Biogen Inc. (BIIB) Institutional Ownership

Ownership Summary

Biogen Inc. (NASDAQ:BIIB) has 967 institutional investors that have filed 13F reports for the period ending December 2025.

• Their combined ownership stood at 95.1% of outstanding shares in December 2025, up from 91.3% in September 2025.
• They increased total shares held in BIIB by 6.46% quarter over quarter, and investors in Biogen increased 12.7% from a year ago.
• Of these 967 holders, 492 added to their stakes in Biogen, 294 trimmed positions, and 181 made no changes.
• Institutional investors collectively held 139.93Mn shares in Biogen as of December 2025, up by 8.49Mn shares quarter on quarter, and up 3.87Mn shares year over year.
• As of December 31, 2025, BlackRock, Inc. held the largest stake in Biogen with 15.97Mn shares, accounting for 10.86% of total shares outstanding.
• Top purchasers of BIIB stock for the quarter ending December 2025 included VANGUARD CAPITAL MANAGEMENT LLC (9.54Mn), VANGUARD PORTFOLIO MANAGEMENT LLC (6.53Mn), FMR LLC (3.38Mn), BlackRock, Inc. (1.16Mn), VANGUARD FIDUCIARY TRUST CO (825.53K).
• The biggest sellers of Biogen for the quarter ending December 2025 included Point72 Asset Management, L.P. (2.0Mn), Goldman Sachs Group Inc (1.15Mn), MILLENNIUM MANAGEMENT LLC (1.03Mn), T. Rowe Price Investment Management, Inc. (788.38K), Barclays Plc (753.53K).
• Biogen's 10 largest shareholders as of December 2025 include BlackRock, Inc. (15.97Mn), PRIMECAP MANAGEMENT CO/CA/ (14.76Mn), FMR LLC (12.81Mn), VANGUARD CAPITAL MANAGEMENT LLC (9.54Mn), State Street Corp (7.17Mn), VANGUARD PORTFOLIO MANAGEMENT LLC (6.53Mn), GEODE CAPITAL MANAGEMENT, LLC (4.34Mn), WELLINGTON MANAGEMENT GROUP LLP (2.96Mn), Morgan Stanley (2.17Mn), Jpmorgan Chase & Co (2.02Mn) per Business Quant data.