Biogen Inc. (BIIB) ownership: Top institutional holder: VANGUARD GROUP INC ($3.07B). Insider activity: Net Seller (0 buys, 20 sells). 10 recent congressional STOCK Act disclosures. SEC EDGAR first-party data.
| Holder | Shares | Market Value | Reported |
|---|---|---|---|
| VANGUARD GROUP INC | 17447092.00 | $3.07B | 2025-12-31 |
| BlackRock, Inc. | 15974601.00 | $2.93B | 2026-03-31 |
| PRIMECAP MANAGEMENT CO/CA/ | 14757607.00 | $2.71B | 2026-03-31 |
| FMR LLC | 12807541.00 | $2.35B | 2026-03-31 |
| VANGUARD CAPITAL MANAGEMENT LLC | 9537417.00 | $1.75B | 2026-03-31 |
| BlackRock Fund Advisors | 5298451.00 | $1.50B | 2016-12-31 |
| STATE STREET CORP | 7167922.00 | $1.31B | 2026-03-31 |
| VANGUARD PORTFOLIO MANAGEMENT LLC | 6531727.00 | $1.20B | 2026-03-31 |
| Insider | Transaction | Value | Date |
|---|---|---|---|
| Sell | null | 2026-06-09 | |
| Sell | null | 2026-06-09 | |
| Sell | null | 2026-06-09 | |
| Sell | null | 2026-06-09 | |
| Sell | null | 2026-06-09 | |
| Sell | null | 2026-06-09 | |
| Sell | null | 2026-06-09 | |
| Sell | null | 2026-06-09 |
Back to BIIB overview · BIIB earnings · All congressional trades
Institutional data from SEC Form 13F. Insider data from SEC Form 4. Congressional data from STOCK Act disclosures. Not personalized investment advice.