Biogen
BIIB · NASDAQ
Who owns BIIB
Largest institutional holders, from their latest 13F filings
The 10 largest institutions hold 51.4% of BIIB’s shares.
- Fidelity Management & Research Company LLC10.3%
- PRIMECAP Management Company10.3%
- Vanguard Capital Management, LLC6.5%
- BlackRock Institutional Trust Company, N.A.6.2%
- Next 6 largest institutions18.1%
- All other shareholders48.6%
| Holder | Shares | % of shares |
|---|---|---|
| Fidelity Management & Research Company LLC | 15.27M | 10.34% |
| PRIMECAP Management Company | 15.15M | 10.26% |
| Vanguard Capital Management, LLC | 9.65M | 6.53% |
| BlackRock Institutional Trust Company, N.A. | 9.22M | 6.24% |
| State Street Investment Management (US) | 7.34M | 4.97% |
| Vanguard Portfolio Management, LLC | 6.60M | 4.47% |
| Geode Capital Management, L.L.C. | 4.45M | 3.01% |
| Wellington Management Company, LLP | 3.12M | 2.11% |
| Fidelity Institutional Asset Management | 2.61M | 1.77% |
| Norges Bank Investment Management (NBIM) | 2.58M | 1.75% |
Largest mutual fund holders
| Holder | Shares | % of shares |
|---|---|---|
| Vanguard PRIMECAP Fund | 8.36M | 5.66% |
| Fidelity Contrafund | 4.98M | 3.37% |
| Vanguard Total Stock Market Index Fund | 4.70M | 3.18% |
| Vanguard 500 Index Fund | 3.88M | 2.62% |
| Vanguard Mid-Cap Index Fund | 3.20M | 2.16% |
Insider trades
Form 4 filings by officers, directors and large holders
Over the last 6 months, insiders sold $239.75K (2 trades) of BIIB on the open market, with no buys.
| Insider | Type | Shares | Value |
|---|---|---|---|
| Godbout Sean | Option exercise | 27 | — |
| Godbout Sean | Tax withholding | 8 | $1.76K |
| Godbout Sean | Option exercise | 27 | — |
| Godbout Sean | Award | 985 | — |
| Parini Michael | Award | 7.41K | — |
| Minor Lloyd | Sale | 593 | $119.17K |
| Minor Lloyd | Sale | 593 | $120.58K |
| Minor Lloyd | Award | 1.50K | — |
| Pangalos Menelas N | Option exercise | 2.37K | — |
| Pangalos Menelas N | Award | 1.50K | — |
Congressional trades
Disclosed by members of Congress over the last 12 months
| Member | Type | Amount | Traded |
|---|---|---|---|
| Maria ElviraHouse | Sale | $1K–$15K | Sep 24, 2026 |
| Kevin HernHouse | Sale | $1K–$15K | Aug 18, 2026 |
| Maria ElviraHouse | Sale | $15K–$50K | Jun 2, 2026 |
| Alan ArmstrongSenator | Purchase | $1K–$15K | Mar 27, 2026 |
| Gil CisnerosHouse | Purchase | $1K–$15K | Jan 30, 2026 |
Short interest
Settled Sep 30, 2026
- Shares short
- 5.97M
- Days to cover
- 4.87
- % of shares outstanding
- 4.04%
- Average daily volume
- 1.23M
- Change since last report
- +2.5%
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