Seres Therapeutics, Inc.
MCRB · Pharmaceutical Preparations · 9.6M shares · -57%/yr ↓ buyback · EDGAR filings ↗
Net buyback after stock comp: -$34M (gross $33K, SBC $34M)
Reference price $7.53 · est. market cap ~$72M — last insider sale, 2026-05-18 (estimated from the dated SEC Form 4 price × shares outstanding — not a live quote)
Grade
D46Flattering headline profitability is a one-off artifact of the VOWST/Nestlé asset sale, while the underlying clinical-stage business carries explicit going-concern doubt.
Strengths
- Net margin (99th pct), ROA (89th pct) and positive FCF (80th pct) — but driven entirely by the VOWST divestiture gain, not operations
- SER-155 holds Breakthrough/Fast Track designation with a strong Phase 1b BSI signal
Risks
- Explicit substantial-doubt going-concern; filing references possible Bankruptcy Code relief or wind-down
- Operating margin -119% (9th pct); only $45.8M cash and SER-155 Phase 2 paused for lack of funding
- Positive Phase 3 readouts (SER-109) belong to an already-divested asset, not the remaining pipeline
Notable findings
- Going concernThe principal risks and uncertainties affecting our business include the following: • We have identified conditions and events that raise substantial doubt regarding our ability to continue as a go
- Exec changeRecent 8-K item 5.02 8-K ↗
- Fund exitedNotable fund(s) exited this quarter: VANGUARD GROUP INC, GOLDMAN SACHS GROUP INC
- Buying back stockNet buyback — share count -57%/yr over 3y
- Notable holderHeld by 3 notable fund(s): CITADEL ADVISORS LLC, STATE STREET CORP, FMR LLC (as of 2026-03-31)
- Insider sellingInsider selling — 8 open-market sale(s) by 5 insider(s) (cluster of 5 insiders, last 6mo) Form 4 ↗
Quarterly revenue
Last 4 quarters · from SEC filings.
Key metrics
Operating margin
-11910.1%
Net margin
721.9%
Return on equity
12.9%
Return on assets
4.1%
Current ratio
2.6×
Free cash flow
$865K
EBITDA
-$90M
Tangible book value
$44M
Cash & investments
$46M
Stock comp / revenue
1373.9%
Insider transactions · last 18 months
| Date | Insider | Type | Shares | Price |
|---|---|---|---|---|
| 2026-05-18 | Shaff Eric D. | Sell | 259 | $7.53 |
| 2026-05-18 | Brady Kelly | Sell | 59 | $7.53 |
| 2026-05-18 | Henn Matthew R | Sell | 77 | $7.53 |
| 2026-05-18 | DesRosier Thomas | Sell | 79 | $7.53 |
| 2026-05-15 | Shaff Eric D. | Option exercise | 722 | — |
| 2026-05-15 | DesRosier Thomas | Option exercise | 244 | — |
| 2026-05-15 | Henn Matthew R | Option exercise | 238 | — |
| 2026-05-15 | Brady Kelly | Option exercise | 180 | — |
| 2026-02-15 | Young Teresa L. | Option exercise | 231 | — |
| 2026-02-15 | Young Teresa L. | Sell | 75 | $8.47 |
| 2026-02-15 | Shaff Eric D. | Option exercise | 723 | — |
| 2026-02-15 | Shaff Eric D. | Sell | 259 | $8.47 |
| 2026-02-15 | DesRosier Thomas | Option exercise | 244 | — |
| 2026-02-15 | DesRosier Thomas | Sell | 78 | $8.47 |
| 2026-02-15 | Henn Matthew R | Option exercise | 239 | — |
| 2026-02-15 | Henn Matthew R | Sell | 89 | $8.47 |
| 2025-11-15 | DesRosier Thomas | Option exercise | 132 | — |
