Seres TherapeuticsMCRB
13F holders, Q2 2026 (June 30)35holders +2
7new positions
5sold out
1famous investor
$7.89avg. 13F price*
At the end of Q2 2026, 35 institutions reported holding Seres Therapeutics Inc. (MCRB) in their 13F filings, up 2 from Q1 2026. 7 opened new positions and 5 sold out. The largest holders were Flagship Pioneering, LLC ($9.1M), Vanguard Capital Management LLC ($2.3M) and Marshall Wace, LLP ($1.4M). One famous investor held it Ken Griffin (0.0% of Citadel Advisors's portfolio).
- Company
- Seres Therapeutics Inc.
- CUSIP
- 81750R201
- Latest filing quarter
- Q2 2026
History
Number of 13F holders
Total Exit/New Position Q1 2026 → Q2 2026
| Institutions | Total Value | |
|---|---|---|
| New Positions | 7 | $395K |
| Exits | 5 | $168K |
All 13F filers, Q1 2026 → Q2 2026: 111,133 shares bought and 147,228 shares sold, net −36,095 shares. Counts holders who added, trimmed, opened or closed a position; split-adjusted.
Ownership 35 holders
| Flagship Pioneering, LLC | 0.59% | No change | 1,155,850 | $9.1M |
| Vanguard Capital Management LLC | 0.00% | Reduce -2.2% | 287,776 | $2.3M |
| Marshall Wace, LLP | 0.00% | Add +23.4% | 172,245 | $1.4M |
| Vontobel Holding Ltd. | 0.00% | Reduce -11.2% | 122,975 | $970K |
| BlackRock, Inc. | 0.00% | Add +8.8% | 111,000 | $876K |
| Geode Capital Management, LLC | 0.00% | Add +6.9% | 79,974 | $631K |
| Susquehanna International Group, LLP | 0.00% | Reduce -44.6% | 58,328 | $460K |
| Vanguard Fiduciary Trust Co. | 0.00% | Add +22.8% | 48,685 | $384K |
| State Street Corp. | 0.00% | No change | 33,901 | $267K |
| Lion Point Capital, LP | 1.19% | No change | 31,570 | $249K |
| Charles Schwab Investment Management Inc. | 0.00% | Reduce -1.8% | 31,049 | $245K |
| American Century Companies Inc. | 0.00% | Reduce -54.6% | 28,313 | $223K |
| XTX Topco Ltd | 0.00% | New | 20,732 | $164K |
| Goldman Sachs Group Inc. | 0.00% | New | 15,229 | $120K |
| Northern Trust Corp. | 0.00% | No change | 14,765 | $116K |
| Invesco Ltd. | 0.00% | Reduce -10.8% | 12,974 | $102K |
| Morgan Stanley | 0.00% | Reduce -44.1% | 12,138 | $96K |
| Citadel Advisors | 0.00% | New | 10,504 | $83K |
| Simplex Trading, LLC | 0.00% | Add +49.8% | 4,598 | $36K |
| SBI Securities Co., Ltd. | 0.00% | Add +20.1% | 4,182 | $33K |
| Group One Trading LLC | 0.00% | Add +350.7% | 3,714 | $29K |
| JPMorgan Chase & Co. | 0.00% | New | 3,636 | $28K |
| Vanguard Global Advisers, LLC | 0.00% | No change | 1,975 | $16K |
| FMR LLC | 0.00% | Reduce -12.8% | 1,528 | $12K |
| Rachor Investment Advisory Services, LLC | 0.01% | No change | 1,477 | $12K |
| UBS Group AG | 0.00% | Reduce -93.1% | 484 | $4K |
| Tower Research Capital LLC (TRC) | 0.00% | Reduce -60.2% | 316 | $2K |
| BNP Paribas Financial Markets | 0.00% | No change | 211 | $2K |
| Barclays PLC | 0.00% | Reduce -97.4% | 167 | $1K |
| Continuum Advisory, LLC | 0.00% | New | 47 | $371 |
| Wells Fargo & Company | 0.00% | No change | 10 | $79 |
| Osaic Holdings, Inc. | 0.00% | No change | 8 | $63 |
| Larson Financial Group LLC | 0.00% | New | 5 | $39 |
| Whittier Trust Co. of Nevada Inc. | 0.00% | New | 1 | $8 |
| Royal Bank of Canada | 0.00% | Reduce -89.7% | 11 | $0 |
"% of holder's portfolio" is MCRB's weight in each manager's 13F, not the share of Seres Therapeutics Inc. the manager owns.