Biogen
BIIB
908 hedge funds and large institutions have $18.5B invested in Biogen in 2025 Q3 according to their latest regulatory filings, with 124 funds opening new positions, 323 increasing their positions, 269 reducing their positions, and 73 closing their positions.
81% more call options, than puts
Call options by funds: $573M | Put options by funds: $316M
70% more first-time investments, than exits
New positions opened: 124 | Existing positions closed: 73
20% more repeat investments, than reductions
Existing positions increased: 323 | Existing positions reduced: 269
13% more capital invested
Capital invested by funds: $16.3B → $18.5B (+$2.13B)
5% more funds holding
Funds holding: 866 → 908 (+42)
0.77% more ownership
Funds ownership: 88.8% → 89.57% (+0.77%)
40% less funds holding in top 10
Funds holding in top 10: 5 → 3 (-2)
Top Buyers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
BlackRock
New York
|
+$163M |
| 2 |
Marshall Wace
London,
United Kingdom
|
+$97.6M |
| 3 |
Barclays
London,
United Kingdom
|
+$75.9M |
| 4 |
Pictet Asset Management
Carouge,
Switzerland
|
+$73.2M |
| 5 |
Caisse de Depot et Placement du Quebec (CDPQ)
Montreal,
Quebec, Canada
|
+$67.5M |
Top Sellers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
D.E. Shaw & Co
New York
|
-$120M |
| 2 |
Primecap Management
Pasadena,
California
|
-$115M |
| 3 |
Qube Research & Technologies (QRT)
London,
United Kingdom
|
-$84M |
| 4 |
Wellington Management Group
Boston,
Massachusetts
|
-$74.6M |
| 5 |
Two Sigma Advisers
New York
|
-$59.7M |
BIIB Hedge Fund Activity: Q3 2025 in Review
908 of the 7,639 institutional investors tracked by Wall St. Rank reported a position in Biogen (BIIB) for Q3 2025, worth a combined $18.5B — up 13% from $16.3B a quarter earlier.
Buyers outnumbered sellers: 124 funds opened new BIIB positions and 73 closed out — a net gain of 51 holders — while 323 added to existing stakes and 269 trimmed.
The largest buyer was BlackRock, adding an estimated $163M. The largest seller was D.E. Shaw & Co, cutting an estimated $120M.
- 908 institutional investors held Biogen (BIIB) as of Q3 2025, up from 866 in Q2 2025.
- Funds reported $18.5B of Biogen stock for Q3 2025, up 13% quarter-over-quarter.
- 124 funds opened new Biogen positions in Q3 2025 and 73 closed out, a net change of +51 holders.
- The largest Biogen buyer in Q3 2025 was BlackRock, an estimated $163M added.
- The largest Biogen seller in Q3 2025 was D.E. Shaw & Co, an estimated $120M sold.
Based on aggregated 13F filings for Q3 2025.