| 2025-11-15 | DesRosier Thomas | Option exercise | 112 | — |
| 2025-11-15 | DesRosier Thomas | Sell | 76 | $17.30 |
| 2025-11-15 | Young Teresa L. | Option exercise | 4.0K | — |
| 2025-11-15 | Young Teresa L. | Option exercise | 132 | — |
| 2025-11-15 | Young Teresa L. | Option exercise | 98 | — |
| 2025-11-15 | Young Teresa L. | Sell | 1.0K | $17.30 |
| 2025-11-15 | Shaff Eric D. | Option exercise | 390 | — |
| 2025-11-15 | Shaff Eric D. | Option exercise | 331 | — |
| 2025-11-15 | Shaff Eric D. | Sell | 217 | $17.30 |
| 2025-11-15 | Henn Matthew R | Option exercise | 4.0K | — |
| 2025-11-15 | Henn Matthew R | Option exercise | 140 | — |
| 2025-11-15 | Henn Matthew R | Option exercise | 98 | — |
| 2025-11-15 | Henn Matthew R | Sell | 1.3K | $17.30 |
| 2025-08-18 | Shaff Eric D. | Sell | 217 | $16.65 |
| 2025-08-18 | Young Teresa L. | Sell | 59 | $16.65 |
| 2025-08-18 | DesRosier Thomas | Sell | 76 | $16.65 |
| 2025-08-18 | Henn Matthew R | Sell | 73 | $16.65 |
| 2025-08-15 | Young Teresa L. | Option exercise | 97 | — |
| 2025-08-15 | DesRosier Thomas | Option exercise | 133 | — |
| 2025-08-15 | DesRosier Thomas | Option exercise | 111 | — |
| 2025-08-15 | Young Teresa L. | Option exercise | 133 | — |
| 2025-08-15 | Shaff Eric D. | Option exercise | 391 | — |
| 2025-08-15 | Shaff Eric D. | Option exercise | 333 | — |
| 2025-08-15 | Henn Matthew R | Option exercise | 141 | — |
| 2025-08-15 | Henn Matthew R | Option exercise | 97 | — |
| 2025-05-16 | Shaff Eric D. | Sell | 220 | $7.28 |
| 2025-05-16 | Young Teresa L. | Sell | 63 | $7.28 |
| 2025-05-16 | Henn Matthew R | Sell | 77 | $7.28 |
| 2025-05-15 | Shaff Eric D. | Option exercise | 331 | — |
| 2025-05-15 | Young Teresa L. | Option exercise | 133 | — |
| 2025-05-15 | DesRosier Thomas | Option exercise | 111 | — |
| 2025-05-15 | DesRosier Thomas | Sell | 79 | $7.28 |
| 2025-05-15 | Henn Matthew R | Option exercise | 140 | — |
| 2025-05-15 | Henn Matthew R | Option exercise | 98 | — |
| 2025-05-15 | DesRosier Thomas | Option exercise | 133 | — |
| 2025-05-15 | Young Teresa L. | Option exercise | 98 | — |
| 2025-05-15 | Shaff Eric D. | Option exercise | 390 | — |
| 2025-02-18 | von Moltke Lisa | Sell | 4.4K | $0.81 |
| 2025-02-18 | Young Teresa L. | Sell | 3.3K | $0.81 |
| 2025-02-18 | Henn Matthew R. | Sell | 4.0K | $0.81 |
| 2025-02-18 | Shaff Eric D. | Sell | 13K | $0.81 |
| 2025-02-18 | DesRosier Thomas | Sell | 4.3K | $0.81 |
| 2025-02-15 | von Moltke Lisa | Option exercise | 3.0K | — |
| 2025-02-15 | Shaff Eric D. | Option exercise | 7.8K | — |
| 2025-02-15 | Shaff Eric D. | Option exercise | 27K | — |
| 2025-02-15 | von Moltke Lisa | Option exercise | 8.9K | — |
| 2025-02-15 | DesRosier Thomas | Option exercise | 2.7K | — |
| 2025-02-15 | DesRosier Thomas | Option exercise | 8.9K | — |
| 2025-02-15 | Young Teresa L. | Option exercise | 7.8K | — |
| 2025-02-15 | Young Teresa L. | Option exercise | 2.7K | — |
| 2025-02-15 | Henn Matthew R. | Option exercise | 2.8K | — |
| 2025-02-15 | Henn Matthew R. | Option exercise | 7.8K | — |
All non-derivative Form 4 activity (SEC), newest first.
