Alnylam Pharmaceuticals, Inc. (ALNY) Institutional Ownership

Ownership Summary

Recent 13F filings as of September 2025 show that 806 institutional investors hold a position in Alnylam Pharmaceuticals, Inc. (NASDAQ:ALNY).

• The percentage of Alnylam Pharmaceuticals owned by institutions changed from 102.3% in June 2025 to 102.1% in September 2025, marking a slight down trend.
• Quarterly data indicates a 0.03% shift in institutional share volume, and the annual owner count reflects an increase of 42.91%.
• Among the 806 institutional holders of Alnylam Pharmaceuticals, 432 added to their stakes while 288 trimmed their positions and 86 held steady.
• Collectively, institutional investors increased their stake in Alnylam Pharmaceuticals to 133.87Mn shares as of September 2025, a change that is up by 43.81K shares quarter on quarter and up 7.90Mn shares year over year.
• The top institutional stake in Alnylam Pharmaceuticals as of September 30, 2025 belongs to FMR LLC, which owns 16.77Mn shares, or 12.79% of the company.
• Among the most significant buyers of Alnylam Pharmaceuticals during September 2025 were GROUPAMA ASSET MANAGMENT (2.48Mn), JPMORGAN CHASE & CO (2.48Mn), ARROWSTREET CAPITAL, LIMITED PARTNERSHIP (1.19Mn), JANE STREET GROUP, LLC (974.89K), FMR LLC (961.10K).
• Leading sellers of Alnylam Pharmaceuticals stock in September 2025 included REGENERON PHARMACEUTICALS, INC. (3.05Mn), T. Rowe Price Investment Management, Inc. (2.11Mn), Capital International Investors (1.42Mn), PRICE T ROWE ASSOCIATES INC /MD/ (1.34Mn), Winslow Capital Management, LLC (1.18Mn).
• The top 10 institutional holders of Alnylam Pharmaceuticals for the quarter ending September 2025 included FMR LLC (16.77Mn), Capital World Investors (16.43Mn), VANGUARD GROUP INC (13.57Mn), BlackRock, Inc. (9.90Mn), Capital Research Global Investors (7.22Mn), JPMORGAN CHASE & CO (4.54Mn), GROUPAMA ASSET MANAGMENT (4.03Mn), STATE STREET CORP (3.08Mn), BAILLIE GIFFORD & CO (2.79Mn), GEODE CAPITAL MANAGEMENT, LLC (2.50Mn).