MCRBNasdaqPharmaceutical PreparationsFiscal year ends December 31
Seres Therapeutics, Inc.
Financials through Q2 FY2026, quarter ended Jun 30, 2026Last filing: 10-Q on Aug 5, 2026
$2.42−0.04 (-1.63%)
Close on Oct 19, 2026
- Market cap
- $23.59M
- P/E (TTM)
- –
- Dividend yield
- –
Ownership
Institutional holdings as of Jun 30, 2026, from 13F filings
Held by institutions
22.9%
2M of 10M shares
Institutional holders
36
8 new, 5 sold out
Net institutional buying
-0M
In Q2 2026
Insider trades, 12 months
0 buys · 16 sales
Net sold $54.88K
Shares held by institutions
Holders of more than 5%
Latest Schedule 13D (active) or 13G (passive) filed by each holder
| Holder | Shares | % of class | Filing | As of |
|---|---|---|---|---|
| FMR LLC | 21,811,697 | 12.80% | 13G (passive) amendment | Dec 31, 2024 |
| Nestlé S.A. | 21,781,753 | – | 13D (active) amendment | Sep 30, 2024 |
Top institutional holders
13F holdings as of Jun 30, 2026
| Holder | Shares | % of MCRB | Value | Change | % of portfolio |
|---|---|---|---|---|---|
| Flagship Pioneering Inc. | 1,155,850 | 11.63% | $9.12M | – | 0.59% |
| Vanguard Capital Management LLC | 287,776 | 2.89% | $2.27M | −6,367 | 0.00% |
| Marshall Wace, Llp | 172,245 | 1.73% | $1.36M | +32,706 | 0.00% |
| Vontobel Holding Ltd. | 122,975 | 1.24% | $970.27K | −15,493 | 0.00% |
| BlackRock, Inc. | 111,000 | 1.12% | $875.79K | +8,974 | 0.00% |
| Geode Capital Management, LLC | 79,974 | 0.80% | $631.30K | +5,139 | 0.00% |
| Susquehanna International Group, Llp | 58,328 | 0.59% | $460.21K | −47,011 | 0.00% |
| Vanguard Fiduciary Trust Co | 48,685 | 0.49% | $384.13K | +9,042 | 0.00% |
| State Street Corp | 33,901 | 0.34% | $267.48K | – | 0.00% |
| Lion Point Capital, LP | 31,570 | 0.32% | $249.09K | – | 1.19% |
| Charles Schwab Investment Management Inc | 31,049 | 0.31% | $244.98K | −581 | 0.00% |
| American Century Companies Inc | 28,313 | 0.28% | $223.39K | −34,003 | 0.00% |
| XTX Topco Ltd | 20,732 | 0.21% | $163.58K | New | 0.00% |
| Goldman Sachs Group Inc | 15,229 | 0.15% | $120.16K | New | 0.00% |
| Northern Trust Corp | 14,765 | 0.15% | $116.50K | – | 0.00% |
| Invesco Ltd. | 12,974 | 0.13% | $102.37K | −1,573 | 0.00% |
| Morgan Stanley | 12,138 | 0.12% | $95.77K | −9,562 | 0.00% |
| Citadel Advisors LLC | 10,504 | 0.11% | $82.88K | New | 0.00% |
| Simplex Trading, LLC | 4,598 | 0.05% | $36.28K | +1,528 | 0.00% |
| SBI Securities Co., Ltd. | 4,182 | 0.04% | $33.00K | +700 | 0.00% |
Institutional buying and selling by quarter
Positions opened, added to, reduced and closed by 13F filers
| Quarter | Holders | Shares held | % of shares | New / added | Reduced / closed | Shares bought | Shares sold |
|---|---|---|---|---|---|---|---|
| Q2 2026 | 36 | 2M | 22.9% | 8 / 7 | 12 / 5 | 0M | 0M |
| Q1 2026 | 33 | 2M | 23.2% | 5 / 10 | 8 / 7 | 0M | 0M |
| Q4 2025 | 36 | 2M | 24.6% | 9 / 14 | 7 / 5 | 0M | 0M |
| Q3 2025 | 32 | 2M | 21.4% | 9 / 11 | 7 / 10 | 0M | 0M |
| Q2 2025 | 33 | 2M | 23.1% | 32 / 0 | 1 / 3 | 2M | 0M |
