UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2025 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-37465 Seres Therapeutics, Inc. (Exact name of registrant as specified in its charter) FORM 10-Q (Mark One) (State or other jurisdiction of incor ...

Seres Therapeutics (NasdaqGS:MCRB) Q3 2025 Earnings Call November 05, 2025 08:30 AM ET Speaker4Good day, everyone, and thank you for standing by. My name is RG, and I will be your conference operator today. At this time, I would like to welcome everyone to the Q3 2025 Seres Therapeutics results and business updates. All lines have been placed on mute to prevent any background noise. After the speaker's remarks, there will be a question-and-answer session. If you would like to ask a question during this time ...

Exhibit 99.1 SERES THERAPEUTICS REPORTS THIRD QUARTER 2025 FINANCIAL RESULTS AND PROVIDES BUSINESS UPDATES Following constructive FDA feedback, Seres is finalizing its SER-155 Phase 2 study protocol for the prevention of bloodstream infections in adults undergoing allogeneic hematopoietic stem cell transplant for the treatment of hematological malignancies Ef orts are ongoing to obtain capital and other resources to support SER-155 Phase 2 study; pending securing funding, interim clinical results anticipate ...

Following constructive FDA feedback, Seres is finalizing its SER-155 Phase 2 study protocol for the prevention of bloodstream infections in adults undergoing allogeneic hematopoietic stem cell transplant for the treatment of hematological malignancies Efforts are ongoing to obtain capital and other resources to support SER-155 Phase 2 study; pending securing funding, interim clinical results anticipated within 12 months of study initiation Ongoing investigator-sponsored study in immune checkpoint related en ...

Core Insights - Seres Therapeutics, Inc. will host a conference call on November 5, 2025, at 8:30 a.m. ET to discuss Q3 2025 financial results and business updates [1][2] Company Overview - Seres Therapeutics is a clinical-stage company focused on improving patient outcomes in medically vulnerable populations through novel live biotherapeutics [3] - The company developed VOWST™, the first FDA-approved orally administered microbiome therapeutic, which was sold to Nestlé Health Science in September 2024 [3] - Seres is developing SER-155, which has received Breakthrough Therapy designation for reducing bloodstream infections in adults undergoing allo-HSCT and Fast Track designation for reducing infection risk and graft-versus-host disease in the same patient group [3] - SER-155 demonstrated a significant reduction in bloodstream infections and related complications compared to placebo in a Phase 1b clinical study [3] - The company plans to evaluate SER-155 and other cultivated live biotherapeutic candidates in various medically vulnerable populations, including autologous-HSCT patients, cancer patients with neutropenia, CAR-T recipients, and solid organ transplant recipients [3]

Core Insights - Seres Therapeutics has received up to $3.6 million in non-dilutive funding from CARB-X to support the development of an oral liquid formulation of SER-155, aimed at improving access for medically vulnerable patients, particularly those in intensive care who cannot take oral capsules [1][3][5] - SER-155 is being developed for patients undergoing allogeneic hematopoietic stem cell transplants (allo-HSCT) and has shown a 77% reduction in bacterial bloodstream infections (BSIs) compared to placebo in a Phase 1b study [2][5] - The development of a liquid formulation is expected to broaden the impact of SER-155 in additional high-risk patient populations susceptible to BSIs and antimicrobial resistant infections [3][5] Funding and Support - CARB-X, a global non-profit partnership, is providing funding to accelerate the development of antibacterial products, specifically targeting drug-resistant bacteria [1][4] - The funding is supported by various federal and international health organizations, including the U.S. Department of Health and Human Services and the UK Department of Health and Social Care [3][4] Clinical Development - SER-155 has received Breakthrough Therapy designation and Fast Track designation from the FDA, indicating its potential to significantly reduce the risk of infections in allo-HSCT patients [5][6] - The company is finalizing the clinical protocol for a well-powered, placebo-controlled Phase 2 study following positive feedback from the FDA [2][5] Company Background - Seres Therapeutics is focused on improving outcomes for medically vulnerable populations through live biotherapeutics and has previously developed VOWST™, the first FDA-approved orally administered microbiome therapeutic [5][6] - The company aims to evaluate SER-155 in various patient populations, including those undergoing autologous-HSCT, cancer patients with neutropenia, and patients in intensive care [6]