Clinical trials
| Trial | Title | Phase | Status | Primary completion |
|---|---|---|---|---|
| NCT04995653 ↗ | A Multiple Dose Study to Evaluate Safety, Tolerability, PK, and Efficacy of SER-155 in Adults Undergoing HSCT Allogeneic Hematopoietic Stem Cell Transplantation | PHASE1 | Completed | 2024-07-23 |
| NCT03183141 ↗ | ECOSPOR IV: An Open-Label Study Evaluating SER-109 in Recurrent Clostridioides Difficile Infection Clostridioides Difficile Infection | PHASE3 | Completed | 2022-04-29 |
| NCT03759041 ↗ | A Study to Assess Efficacy and Safety of SER-287 in Adults With Active Mild-to-Moderate Ulcerative Colitis Ulcerative Colitis | PHASE2 | Terminated | 2021-05-28 |
| NCT03183128 ↗ | ECOSPOR III - SER-109 Versus Placebo in the Treatment of Adults With Recurrent Clostridium Difficile Infection Clostridium Difficile Infection | PHASE3 | Completed | 2020-07-03 |
| NCT02830542 ↗ | SER-262 Versus Placebo in Adults With Primary Clostridium Difficile Infection to Prevent Recurrence Clostridium Difficile Infection | PHASE1 | Completed | 2018-05-01 |
| NCT02618187 ↗ | A Study to Evaluate the Safety, Tolerability and Microbiome Dynamics of SER-287 in Subjects With Mild-to-Moderate Ulcerative Colitis Ulcerative Colitis | PHASE1 | Completed | 2017-12-06 |
| NCT02437487 ↗ | SER-109 Versus Placebo to Prevent Recurrent Clostridium Difficile Infection (RCDI) Clostridium Difficile | PHASE2 | Completed | 2016-07-01 |
| NCT02437500 ↗ | Expanded Access Program of SER-109 in the Treatment of Adults With Recurrent Clostridioides Difficile Infection (RCDI) Clostridioides Difficile Infection | — | Approved For Marketing |
Source: ClinicalTrials.gov (U.S. NIH) · active studies first.
Notable events (8-K)
| Date | Items | |
|---|---|---|
| 2026-06-05 | Material agreementReg FDExhibits | filing ↗ |
| 2026-06-01 | Exec/director change | filing ↗ |
| 2026-05-05 | ResultsExhibits | filing ↗ |
| 2026-03-16 | Other | filing ↗ |
| 2026-03-12 | ResultsReg FDExhibits | filing ↗ |
| 2026-03-02 | Exec/director changeExhibits | filing ↗ |
| 2025-11-05 | ResultsReg FDExhibits | filing ↗ |
| 2025-10-03 | Other | filing ↗ |
Recent filings
| Form | Filed | Period | Accession |
|---|---|---|---|
| 8-K | 2026-06-05 | 2026-06-02 | 0001193125-26-258366 ↗ |
| 8-K | 2026-06-01 | 2026-05-30 | 0001193125-26-251548 ↗ |
| 10-Q | 2026-05-05 | 2026-03-31 | 0001193125-26-205434 ↗ |
| 8-K | 2026-05-05 | 2026-05-05 | 0001193125-26-205009 ↗ |
| 8-K | 2026-03-16 | 2026-03-16 | 0001193125-26-108482 ↗ |
| 8-K | 2026-03-12 | 2026-03-12 | 0001193125-26-103034 ↗ |
| 10-K | 2026-03-12 | 2025-12-31 | 0001193125-26-103276 ↗ |
| 8-K | 2026-03-02 | 2026-02-27 | 0001193125-26-085368 ↗ |
| 8-K | 2025-11-05 | 2025-11-05 | 0001193125-25-265708 ↗ |
| 10-Q | 2025-11-05 | 2025-09-30 | 0001193125-25-266011 ↗ |
| 8-K | 2025-10-03 | 2025-09-23 | 0001193125-25-230118 ↗ |
| 10-Q | 2025-08-06 | 2025-06-30 | 0000950170-25-103611 ↗ |