| Q1 2025 | 4 | 0M | 0.1% | 4 / 0 | 0 / 0 | 0M | 0M |
| Q1 2021 | 0 | 0M | 0.0% | 0 / 0 | 0 / 1 | 0M | 0M |
| Q4 2020 | 1 | 0M | 0.0% | 1 / 0 | 0 / 0 | 0M | 0M |
Top mutual fund and ETF holders
Latest monthly portfolio reports (Form N-PORT)
| Fund | Shares | % of MCRB | Value | % of fund | As of |
|---|---|---|---|---|---|
| Vanguard Total Stock Market Index Fund | 206,170 | 2.07% | $1.63M | 0.00% | Jun 30, 2026 |
| Vanguard Extended Market Index Fund | 75,849 | 0.76% | $598.45K | 0.00% | Jun 30, 2026 |
| Avantis U.S. Small Cap Value ETF | 37,364 | 0.38% | $273.50K | 0.00% | May 31, 2026 |
| Schwab U.S. Small-Cap ETF | 31,077 | 0.31% | $227.48K | 0.00% | May 31, 2026 |
| Fidelity Extended Market Index Fund | 26,335 | 0.26% | $192.77K | 0.00% | May 31, 2026 |
| iShares Micro-Cap ETF | 25,389 | 0.26% | $200.32K | 0.01% | Jun 30, 2026 |
| Fidelity Total Market Index Fund | 13,870 | 0.14% | $101.53K | 0.00% | May 31, 2026 |
| Invesco RAFI US 1500 Small-Mid ETF | 12,914 | 0.13% | $62.37K | 0.00% | Jul 31, 2026 |
| Fidelity Series Total Market Index Fund | 10,143 | 0.10% | $74.25K | 0.00% | May 31, 2026 |
| Goldman Sachs Absolute Return Tracker Fund | 10,065 | 0.10% | $79.41K | 0.00% | Jun 30, 2026 |
| U.S. Micro Cap Portfolio | 7,662 | 0.08% | $37.01K | 0.00% | Jul 31, 2026 |
| Ultra-Small Company Market Fund | 7,500 | 0.08% | $59.18K | 0.04% | Jun 30, 2026 |
| WisdomTree U.S. SmallCap Fund | 7,058 | 0.07% | $55.69K | 0.01% | Jun 30, 2026 |
| Fidelity Nasdaq Composite Index Fund | 5,666 | 0.06% | $41.48K | 0.00% | May 31, 2026 |
| Avantis U.S. Small Cap Equity ETF | 5,277 | 0.05% | $38.63K | 0.00% | May 31, 2026 |
Officers, directors and major owners
People who filed Forms 3, 4 or 5 in the last two years
| Name | Role | Shares owned | % of shares | Latest filing |
|---|---|---|---|---|
| Richard N. Kender | See Remarks, Director | 63,492 | 0.64% | Jul 10, 2026 |
| Thomas DesRosier | See Remarks | 8,117 | 0.08% | Aug 18, 2026 |
| Kelly Brady | See Remarks | 8,679 | 0.09% | Aug 18, 2026 |
| Matthew R. Henn | See Remarks | 7,995 | 0.08% | Aug 18, 2026 |
| Marella Thorell | See Remarks | – | – | Jul 10, 2026 |
| Teresa L. Young | See Remarks | 8,557 | 0.09% | Feb 18, 2026 |
| Moltke Lisa von | See Remarks | 39,875 | 0.40% | Feb 19, 2025 |
| Eric D. Shaff | Director | 12,499 | 0.13% | Aug 18, 2026 |
| Stephen Berenson | Director | 3,589 | 0.04% | Jul 10, 2026 |
| Robert L. Rosiello | Director | – | – | Jul 10, 2026 |
| Dennis A. Ausiello | Director | – | – | Jul 10, 2026 |
| Willard H. Dere | Director | 31,746 | 0.32% | Jul 10, 2026 |
| Claire Fraser | Director | – | – | Jul 10, 2026 |
| Kurt Graves | Director | – | – | Jul 10, 2026 |
| Paul Biondi | Director | 47,619 | 0.48% | Apr 11, 2025 |
| Hans-Juergen Woerle | Director | – | – | Feb 6, 2025 |
Insider trades
Common stock transactions reported on Form 4, newest first
| Insider | Date | Transaction | Shares | Price | Value | Shares after |
|---|---|---|---|---|---|---|
| Kelly Brady See Remarks | Aug 17, 2026 | Sale(10b5-1 plan) | −64 | $4.55 | $291 | 8,679 |
