Seres Therapeutics, Inc. (MCRB) — Institutional Holders, Q2 2026
36 institutional investment managers reported a MCRB position on SEC Form 13F-HR for the quarter ended June 30, 2026, with a combined reported value of $17.9M. Every filer is listed below, ranked by position value. Put and call option positions are excluded, and a firm filing several lots or share classes is shown once with its total.
MCRB in Q2 2026: what funds did
Funds that filed a 13F for both Q1 2026 and Q2 2026, by what they did with the common stock. Share counts are adjusted for any split between the two quarters; dollar figures are the change in shares at this quarter’s price.
Biggest buyers
- MARSHALL WACE, LLPAdded · +32,706 sh+$258.1K
- XTX Topco LtdNew · +20,732 sh+$163.6K
- GOLDMAN SACHS GROUPNew · +15,229 sh+$120.2K
- CITADEL ADVISORSNew · +10,504 sh+$82.9K
- VANGUARD FIDUCIARYAdded · +9,042 sh+$71.3K
Biggest sellers
- SUSQUEHANNA INTERNATIONAL GROUP, LLPTrimmed · -47,011 sh-$370.9K
- AMERICAN CENTURY COMPANIESTrimmed · -34,003 sh-$268.3K
- TWO SIGMA INVESTMENTSSold out · -18,794 sh-$148.3K
- Vontobel Holding Ltd.Trimmed · -15,493 sh-$122.2K
- MORGAN STANLEYTrimmed · -9,562 sh-$75.4K
MCRB 13F holders ranked 1–36 of 36
| # | Institution | Shares | Value | % of portfolio | QoQShares vs Q1 2026 |
|---|---|---|---|---|---|
| 1 | Flagship Pioneering#1 · 1,155,850 sh | 1,155,850 | $9.1M | 0.59% | 0.0% |
| 2 | VANGUARD CAPITAL MANAGEMENT#2 · 287,776 sh | 287,776 | $2.3M | 0.00% | -2.2% |
| 3 | MARSHALL WACE, LLP#3 · 172,245 sh | 172,245 | $1.4M | <0.01% | +23.4% |
| 4 | Vontobel Holding Ltd.#4 · 122,975 sh | 122,975 | $970.3K | — | -11.2% |
| 5 | BlackRock#5 · 111,000 sh | 111,000 | $875.8K | 0.00% | +8.8% |
| 6 | GEODE CAPITAL MANAGEMENT#6 · 79,974 sh | 79,974 | $631.3K | 0.00% | +6.9% |
| 7 | SUSQUEHANNA INTERNATIONAL GROUP, LLP#7 · 58,328 sh | 58,328 | $460.2K | 0.00% | -44.6% |
| 8 | VANGUARD FIDUCIARY#8 · 48,685 sh | 48,685 | $384.1K | <0.01% | +22.8% |
| 9 | STATE STREET#9 · 33,901 sh | 33,901 | $267.5K | 0.00% | 0.0% |
| 10 | Lion Point Capital#10 · 31,570 sh | 31,570 | $249.1K | 1.19% | 0.0% |
| 11 | CHARLES SCHWAB INVESTMENT MANAGEMENT#11 · 31,049 sh | 31,049 | $245.0K | 0.00% | -1.8% |
| 12 | AMERICAN CENTURY COMPANIES#12 · 28,313 sh | 28,313 | $223.4K | <0.01% | -54.6% |
| 13 | XTX Topco Ltd#13 · 20,732 sh | 20,732 | $163.6K | <0.01% | New |
| 14 | GOLDMAN SACHS GROUP#14 · 15,229 sh | 15,229 | $120.2K | 0.00% | New |
| 15 | NORTHERN#15 · 14,765 sh | 14,765 | $116.5K | 0.00% | 0.0% |
| 16 | Invesco Ltd.#16 · 12,974 sh | 12,974 | $102.4K | 0.00% | -10.8% |
| 17 | MORGAN STANLEY#17 · 12,138 sh | 12,138 | $95.8K | 0.00% | -44.1% |
| 18 | CITADEL ADVISORS#18 · 10,504 sh | 10,504 | $82.9K | 0.00% | New |
| 19 | SIMPLEX TRADING#19 · 4,598 sh | 4,598 | $36.3K | 0.00% | +49.8% |
| 20 | SBI Securities , Ltd.#20 · 4,182 sh | 4,182 | $33.0K | — | +20.1% |
| 21 | Integrated Wealth Concepts#21 · 4,000 sh | 4,000 | $31.6K | <0.01% | New |
| 22 | GROUP ONE TRADING, L.P.#22 · 3,714 sh | 3,714 | $29.3K | 0.00% | +350.7% |
| 23 | JPMORGAN CHASE#23 · 3,636 sh | 3,636 | $28.3K | 0.00% | New |
| 24 | Vanguard Global Advisers#24 · 1,975 sh | 1,975 | $15.6K | 0.00% | 0.0% |
| 25 | FMR#25 · 1,528 sh | 1,528 | $12.1K | 0.00% | -12.8% |
| 26 | Rachor Investment Advisory Services#26 · 1,477 sh | 1,477 | $11.7K | <0.01% | 0.0% |
| 27 | UBS Group AG#27 · 484 sh | 484 | $3.8K | 0.00% | -93.1% |
| 28 | Tower Research Capital (TRC)#28 · 316 sh | 316 | $2.5K | <0.01% | -60.2% |
| 29 | BNP PARIBAS FINANCIAL MARKETS#29 · 211 sh | 211 | $1.7K | 0.00% | 0.0% |
| 30 | BARCLAYS PLC#30 · 167 sh | 167 | $1.3K | 0.00% | -97.4% |
| 31 | Continuum Advisory#31 · 47 sh | 47 | $371.00 | 0.00% | New |
| 32 | WELLS FARGO & COMPANY#32 · 10 sh | 10 | $79.00 | 0.00% | 0.0% |
| 33 | OSAIC#33 · 8 sh | 8 | $63.00 | 0.00% | 0.0% |
| 34 | Larson Financial Group#34 · 5 sh | 5 | $39.00 | 0.00% | New |
| 35 | WHITTIER OF NEVADA#35 · 1 sh | 1 | $8.00 | 0.00% | New |
| 36 | ROYAL BANK OF CANADA#36 · 11 sh | 11 | $0.00 | 0.00% | -89.7% |
Funds that sold out of MCRB in Q2 2026 (5)
Held MCRB at the end of Q1 2026 and filed a Q2 2026 13F without it. Not in the list above, because they no longer hold it. Largest prior position first.
| Institution | Shares sold | Value in Q1 2026 |
|---|---|---|
| TWO SIGMA INVESTMENTS18,794 sh | 18,794 | $166.7K |
| Physician Wealth Advisors142 sh | 142 | $1.3K |
| Sound Income Strategies8 sh | 8 | $71.00 |
| Allworth Financial4 sh | 4 | $36.00 |
| SRS Capital Advisors6 sh | 6 | $18.00 |
Source: Form 13F-HR filings on SEC EDGAR, Q2 2026. Values are as reported by each manager at quarter end. “% of portfolio” is the position’s share of the manager’s total reported 13F value for the same quarter. “New” means the manager filed a 13F for Q1 2026 without this position; a dash means no comparison is available. Where a manager’s own filing is internally inconsistent its value is withheld and it is listed last. 13F data shows reported holdings, not recommendations.