Seres Therapeutics, Inc. filed a Form 8-K on October 26, 2026, disclosing that Executive Vice President and Chief Financial Officer Marella Thorell resigned from her positions effective November 15, 2026.

Key Highlights

  • Resignation submitted: Marella Thorell notified the company of her resignation on October 22, 2026.
  • Effective date: The resignation takes effect November 15, 2026.
  • Role vacated: Ms. Thorell held the titles of Executive Vice President and Chief Financial Officer.
  • Transition support: Following the effective date, Ms. Thorell is expected to provide advisory services to support an orderly transition, on terms to be agreed between her and the company.
  • Exchange listing: Seres Therapeutics common stock trades on NASDAQ:MCRB.

Marella Thorell's Departure from Seres Therapeutics CFO Role

According to the filing, Marella Thorell resigned from her positions as Executive Vice President and Chief Financial Officer of Seres Therapeutics, Inc. on October 22, 2026. The company disclosed that her resignation becomes effective on November 15, 2026, which the filing designates as the "Effective Date."

The filing further disclosed that 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." No successor CFO was named in the filing, and no specific terms of the advisory arrangement were provided. The 8-K was signed on behalf of the company by Thomas J. DesRosier, Chief Legal Officer and Executive Vice President.

The company noted that statements regarding the expected transition services constitute forward-looking statements under the Private Securities Litigation Reform Act of 1995, and the filing cautions that actual outcomes may differ materially from those expressed in such statements. The filing directs readers to risk factors discussed in the company's Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2026.

What Was Disclosed

Seres Therapeutics reported the resignation of CFO and EVP Marella Thorell, effective November 15, 2026, with post-departure advisory services anticipated on terms still to be agreed. No replacement was announced in this filing.