BIIB Institutional Ownership
Who owns Biogen Inc. and what the big funds did with it last quarter, from every SEC 13F filing. 1,043 funds reported holding BIIB at Jun 30, 2026, together owning 96.3% of the company.
- ▲535 buying vs 373 selling
- ▲Held by funds +4.9 pts
- ▲Funds holding +28
- ▼Superinvestors: 1 added, 3 cut
- ▲Put/call 1.05 to 0.48
What the filings show, not a forecast. Positions can be up to 45 days old and leave out short sales.
Funds holding and ownership
8 quartersQuarter over quarter
all 13F filers| Q2 2026 | This quarter | Q1 2026 | Change |
|---|---|---|---|
| Funds holding | 1,043 | 1,015 | +2.8% |
| In funds' top 10 | 9 | 8 | +12.5% |
| 13F shares | 142M | 135M | +5.4% |
| Held by funds | 96.3% | 91.4% | +4.9 pts |
| New positions | 111 | 114 | −2.6% |
| Increased | 424 | 394 | +7.6% |
| Reduced | 290 | 291 | −0.3% |
| Sold out | 83 | 107 | −22.4% |
| Calls (shares) | 1M | 187K | +442.2% |
| Puts (shares) | 484K | 395K | +22.5% |
| Put/call ratio | 0.48 | 1.05 | −54.7% |
Buyers vs sellers
adding or new vs cutting or sold outSuperinvestors in BIIB
All superinvestors →
Who owns BIIB
share of fund held shares- Index and passive funds37.5%
- Active managers and hedge funds46.3%
- Banks and brokers12.1%
- Pensions, insurers and other4.0%
The top 10 holders own 60.1% of all BIIB shares that funds reported. Groups are our own grouping of filers by name.
Put/call ratio
funds' options, market makers left outAbove 1 means funds hold more puts than calls, a sign of hedging or bets on a fall. Options are valued at the underlying shares.
Filed so far for Q3 2026
310 funds changed their position- B. Metzler seel. Sohn & Co. AGAdded+391K sh
- Robeco Institutional Asset Management B.V.Trimmed−135K sh
- DekaBank Deutsche GirozentraleAdded+45K sh
- Fideuram - Intesa Sanpaolo Private Banking S.p.a.Added+34K sh
- Mackenzie Financial CorpTrimmed−25K sh
🔒 Free account: see all 20.
Top holders
Q2 2026| # | Fund | Of company | Shares | Value | Change |
|---|---|---|---|---|---|
| 1 | Fmr LLC | 12.32% | 18.2M | $3.9B | +5.4M |
| 2 | BlackRock, Inc. | 10.81% | 16M | $3.5B | +11K |
| 3 | Primecap Management Co/ca/ | 10.25% | 15.2M | $3.3B | +397K |
| 4 | Vanguard Capital Management LLC | 6.53% | 9.7M | $2.1B | +114K |
| 5 | State Street Corp | 4.97% | 7.3M | $1.6B | +176K |
| 6 | Vanguard Portfolio Management LLC | 4.47% | 6.6M | $1.4B | +73K |
| 7 | Geode Capital Management, LLC | 3.01% | 4.4M | $958M | +107K |
| 8 | Wellington Management Group LLP | 2.11% | 3.1M | $674M | +156K |
| 9 | Norges Bank | 1.75% | 2.6M | $557M | +2.6M |
| 10 | Morgan Stanley | 1.63% | 2.4M | $521M | +240K |
- Fmr LLC+5.4M sh+$1.2B
- Norges Bank+2.6M sh+$557M
- Amundi+726K sh+$157M
- UBS Group AG+507K sh+$109M
- Pacer Advisors, Inc.+463K sh+$99.9M
- Primecap Management Co/ca/+397K sh+$85.8M
- Citadel Advisors LLC+280K sh+$60.6M
- Perceptive Advisors LLC+276K sh+$59.7M
- T. Rowe Price Investment Management, Inc.−1M sh−$226M
- Van Eck Associates Corp−982K sh−$212M
- Point72 Asset Management, L.P.−721K sh−$156M
- Boston Partners−437K sh−$94.3M
- Balyasny Asset Management L.P.−385K sh−$83.2M
- Barclays PLC−304K sh−$65.8M
- Marshall Wace, LLP−217K sh−$46.9M
- Adage Capital Partners Gp, L.l.c.−204K sh−$44M
BIIB institutional ownership FAQ
Who owns the most BIIB stock?
In Q2 2026 13F filings the largest holder of BIIB was Fmr LLC, followed by BlackRock, Inc. and Primecap Management Co/ca/. Index fund managers are usually the biggest holders of large companies.
What percentage of BIIB is owned by institutions?
Funds that file 13F reports held 96.3% of BIIB's shares at Jun 30, 2026, compared with 91.4% a quarter earlier. That counts every manager with more than $100 million in US stocks.
Are hedge funds buying BIIB?
In Q2 2026, 535 funds bought BIIB (111 of them new positions) and 373 sold (83 sold out completely). Among well known investors, 1 added and 3 cut. Our fund sentiment for BIIB is bullish.
What is BIIB's institutional put/call ratio?
Funds reported $105M of BIIB puts against $219M of calls, a put/call ratio of 0.48 (1.05 the quarter before). Market makers and bank trading desks are left out, since their options are mostly hedges.
How current is this BIIB ownership data?
13F filings show holdings at the end of each quarter and are due within 45 days, so positions can be up to six weeks old when they appear. We add each new filing within minutes, and the "filed so far" list shows funds that have already reported the next quarter.
For informational and educational purposes only. Not investment advice, and not a recommendation to buy or sell any security. Fund sentiment summarises what 13F filings show and is not a forecast. Holdings come from SEC Form 13F filings as reported and show positions at the end of the quarter, up to 45 days before the filing. A 13F leaves out short positions, cash, bonds and most foreign holdings. See all hedge fund holdings.