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Who owns Biogen (BIIB) stock

998 funds reported Biogen (BIIB) shares in their latest 13F filings, worth $32.5B in all. The largest holder is FMR LLC ($3.9B). Last quarter 482 funds added to their stakes and 353 cut them. Members of Congress and other officials disclosed 9 trades (6 buys, 3 sales).

Largest holders of BIIB (13F)Largest holders of BIIB (13F)FMR LLC$3.9BBlackRock$3.5BPrimecap Management$3.3BVanguard Group$3.1BVanguard Capital Management LLC$2.1BState Street$1.6BVanguard Portfolio Management LLC$1.4BGeode Capital Management, LLC$958MWellington Management Group LLP$674MMorgan Stanley$521M

Largest holders (13F)

FundSharesValueChangeQuarter
FMR LLC18,217,239$3.9Bincrease2026-06-30
BlackRock15,985,736$3.5Bincrease2026-06-30
Primecap Management15,154,606$3.3Bincrease2026-06-30
Vanguard Group17,447,092$3.1Bincrease2025-12-31
Vanguard Capital Management LLC9,651,117$2.1Bincrease2026-06-30
State Street7,344,327$1.6Bincrease2026-06-30
Vanguard Portfolio Management LLC6,604,936$1.4Bincrease2026-06-30
Geode Capital Management, LLC4,449,295$958Mincrease2026-06-30
Wellington Management Group LLP3,117,469$674Mincrease2026-06-30
Morgan Stanley2,411,271$521Mincrease2026-06-30
AQR Capital Management LLC1,936,859$417Mincrease2026-06-30
Invesco1,803,944$390Mincrease2026-06-30
Legal & General Group1,493,289$323Mincrease2026-06-30
Northern Trust1,429,490$309Mdecrease2026-06-30
Amundi1,316,534$297Mdecrease2026-09-30

Trades by Congress and other officials

DateWhoTradeAmount
2026-09-24Maria Elvira Salazarpartial sale$1K–$15K
2026-08-18Kevin Hernsale$1K–$15K
2026-06-05Gilbert Cisnerospurchase$1K–$15K
2026-06-02Maria Elvira Salazarsale$15K–$50K
2026-05-12Maria Elvira Salazarpurchase$1K–$15K
2026-05-11Maria Elvira Salazarpurchase$1K–$15K
2026-05-11Maria Elvira Salazarpurchase$50K–$100K
2026-03-27Alan Armstrongpurchase$1K–$15K
2026-01-30Gilbert Cisnerospurchase$1K–$15K

Biogen's latest quarter

Biogen, Q3 2026: revenue $2.8B (+11% year over year), operating margin -0.3%, net loss $20.6M, operating cash flow $641M. The chart follows the revenue to costs, profit and cash.

Questions

Who owns the most BIIB stock?

By the latest 13F filings: FMR LLC ($3.9B); BlackRock ($3.5B); Primecap Management ($3.3B); Vanguard Group ($3.1B); Vanguard Capital Management LLC ($2.1B).

Has Congress traded BIIB stock?

Officials disclosed 9 trades on file: 6 buys and 3 sales. The latest: Maria Elvira Salazar, partial sale on 2026-09-24.

What is the short interest in BIIB?

5,500,386 shares were sold short at the 2026-10-15 settlement, -7.8% of the float.

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Updated Nov 8, 2026. Read automatically from SEC filings and public data; errors are possible. Not investment advice.