| Thomas DesRosier See Remarks | Aug 17, 2026 | Sale(10b5-1 plan) | −82 | $4.55 | $373 | 8,117 |
| Eric D. Shaff Director | Aug 17, 2026 | Sale(10b5-1 plan) | −263 | $4.55 | $1.20K | 12,499 |
| Matthew R. Henn See Remarks | Aug 17, 2026 | Sale(10b5-1 plan) | −81 | $4.55 | $369 | 7,995 |
| Kelly Brady See Remarks | Aug 15, 2026 | Option exercise | +181 | – | – | 8,743 |
| Thomas DesRosier See Remarks | Aug 15, 2026 | Option exercise | +245 | – | – | 8,199 |
| Eric D. Shaff Director | Aug 15, 2026 | Option exercise | +722 | – | – | 12,762 |
| Matthew R. Henn See Remarks | Aug 15, 2026 | Option exercise | +238 | – | – | 8,076 |
| Thomas DesRosier See Remarks | May 18, 2026 | Sale(10b5-1 plan) | −79 | $7.53 | $595 | 7,954 |
| Kelly Brady See Remarks | May 18, 2026 | Sale | −59 | $7.53 | $444 | 8,562 |
| Eric D. Shaff Director | May 18, 2026 | Sale(10b5-1 plan) | −259 | $7.53 | $1.95K | 12,040 |
| Matthew R. Henn See Remarks | May 18, 2026 | Sale(10b5-1 plan) | −77 | $7.53 | $580 | 7,838 |
| Thomas DesRosier See Remarks | May 15, 2026 | Option exercise | +244 | – | – | 8,033 |
| Kelly Brady See Remarks | May 15, 2026 | Option exercise | +180 | – | – | 8,621 |
| Eric D. Shaff Director | May 15, 2026 | Option exercise | +722 | – | – | 12,299 |
| Matthew R. Henn See Remarks | May 15, 2026 | Option exercise | +238 | – | – | 7,915 |
| Teresa L. Young See Remarks | Feb 15, 2026 | Sale(10b5-1 plan) | −75 | $8.47 | $635 | 8,557 |
| Teresa L. Young See Remarks | Feb 15, 2026 | Option exercise | +231 | – | – | 8,632 |
| Thomas DesRosier See Remarks | Feb 15, 2026 | Option exercise | +244 | – | – | 7,867 |
| Thomas DesRosier See Remarks | Feb 15, 2026 | Sale(10b5-1 plan) | −78 | $8.47 | $661 | 7,789 |
| Eric D. Shaff Director | Feb 15, 2026 | Sale(10b5-1 plan) | −259 | $8.47 | $2.19K | 11,577 |
| Eric D. Shaff Director | Feb 15, 2026 | Option exercise | +723 | – | – | 11,836 |
| Matthew R. Henn See Remarks | Feb 15, 2026 | Sale(10b5-1 plan) | −89 | $8.47 | $754 | 7,677 |
| Matthew R. Henn See Remarks | Feb 15, 2026 | Option exercise | +239 | – | – | 7,766 |
| Thomas DesRosier See Remarks | Nov 15, 2025 | Sale(10b5-1 plan) | −76 | $17.30 | $1.31K | 7,623 |
| Thomas DesRosier See Remarks | Nov 15, 2025 | Option exercise | +112 | – | – | 7,699 |
| Thomas DesRosier See Remarks | Nov 15, 2025 | Option exercise | +132 | – | – | 7,587 |
| Teresa L. Young See Remarks | Nov 15, 2025 | Option exercise | +132 | – | – | 9,345 |
| Teresa L. Young See Remarks | Nov 15, 2025 | Option exercise | +98 | – | – | 9,443 |
| Teresa L. Young See Remarks | Nov 15, 2025 | Option exercise | +3,998 | – | – | 9,213 |
| Teresa L. Young See Remarks | Nov 15, 2025 | Sale(10b5-1 plan) | −1,042 | $17.30 | $18.03K | 8,401 |
| Matthew R. Henn See Remarks | Nov 15, 2025 | Option exercise | +140 | – | – | 8,686 |
| Matthew R. Henn See Remarks | Nov 15, 2025 | Option exercise | +3,998 | – | – | 8,546 |
| Matthew R. Henn See Remarks | Nov 15, 2025 | Option exercise | +98 | – | – | 8,784 |
