Marella Thorell is leaving her role as Chief Financial Officer and Executive Vice President at Seres Therapeutics, Inc. The company disclosed the departure in a Form 8-K filed with the Securities and Exchange Commission on October 22, 2026. Thorell's resignation becomes effective on November 15, 2026.
Following that effective date, Thorell is expected to provide advisory services to Seres Therapeutics to support an orderly transition. The specific terms of this arrangement are to be agreed upon between Thorell and the company. The filing identifies the company's principal executive offices as located at 101 Cambridgepark Drive in Cambridge, Massachusetts.
Seres Therapeutics, Inc. is a Delaware corporation with a Commission File Number of 001-37465 and an IRS Employer Identification Number of 27-4326290. Its common stock, which has a par value of $0.001 per share, trades under the symbol MCRB on the Nasdaq Global Select Market. The company did not check the box indicating it is an emerging growth company as defined in Rule 405 of the Securities Act of 1934 or Rule 12b-2 of the Securities Exchange Act of 1934.
The Form 8-K was signed by Thomas J. DesRosier, who serves as Chief Legal Officer and Executive Vice President at Seres Therapeutics. The signature date on the document is October 26, 2026, although the date of the earliest event reported is listed as October 22, 2026.
The filing includes a section on forward-looking statements, noting that any statements regarding expected transition services are based on management's current expectations. Seres Therapeutics stated that these statements involve known and unknown risks and uncertainties that could cause actual results to differ materially from those expressed. The company referenced risk factors discussed in its Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2026, and other reports filed with the SEC.