Core Insights - Seres Therapeutics, Inc. announced new post hoc data from its SER-155 Phase 1b trial, which will be presented at IDWeek 2025 [1] - SER-155 demonstrated a 77% reduction in bloodstream infections (BSIs) in patients undergoing allogeneic hematopoietic stem cell transplant (allo-HSCT) [3] - The company received positive FDA feedback for a Phase 2 study design of SER-155 and is finalizing the clinical protocol [4] Presentation Details - The presentation will cover clinical and microbiology outcomes of BSIs in adults undergoing allo-HCT, including differences in bacterial and fungal organisms between SER-155 and placebo groups [2] - The session is scheduled for October 20, 2025, at 10:30-10:42 am EDT [2] Company Background - Seres Therapeutics focuses on live biotherapeutics to improve outcomes in medically vulnerable populations [6] - The company developed VOWST™, the first FDA-approved orally administered microbiome therapeutic, sold to Nestlé Health Science in September 2024 [6] - SER-155 has received Breakthrough Therapy and Fast Track designations for its potential in reducing infections and complications in allo-HSCT patients [6]

Group 1 - Seres Therapeutics plans to reduce operating costs and cut its workforce by approximately 25% [1] - These measures, along with current operating plans, are expected to extend the company's cash runway into the second quarter of 2026 [1]

Core Insights - Seres Therapeutics is advancing its SER-155 Phase 2 study protocol for preventing bloodstream infections in adults undergoing allogeneic hematopoietic stem cell transplant, following positive feedback from the FDA [1][2][4] - The company is actively seeking capital to support the Phase 2 study and has implemented cost-reduction measures, including a 25% workforce reduction, to extend its cash runway into Q2 2026 [2][3][5] Company Developments - The SER-155 Phase 2 study is designed to be a placebo-controlled trial with approximately 248 participants, focusing on the prevention of bloodstream infections through 30 days post-transplant as the primary endpoint [4][7] - Interim clinical results are expected within 12 months of study initiation, which will facilitate timely engagement with the FDA regarding a potential Phase 3 study [4][7] - The company has received Breakthrough Therapy designation for SER-155, which has shown a 77% relative risk reduction in bloodstream infections in a prior Phase 1b study [7][8] Financial and Operational Strategy - The workforce reduction is expected to incur cash payments of approximately $1.0 to $1.4 million, primarily for severance costs, to be paid in Q4 2025 [5] - Cost-saving initiatives are anticipated to provide the company with additional opportunities to advance its strategic priorities and support its broader portfolio of product candidates [3][4]

Core Viewpoint - Seres Therapeutics (MCRB) has been upgraded to a Zacks Rank 2 (Buy), indicating a positive outlook on its earnings estimates, which is a significant factor influencing stock prices [1][4]. Earnings Estimates and Ratings - The Zacks rating system is based solely on a company's changing earnings picture, tracking the Zacks Consensus Estimate for EPS from sell-side analysts [2]. - The Zacks rating upgrade reflects an improvement in Seres Therapeutics' earnings outlook, which is expected to positively impact its stock price [4][6]. Impact of Earnings Estimate Revisions - Changes in a company's future earnings potential, as shown by earnings estimate revisions, are strongly correlated with near-term stock price movements [5]. - Institutional investors often adjust their valuations based on earnings estimates, leading to significant stock price movements [5]. Performance of Zacks Rank System - The Zacks Rank system classifies stocks into five groups based on earnings estimates, with a strong historical performance, particularly for Zacks Rank 1 stocks, which have averaged a +25% annual return since 1988 [8]. - The upgrade of Seres Therapeutics to Zacks Rank 2 places it in the top 20% of Zacks-covered stocks, indicating a strong potential for market-beating returns in the near term [10][11]. Recent Earnings Estimate Trends - For the fiscal year ending December 2025, Seres Therapeutics is expected to earn -$0.99 per share, unchanged from the previous year, but the Zacks Consensus Estimate has increased by 40.8% over the past three months [9].