware
001-37465
27-4326290
(State or other jurisdiction
of incorporation)
(Commission
File Number)
(IRS Employer
Identification No.)
101 Cambridgepark Drive
Cambridge, MA
02140
(Address of principal executive offices)
(Zip Code)
Registrant’s telephone number, including area code: (617) 945-9626
(Former Name or Former Address, if Changed Since Last Report)
Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:
☐
Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
☐
Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
☐
Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
☐
Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))
Securities registered pursuant to Section 12(b) of the Act:
Title of each class
Trading
Symbol(s)
Name of each exchange
on which registered
Common stock, par value $0.001 per share
MCRB
The Nasdaq Stock Market LLC
(Nasdaq Global Select Market)
Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).
Emerging growth company ☐
If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐
Item 5.02.
Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.
On October 22, 2026, Marella Thorell, Executive Vice President and Chief Financial Officer of Seres Therapeutics, Inc. (the “Company”), resigned from her positions as Executive Vice President and Chief Financial Officer of the Company, effective November 15, 2026 (the “Effective Date”). Following the Effective Date, Ms. Thorell is expected to provide advisory services to the Company to support an orderly transition, on terms to be agreed between Ms. Thorell and the Company.
Forward-Looking Statements
This Current Report on Form 8-K contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this Current Report on Form 8-K that do not relate to matters of historical fact should be considered forward-looking statements, including statements about the expected transition services to be provided. These forward-looking statements are based on management’s current expectations. These statements are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements, including, but not limited to the factors discussed under the caption “Risk Factors” in our Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2026, and our other reports filed with the SEC could cause actual results to differ materially from those indicated by the forward-looking statements made in this Current Report on Form 8-K. Any such forward-looking statements represent management’s estimates as of the date of this Current Report on Form 8-K. While we may elect to update such forward-looking statements at some point in the future, we disclaim any obligation to do so, even if subsequent events cause our views to change. These forward-looking statements should not be relied upon as representing our views as of any date subsequent to the date of this Current Report on Form 8-K.
SIGNATURES
Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.
Date: October 26, 2026
SERES THERAPEUTICS, INC.
By:
/s/ Thomas J. DesRosier
Name:
Thomas J. DesRosier
Title:
Chief Legal Officer and Executive Vice President
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