MCRB Institutional Ownership & Shareholders
SERES THERAPEUTICS INC (MCRB) is currently held by 35 institutional investors tracked by InsiderSet, with a combined reported market value of approximately $17.35M based on the latest available SEC Form 13F filings for the quarter ended June 30, 2026.
Flagship Pioneering, Llc is currently the largest disclosed institutional shareholder of MCRB tracked by InsiderSet, reporting ownership valued at approximately $9.12M in its June 30, 2026 SEC Form 13F filing. Based on current market prices and the latest disclosed share count, the position is now estimated to be worth approximately $2.12M, representing an estimated loss of -76.81% since the filing period.
The top 10 institutional shareholders tracked on this page collectively account for approximately 92% of the total disclosed MCRB value among the investors covered in this analysis. Major shareholders include Flagship Pioneering, Llc, Vanguard Capital Management Llc, Marshall Wace, Llp, and several other long-term asset managers with concentrated positions in SERES THERAPEUTICS INC (MCRB).
This page ranks the largest institutional MCRB shareholders using publicly disclosed SEC Form 13F data, including reported values, estimated current holding values, portfolio allocation percentages, ownership concentration metrics, and historical holding changes across major hedge funds and investment firms.
Institutional Holders
35
Total Reported Value
$17.35M
Largest Holder
Flagship Pioneering, Llc
Largest Position
$9.12M
Insider Transactions (90d)
16
Latest Filing Quarter
Q2 2026
New Institutional Positions
49
Funds Exiting Positions
0
| Name | Investor/Manager | Portfolio % | Quantity | Reported Balance | Current Estimated Value | Gain/loss Since Filing | Estimated Portfolio Performance |
|---|---|---|---|---|---|---|---|
| Flagship Pioneering, Llc | 0.59% | 1,155,850 | $9,119,658 | $2,115,206 | -$7,004,453 | -76.81% | |
| Vanguard Capital Management Llc | 0.00% | 287,776 | $2,270,553 | $526,630 | -$1,743,923 | -76.81% | |
| Marshall Wace, Llp | 0.00% | 172,245 | $1,359,016 | $315,208 | -$1,043,808 | -76.81% | |
| Blackrock, Inc. | 0.00% | 111,000 | $875,790 | $203,130 | -$672,660 | -76.81% | |
| Geode Capital Management, Llc | 0.00% | 79,974 | $631,301 | $146,352 | -$484,949 | -76.82% | |
| Susquehanna International Group, Llp | 0.00% | 58,328 | $460,208 | $106,740 | -$353,468 | -76.81% | |
| Vanguard Fiduciary Trust Co | 0.00% | 48,685 | $384,125 | $89,094 | -$295,031 | -76.81% | |
| Vontobel Holding Ltd. | 0.00% | 114,566 | $383,796 | $209,656 | -$174,140 | -45.37% | |
| State Street Corp | 0.00% | 33,901 | $267,479 | $62,039 | -$205,440 | -76.81% | |
| Lion Point Capital, Lp | 1.19% | 31,570 | $249,087 | $57,773 | -$191,314 | -76.81% | |
| Charles Schwab Investment Management Inc | 0.00% | 31,049 | $244,977 | $56,820 | -$188,157 | -76.81% | |
| American Century Companies Inc | 0.00% | 28,313 | $223,390 | $51,813 | -$171,577 | -76.81% | |
| Xtx Topco Ltd | 0.00% | 20,732 | $163,575 | $37,940 | -$125,635 | -76.81% | |
| Goldman Sachs Group Inc | 0.00% | 15,229 | $120,157 | $27,869 | -$92,288 | -76.81% | |
| Northern Trust Corp | 0.00% | 14,765 | $116,496 | $27,020 | -$89,476 | -76.81% | |
| Invesco Ltd. | 0.00% | 12,974 | $102,365 | $23,742 | -$78,623 | -76.81% | |
| Morgan Stanley | 0.00% | 12,138 | $95,769 | $22,213 | -$73,556 | -76.81% | |
| Citadel Advisors Llc | 0.00% | 10,504 | $82,877 | $19,222 | -$63,655 | -76.81% | |
| J. Safra Sarasin Holding Ag | 0.00% | 14,997 | $50,240 | $27,445 | -$22,795 | -45.37% | |
| Simplex Trading, Llc | 0.00% | 4,598 | $36,278 | $8,414 | -$27,864 | -76.81% | |
