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Smart Money Score
Composite context from Form 4, 13F and congressional disclosures; not a forecast.
Of the 14 tracked institutions holding BIIB, 7 have a 3-year clone track record — 7 of them beat the S&P. Average holder's clone alpha: +5.7pt. It's a gauge of who owns the name, not just how many.
Among the 14 tracked institutional investors we monitor, BIIB (BIOGEN INC) is held with a combined value of $13.59B across 66,163,571 shares. The largest holder is FMR LLC with a position worth $3.94B (0.17% of their portfolio). 9 funds increased their holdings. 5 funds reduced their position.
Total Institutional Value
$13.59B
Total Shares Held
66,163,571
Institutional Holders
14
% of Shares Outstanding
45.1%
of 146.80M shares · SEC 2025-12-31
Days to Cover
6.1-4.8%
5.19M shares short · FINRA 2026-08-14
Tracked 13F institutions hold 45.1% of BIIB's shares outstanding. This is a floor: 13F filings arrive on a ~45-day lag and we track only a subset of institutional filers, so true institutional ownership is higher. Shares-outstanding is the latest SEC cover-page figure (as of 2025-12-31), not a live float.
Ranked by estimated dollars moved (share change × implied price). 13F data lags up to 45 days.
0
$0
2
$239.75K
Total Transactions
2
Last 12 months
| Date | Insider | Code | Type | Shares | Value |
|---|---|---|---|---|---|
| Aug 4, 2026 | Lloyd Minor | S | Sale | 593 | $119.17K |
| Aug 3, 2026 | Lloyd Minor | S | Sale | 593 | $120.58K |
| # | Fund | Value↓ | Portfolio % | Change |
|---|---|---|---|---|
| 1 | FMR LLC | $3.94B | 0.17% | +42.2% |
| 2 | BlackRock, Inc. | $3.45B | 0.05% | +0.1% |
| 3 | VANGUARD GROUP INC | $3.07B | 0.04% | +0.9% |
| 4 | STATE STREET CORP | $1.59B | 0.05% | +2.5% |
| 5 | WELLINGTON MANAGEMENT GROUP LLP | $673.56M | 0.12% | +5.3% |
| 6 | AQR CAPITAL MANAGEMENT LLC | $416.93M | 0.15% | +0.7% |
| 7 | PRICE T ROWE ASSOCIATES INC /MD/ | $167.29M | 0.02% | +15.1% |
| 8 | CITADEL ADVISORS LLC | $90.39M | 0.05% | +203.0% |
| 9 | Fisher Asset Management, LLC | $73.03M | 0.02% | +8.1% |
| 10 | Gotham Asset Management, LLC | $60.48M | 0.14% | -6.2% |
SEC Schedule 13D (activist) and 13G (passive) filings for BIIB. Filed when an investor acquires 5%+ ownership.
| Member | Type | Date |
|---|---|---|
| Kevin Hern | Sell | Aug 18, 2026 |
| Gilbert Cisneros | Buy | Jun 5, 2026 |
| Maria Elvira Salazar | Sell | Jun 2, 2026 |
| Maria Elvira Salazar | Buy |
As of the latest SEC 13F filings, FMR LLC is the largest institutional holder of BIIB with a position worth $3.94B, representing 0.17% of their portfolio. In total, 14 institutional investors hold BIIB with a combined value of $13.59B.
Institutional investors hold $13.59B worth of BIIB stock across 14 positions. The largest institutional holder is FMR LLC with $3.94B in holdings.
A 13F filing is a quarterly report required by the SEC from institutional investment managers with over $100 million in assets. It discloses their holdings in U.S. equities. For BIIB, these filings reveal which major funds are accumulating or reducing positions, providing insights into institutional sentiment.
Get notified when hedge funds change their BIIB positions.
Alpha = the manager's 3-year clone return minus the S&P 500. A skilled roster is a stronger tell than a crowded one — though even skilled managers' edge doesn't reliably survive the 13F disclosure lag. Why →
| May 12, 2026 |
| Maria Elvira Salazar | Buy | May 11, 2026 |
| Maria Elvira Salazar | Buy | May 11, 2026 |
| Alan Armstrong | Buy | Mar 27, 2026 |
| Gilbert Cisneros | Buy | Jan 30, 2026 |
Showing 8 of 25. STOCK Act disclosures lag up to 45 days.
Last Close
$210.73
2026-09-09
YTD
+18.5%
84% of 52-week range
