Biogen
BIIB
1,003 hedge funds and large institutions have $24.7B invested in Biogen in 2026 Q1 according to their latest regulatory filings, with 134 funds opening new positions, 398 increasing their positions, 290 reducing their positions, and 106 closing their positions.
37% more repeat investments, than reductions
Existing positions increased: 398 | Existing positions reduced: 290
26% more first-time investments, than exits
New positions opened: 134 | Existing positions closed: 106
1% more funds holding
Funds holding: 997 → 1,003 (+6)
1% more capital invested
Capital invested by funds: $24.6B → $24.7B (+$135M)
10% less call options, than puts
Call options by funds: $324M | Put options by funds: $360M
3.33% less ownership
Funds ownership: 95.27% → 91.94% (-3.3%)
13% less funds holding in top 10
Funds holding in top 10: 8 → 7 (-1)
Top Buyers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
Fidelity Investments
Boston,
Massachusetts
|
+$623M |
| 2 |
BlackRock
New York
|
+$214M |
| 3 |
AQR Capital Management
Greenwich,
Connecticut
|
+$72.8M |
| 4 |
AIM
Artemis Investment Management
Edinburgh,
United Kingdom
|
+$63.5M |
| 5 |
SI
Sofinnova Investments
Menlo Park,
California
|
+$42.3M |
Top Sellers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
Point72 Asset Management
Stamford,
Connecticut
|
-$369M |
| 2 |
Millennium Management
New York
|
-$190M |
| 3 |
Barclays
London,
United Kingdom
|
-$139M |
| 4 |
Wellington Management Group
Boston,
Massachusetts
|
-$109M |
| 5 |
Susquehanna International Group
Bala Cynwyd,
Pennsylvania
|
-$96.1M |
BIIB Hedge Fund Activity: Q1 2026 in Review
1,003 of the 8,130 institutional investors tracked by Wall St. Rank reported a position in Biogen (BIIB) for Q1 2026, worth a combined $24.7B — up 0.55% from $24.6B a quarter earlier.
Buyers outnumbered sellers: 134 funds opened new BIIB positions and 106 closed out — a net gain of 28 holders — while 398 added to existing stakes and 290 trimmed.
The largest buyer was Fidelity Investments, adding an estimated $623M. The largest seller was Point72 Asset Management, cutting an estimated $369M.
- 1,003 institutional investors held Biogen (BIIB) as of Q1 2026, up from 997 in Q4 2025.
- Funds reported $24.7B of Biogen stock for Q1 2026, up 0.55% quarter-over-quarter.
- 134 funds opened new Biogen positions in Q1 2026 and 106 closed out, a net change of +28 holders.
- The largest Biogen buyer in Q1 2026 was Fidelity Investments, an estimated $623M added.
- The largest Biogen seller in Q1 2026 was Point72 Asset Management, an estimated $369M sold.
Based on aggregated 13F filings for Q1 2026.