Exhibit 99.1 SERES THERAPEUTICS REPORTS FIRST QUARTER 2024 FINANCIAL RESULTS AND PROVIDES BUSINESS UPDATES Continued market adoption of VOWST® with approximately 1,411 patient enrollment forms received, approximately 1,083 new patient starts, and net sales of $10.1 million during Q1 2024, and accelerated net sales in March and April SER-155 Phase 1b placebo-controlled Cohort 2 clinical readout expected end of Q3 2024 Further microbiome therapeutic candidates have potential to expand product franchise into a ...