Seres Therapeutics, Inc. (MCRB) ownership: Top institutional holder: BlackRock Fund Advisors ($10.92M). Insider activity: Net Seller (0 buys, 20 sells). SEC EDGAR first-party data.
| Holder | Shares | Market Value | Reported |
|---|---|---|---|
| BlackRock Fund Advisors | 1103382.00 | $10.92M | 2016-12-31 |
| Flagship Pioneering, LLC | 1155850.00 | $10.25M | 2026-03-31 |
| VANGUARD GROUP INC | 324214.00 | $4.82M | 2025-12-31 |
| VANGUARD CAPITAL MANAGEMENT LLC | 294143.00 | $2.61M | 2026-03-31 |
| MARSHALL WACE, LLP | 139539.00 | $1.24M | 2026-03-31 |
| Vontobel Holding Ltd. | 138468.00 | $1.23M | 2026-03-31 |
| Caption Management, LLC | 75000.00 | $1.12M | 2025-12-31 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | 105339.00 | $934357.00 | 2026-03-31 |
| Insider | Transaction | Value | Date |
|---|---|---|---|
| Sell | null | 2026-05-18 | |
| Sell | null | 2026-05-18 | |
| Sell | null | 2026-05-18 | |
| Sell | null | 2026-05-18 | |
| Sell | null | 2026-05-15 | |
| Sell | null | 2026-05-15 | |
| Sell | null | 2026-05-15 | |
| Sell | null | 2026-05-15 |
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Institutional data from SEC Form 13F. Insider data from SEC Form 4. Congressional data from STOCK Act disclosures. Not personalized investment advice.