Biogen
BIIB
912 hedge funds and large institutions have $18.9B invested in Biogen in 2025 Q3 according to their latest regulatory filings, with 124 funds opening new positions, 325 increasing their positions, 270 reducing their positions, and 72 closing their positions.
81% more call options, than puts
Call options by funds: $573M | Put options by funds: $316M
72% more first-time investments, than exits
New positions opened: 124 | Existing positions closed: 72
48% more capital inflows, than outflows
Capital inflows: $1.69B | Capital outflows: $1.14B
20% more repeat investments, than reductions
Existing positions increased: 325 | Existing positions reduced: 270
5% more funds holding
Funds holding: 869 → 912 (+43)
2.67% more ownership
Funds ownership: 88.8% → 91.47% (+2.7%)
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 |
Norges Bank
Oslo,
Norway
|
+$71M |
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
912 of the 7,661 institutional investors tracked by Wall St. Rank reported a position in Biogen (BIIB) for Q3 2025, worth a combined $18.9B — up 15% from $16.3B a quarter earlier.
Buyers outnumbered sellers: 124 funds opened new BIIB positions and 72 closed out — a net gain of 52 holders — while 325 added to existing stakes and 270 trimmed.
The largest buyer was BlackRock, adding an estimated $163M. The largest seller was D.E. Shaw & Co, cutting an estimated $120M.
- 912 institutional investors held Biogen (BIIB) as of Q3 2025, up from 869 in Q2 2025.
- Funds reported $18.9B of Biogen stock for Q3 2025, up 15% quarter-over-quarter.
- 124 funds opened new Biogen positions in Q3 2025 and 72 closed out, a net change of +52 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.