Biogen Inc.
Biogen Inc. (BIIB) Stock Ownership
Institutional vs insider vs public ownership from 13F and float data — top holders, activity, and insider trades below.
SEC 13F · FMP · BIIB · as of Sep 30, 2025
Ownership Breakdown
962
Institutional Holders
▲ 47 vs Q2
$18.47B
Total Inst. Value
▲ $2.11B vs Q2
147.64M
Shares Outstanding
freeFloat 99.12%
131.31M
13F Shares Held
▲ 1.08M vs Q2
Institutional ownership = 13F shares ÷ total outstanding. Insider % = 100 − free float. Public % = free float − institution %. Data: FMP /symbol-positions-summary + /shares-float + SEC EDGAR.
Top Institutional Holders
BIIB largest shareholders · institutional ownership
Q3 2025 · SEC 13F
Showing top 10 holders
| Holder | Shares | % Owned | Weight | Value | Reported | Change |
|---|---|---|---|---|---|---|
VANGUARD GROUP INC biological products, (no diagnostic substances) | 17.29M | 11.85% | 11.85% | $2.42T | Nov 7, 2025 | ▼ 1.4K |
PRIMECAP MANAGEMENT CO/CA/ biological products, (no diagnostic substances) | 14.95M | 10.25% | 10.25% | $2.09T | Nov 12, 2025 | ▼ 847.4K |
BLACKROCK, INC. biological products, (no diagnostic substances) | 14.76M | 10.12% | 10.12% | $2.07T | Nov 12, 2025 | ▲ 1.21M |
STATE STREET CORP biological products, (no diagnostic substances) | 7.32M | 5.02% | 5.02% | $1.03T | Nov 14, 2025 | ▼ 149.1K |
WELLINGTON MANAGEMENT GROUP LLP biological products, (no diagnostic substances) | 4.25M | 2.91% | 2.91% | $594.85B | Nov 14, 2025 | ▼ 551.9K |
GEODE CAPITAL MANAGEMENT, LLC biological products, (no diagnostic substances) | 4.07M | 2.79% | 2.79% | $567.74B | Nov 12, 2025 | ▲ 150.6K |
POINT72 ASSET MANAGEMENT, L.P. biological products, (no diagnostic substances) | 3.87M | 2.65% | 2.65% | $542.52B | Nov 14, 2025 | ▲ 41.2K |
INVESCO LTD. biological products, (no diagnostic substances) | 2.42M | 1.66% | 1.66% | $338.73B | Nov 13, 2025 | ▲ 98.0K |
MORGAN STANLEY biological products, (no diagnostic substances) | 2.25M | 1.54% | 1.54% | $315.40B | May 27, 2026 | ▲ 295.3K |
AQR CAPITAL MANAGEMENT LLC biological products, (no diagnostic substances) | 1.78M | 1.22% | 1.22% | $248.81B | Nov 14, 2025 | ▲ 418.8K |
Data from SEC Form 13F filings. Ownership bar normalised to largest holder. Change flags: isNew / isSoldOut / changeInSharesNumber (FMP extract-analytics/holder).
Institutional Activity
Q3 2025 vs prior quarter
Q3 2025
33
Increased
+8.62M shares0
New Positions
first time holders16
Decreased
−3.97M shares0
Sold Out
fully exitedNet shares change (top 50)
+4.65M
+8.62M / −3.97M
Net new holders
+17
0 new / 0 exited
Based on top 50 institutional holders by position size. Fields: isNew, isSoldOut, changeInSharesNumber (FMP extract-analytics/holder, limit=50).
Insider Buying vs Selling
BIIB insider trading · insider activity
Source: SEC Form 4
Insiders have been net buyers of shares recently. Selling may be driven by pre-scheduled Rule 10b5-1 plans rather than negative sentiment.
1
Buy transactions
2
Sell transactions
0.50
Buy/Sell ratio
$0M
Total disposed
Recent Insider Transactions
Showing 10 most recent · Common Stock only
| Name · Role | Date | Type | Shares | Price | Value | After Trans. | Filing |
|---|---|---|---|---|---|---|---|
Keeney Adam Head of Corporate Development | May 1, 2026 | Tax Withhold | 455 | $187.06 | $85.1K | 6.4K | Form 4 ↗ |
Godbout Sean Chief Accounting Officer | Apr 1, 2026 | Tax Withhold | 54 | $183.78 | $9.9K | 1.3K | Form 4 ↗ |
Murphy Nicole Head of Pharm Ops and Tech | Feb 12, 2026 | Purchase | 3 | $195.03 | $585.105 | 19.6K | Form 4 ↗ |
Viehbacher Christopher President and CEO | Feb 6, 2026 | Tax Withhold | 6,624 | $201.18 | $1.33M | 29.9K | Form 4 ↗ |
Source: /insider-trading/search (FMP stable). Buy/Sell direction: acquisitionOrDisposition A=Buy, D=Sell. RSU vesting (M-Exempt) excluded from sentiment bar. All data from SEC EDGAR public filings.
About institutional & insider ownership
Biogen Inc. (BIIB) is primarily owned by institutional investors, who hold approximately 88.9% of total shares outstanding. Company insiders own approximately 0.88%, while retail and public investors account for the remaining 10.18%.
The largest institutional shareholder of Biogen Inc. is VANGUARD GROUP INC, holding approximately 17.29 million shares — equal to 11.85% of outstanding shares — as of September 30, 2025.
A total of 962 institutional investors currently hold BIIB stock, with a combined institutional value of approximately $18.47 billion as of the most recent 13F filing period.
Frequently asked questions
BIIB ownershipBiogen Inc. (BIIB) is primarily owned by institutional investors, who hold approximately 88.9% of shares. The largest shareholder is VANGUARD GROUP INC with a 11.85% stake. Company insiders hold 0.88%. Data sourced from SEC Form 13F as of September 30, 2025.