Seres TherapeuticsMCRB
13F holders, Q1 2026 (March 31)33holders −3
2new positions
7sold out
$8.87avg. 13F price*
At the end of Q1 2026, 33 institutions reported holding Seres Therapeutics Inc. (MCRB) in their 13F filings, down 3 from Q4 2025. 2 opened new positions and 7 sold out. The largest holders were Flagship Pioneering, LLC ($10.3M), Vanguard Capital Management LLC ($2.6M) and Marshall Wace, LLP ($1.2M).
- Company
- Seres Therapeutics Inc.
- CUSIP
- 81750R201
- Latest filing quarter
- Q2 2026
History
Number of 13F holders
Total Exit/New Position Q4 2025 → Q1 2026
| Institutions | Total Value | |
|---|---|---|
| New Positions | 2 | $14K |
| Exits | 7 | $2.3M |
All 13F filers, Q4 2025 → Q1 2026: 107,463 shares bought and 254,111 shares sold, net −146,648 shares. Counts holders who added, trimmed, opened or closed a position; split-adjusted.
Ownership 33 holders
| Flagship Pioneering, LLC | 0.88% | No change | 1,155,850 | $10.3M |
| Vanguard Capital Management LLC | 0.00% | — | 294,143 | $2.6M |
| Marshall Wace, LLP | 0.00% | Add +16.1% | 139,539 | $1.2M |
| Vontobel Holding Ltd. | 0.00% | Add +34.1% | 138,468 | $1.2M |
| Susquehanna International Group, LLP | 0.00% | Reduce -41.5% | 105,339 | $934K |
| BlackRock, Inc. | 0.00% | Reduce -1.5% | 102,026 | $905K |
| Geode Capital Management, LLC | 0.00% | Reduce -13.1% | 74,835 | $664K |
| American Century Companies Inc. | 0.00% | Add +283.0% | 62,316 | $553K |
| Vanguard Fiduciary Trust Co. | 0.00% | — | 39,643 | $352K |
| State Street Corp. | 0.00% | No change | 33,901 | $301K |
| Charles Schwab Investment Management Inc. | 0.00% | Add +0.8% | 31,630 | $281K |
| Lion Point Capital, LP | 1.67% | No change | 31,570 | $280K |
| Morgan Stanley | 0.00% | Reduce -13.6% | 21,700 | $192K |
| Two Sigma Investments, LP | 0.00% | Reduce -27.0% | 18,794 | $167K |
| Northern Trust Corp. | 0.00% | No change | 14,765 | $131K |
| Invesco Ltd. | 0.00% | Add +1.3% | 14,547 | $129K |
| UBS Group AG | 0.00% | Add +66.3% | 7,030 | $62K |
| Barclays PLC | 0.00% | Reduce -12.4% | 6,507 | $58K |
| SBI Securities Co., Ltd. | 0.00% | No change | 3,482 | $31K |
| Simplex Trading, LLC | 0.00% | Add +149.2% | 3,070 | $27K |
| Vanguard Global Advisers, LLC | 0.00% | — | 1,975 | $18K |
| FMR LLC | 0.00% | Add +0.7% | 1,752 | $16K |
| Rachor Investment Advisory Services, LLC | 0.01% | No change | 1,477 | $13K |
| Group One Trading LLC | 0.00% | New | 824 | $7K |
| Tower Research Capital LLC (TRC) | 0.00% | New | 794 | $7K |
| BNP Paribas Financial Markets | 0.00% | Reduce -72.7% | 211 | $2K |
| Physician Wealth Advisors, Inc. | 0.00% | No change | 142 | $1K |
| Royal Bank of Canada | 0.00% | Add +1088.9% | 107 | $1K |
| Wells Fargo & Company | 0.00% | Reduce -96.2% | 10 | $89 |
| Sound Income Strategies, LLC | 0.00% | No change | 8 | $71 |
| Osaic Holdings, Inc. | 0.00% | No change | 8 | $70 |
| Allworth Financial LP | 0.00% | No change | 4 | $36 |
| Arax Advisory Partners | 0.00% | Add +200.0% | 6 | $18 |
"% of holder's portfolio" is MCRB's weight in each manager's 13F, not the share of Seres Therapeutics Inc. the manager owns.