| Matthew R. Henn See Remarks | Nov 15, 2025 | Sale(10b5-1 plan) | −1,257 | $17.30 | $21.75K | 7,527 |
| Eric D. Shaff Director | Nov 15, 2025 | Option exercise | +390 | – | – | 10,999 |
| Eric D. Shaff Director | Nov 15, 2025 | Option exercise | +331 | – | – | 11,330 |
| Eric D. Shaff Director | Nov 15, 2025 | Sale(10b5-1 plan) | −217 | $17.30 | $3.75K | 11,113 |
| Teresa L. Young See Remarks | Aug 18, 2025 | Sale(10b5-1 plan) | −59 | $16.65 | $982 | 5,215 |
| Thomas DesRosier See Remarks | Aug 18, 2025 | Sale(10b5-1 plan) | −76 | $16.65 | $1.27K | 7,455 |
| Eric D. Shaff Director | Aug 18, 2025 | Sale(10b5-1 plan) | −217 | $16.65 | $3.61K | 10,609 |
| Matthew R. Henn See Remarks | Aug 18, 2025 | Sale(10b5-1 plan) | −73 | $16.65 | $1.22K | 4,548 |
| Teresa L. Young See Remarks | Aug 15, 2025 | Option exercise | +97 | – | – | 5,274 |
| Teresa L. Young See Remarks | Aug 15, 2025 | Option exercise | +133 | – | – | 5,177 |
| Thomas DesRosier See Remarks | Aug 15, 2025 | Option exercise | +133 | – | – | 7,420 |
| Thomas DesRosier See Remarks | Aug 15, 2025 | Option exercise | +111 | – | – | 7,531 |
| Eric D. Shaff Director | Aug 15, 2025 | Option exercise | +391 | – | – | 10,493 |
| Eric D. Shaff Director | Aug 15, 2025 | Option exercise | +333 | – | – | 10,826 |
| Matthew R. Henn See Remarks | Aug 15, 2025 | Option exercise | +141 | – | – | 4,524 |
| Matthew R. Henn See Remarks | Aug 15, 2025 | Option exercise | +97 | – | – | 4,621 |
| Teresa L. Young See Remarks | May 16, 2025 | Sale(10b5-1 plan) | −63 | $7.28 | $459 | 5,044 |
| Matthew R. Henn See Remarks | May 16, 2025 | Sale(10b5-1 plan) | −77 | $7.28 | $561 | 4,383 |
| Eric D. Shaff CEO and President, Director | May 16, 2025 | Sale(10b5-1 plan) | −220 | $7.28 | $1.60K | 10,102 |
| Teresa L. Young See Remarks | May 15, 2025 | Option exercise | +98 | – | – | 5,107 |
| Teresa L. Young See Remarks | May 15, 2025 | Option exercise | +133 | – | – | 5,009 |
| Thomas DesRosier Chief Legal Officer and EVP | May 15, 2025 | Option exercise | +111 | – | – | 7,366 |
| Thomas DesRosier Chief Legal Officer and EVP | May 15, 2025 | Option exercise | +133 | – | – | 7,255 |
| Thomas DesRosier Chief Legal Officer and EVP | May 15, 2025 | Sale(10b5-1 plan) | −79 | $7.28 | $575 | 7,287 |
| Matthew R. Henn See Remarks | May 15, 2025 | Option exercise | +98 | – | – | 4,460 |
| Matthew R. Henn See Remarks | May 15, 2025 | Option exercise | +140 | – | – | 4,362 |
Awards, option exercises, tax withholding and gifts are shown alongside open-market buys and sales. Each name links to the filing on SEC EDGAR.
Planned insider sales
Notices of proposed sale filed on Form 144 before shares are sold
| Seller | Filed | Shares | Market value | Planned sale | Acquired through |
|---|---|---|---|---|---|
| L. Young Teresa Officer | May 19, 2026 | 167 | $1.28K | May 19, 2026 | Restricted Stock |
| L. Young Teresa Officer | Mar 17, 2026 | 8,553 | $77.97K | Mar 17, 2026 | Restricted and Performance Shares |