Biogen BIIB Institutional Ownership

Updated Oct 21, 2026

Biogen Inc. (NASDAQ:BIIB) counted 1,036 institutional investors among its 13F-reported shareholders for the quarter ended June 30, 2026.

• These investors held 96.38% of Biogen's outstanding shares at the end of Q2 2026, up from 91.03% in Q1 2026.
• Total holdings of BIIB shares rose 5.97% from Q1 2026, and the holder count rose 20.47% from Q2 2025.
• Looking at the 1,036 holders of BIIB individually, 548 added to their positions, 294 reduced their stakes and 194 left their positions unchanged.
• Altogether, institutional holders owned 142.41Mn BIIB shares at the end of Q2 2026, up 8.02Mn from the prior quarter and up 14.95Mn from a year earlier.
• As of June 30, 2026, the biggest holder of Biogen was FMR LLC with 18.22Mn shares, or 12.33% of shares outstanding.
• Among holders that already owned Biogen, the biggest buyers in Q2 2026 were FMR LLC (+5.41Mn shares), Amundi (+726K shares), UBS Group AG (+506.7K shares), Primecap Management Co (+397K shares) and Citadel Advisors LLC (+280.26K shares).
• The biggest cuts to BIIB positions during Q2 2026 came from T. Rowe Price Investment Management, Inc. (-1.05Mn shares), Van Eck Associates Corp (-981.75K shares), Point72 Asset Management, L.P. (-721.47K shares), Boston Partners (-436.65K shares) and Balyasny Asset Management L.P. (-384.96K shares).
• According to Business Quant data, the leading holders of BIIB for Q2 2026 were FMR LLC (18.22Mn shares), BlackRock, Inc. (15.99Mn shares), Primecap Management Co (15.15Mn shares), Vanguard Capital Management LLC (9.65Mn shares), State Street Corp (7.34Mn shares), Vanguard Portfolio Management LLC (6.6Mn shares), Geode Capital Management, LLC (4.45Mn shares), Wellington Management Group LLP (3.12Mn shares), Norges Bank (2.58Mn shares) and Morgan Stanley (2.41Mn shares).