Seres Therapeutics, Inc.: directors' dealings · United States · SEC (Form 4)

About Seres Therapeutics, Inc.

Seres Therapeutics, Inc. (NASDAQ: MCRB) is a U.S.-listed biotechnology company traded on the NASDAQ market in the United States. Headquartered in Cambridge, Massachusetts, Seres focuses on a highly specialized corner of healthcare: live biotherapeutics designed to modulate the human microbiome and address serious diseases with significant unmet medical need. The company was founded in 2010 and built its reputation on a scientific platform centered on rationally selected bacterial consortia. Its team also helped pioneer the development and FDA approval of VOWST™, the first oral live biotherapeutic, which was sold to Nestlé Health Science in September 2024. Following that strategic divestiture, Seres has narrowed its focus to research and development, with SER-155 as its lead program. SER-155 is being developed to prevent bloodstream infections in adults undergoing allogeneic hematopoietic stem cell transplant (allo-HSCT), a clinically important setting with high infection risk and substantial unmet need. The company has disclosed that SER-155 has received Breakthrough Therapy designation for reducing bloodstream infections in this population, as well as Fast Track designation for reducing infection risk and graft-versus-host disease risk. In 2025, Seres reported encouraging clinical and translational biomarker data from its Phase 1b study, outlined preparations for a Phase 2 protocol, and said it had received constructive FDA feedback, while also noting that additional capital would be required to advance the program. From a competitive standpoint, Seres operates in a scientifically demanding niche where differentiation depends on platform credibility, clinical execution, and regulatory progress. The company presents itself as a leader in microbiome therapeutics, but it remains small relative to large-cap pharmaceutical groups. Its geographic footprint is concentrated in Cambridge, Massachusetts, with core research, development, and operating activities based in the United States. Recent notable developments include the VOWST™ sale, the strategic refocus on SER-155, active partnership and financing discussions, and governance changes in July 2025, when CEO Eric Shaff departed and interim co-CEOs were appointed. For investors, Seres Therapeutics remains a high-risk, high-optional biotech story: scientifically differentiated, but still highly dependent on clinical success, funding access, and regulatory execution.