| Group One Trading Llc | 0.00% | 3,714 | $29,303 | $6,797 | -$22,506 | -76.81% | |
| Jpmorgan Chase & Co | 0.00% | 3,636 | $28,325 | $6,654 | -$21,671 | -76.51% | |
| Vanguard Global Advisers, Llc | 0.00% | 1,975 | $15,583 | $3,614 | -$11,969 | -76.81% | |
| Sbi Securities Co., Ltd. | 0.00% | 3,601 | $12,063 | $6,590 | -$5,473 | -45.37% | |
| Fmr Llc | 0.00% | 1,528 | $12,056 | $2,796 | -$9,260 | -76.81% | |
| Rachor Investment Advisory Services, Llc | 0.00% | 1,185 | $3,970 | $2,169 | -$1,801 | -45.38% | |
| Ubs Group Ag | 0.00% | 484 | $3,818 | $886 | -$2,932 | -76.80% | |
| Tower Research Capital Llc (Trc) | 0.00% | 316 | $2,493 | $578 | -$1,915 | -76.80% | |
| Bnp Paribas Financial Markets | 0.00% | 211 | $1,665 | $386 | -$1,279 | -76.81% | |
| Barclays Plc | 0.00% | 167 | $1,318 | $306 | -$1,012 | -76.81% | |
| Continuum Advisory, Llc | 0.00% | 47 | $371 | $86 | -$285 | -76.82% | |
| Wells Fargo & Company/Mn | 0.00% | 10 | $79 | $18 | -$61 | -76.84% | |
| Osaic Holdings, Inc. | 0.00% | 8 | $63 | $15 | -$48 | -76.76% | |
| Larson Financial Group Llc | 0.00% | 5 | $39 | $9 | -$30 | -76.54% | |
| Whittier Trust Co Of Nevada Inc | 0.00% | 1 | $8 | $2 | -$6 | -77.13% |
Frequently asked questions about MCRB
Who are the largest institutional holders of MCRB?
The largest institutional holders of MCRB reported in the latest SEC Form 13F filings include Flagship Pioneering, Llc, Vanguard Capital Management Llc, Marshall Wace, Llp, Blackrock, Inc., and Geode Capital Management, Llc. InsiderSet ranks institutional holders by their latest reported MCRB position.
What is MCRB institutional ownership?
This page tracks MCRB positions reported by institutional investment managers through SEC Form 13F. SERES THERAPEUTICS INC (MCRB) institutional ownership on InsiderSet reflects disclosed 13F holdings among the managers we analyze, not every shareholder of the stock.
How many institutions own MCRB?
InsiderSet currently tracks 35 institutional managers reporting MCRB holdings in the latest available 13F data. This count reflects institutions included in the SEC Form 13F filings analyzed by InsiderSet and should not be interpreted as the total number of MCRB shareholders.
How much MCRB stock do institutions own?
Institutional investment managers disclosed approximately $17.35M in MCRB holdings for Q2 2026. This figure is reported 13F value as of the filing period, not necessarily today's market value.
When was MCRB institutional ownership last updated?
The latest MCRB institutional ownership data on InsiderSet is based on SEC Form 13F filings for the quarter ended June 30, 2026. Form 13F filings are generally reported after the quarter ends, so the holdings shown represent the latest publicly disclosed positions rather than real-time institutional holdings.
Are institutional MCRB holdings real-time?
No. Form 13F data is not real-time. It represents positions reported by institutional investment managers as of the end of the reporting quarter. An institution may have changed its MCRB position after the reporting date.
Are institutions buying or selling MCRB?
Institutional buying and selling can be analyzed by comparing MCRB positions across consecutive 13F reporting periods. InsiderSet's MCRB Ownership Changes page shows institutions that increased, reduced, initiated, or exited positions based on reported 13F holdings. View MCRB ownership changes.
How has MCRB institutional ownership changed over time?
InsiderSet tracks MCRB institutional holdings across multiple 13F reporting periods, allowing investors to compare institutional holder counts, reported value, and reported shares over time.