Alkermes plc. (ALKS) Institutional Ownership

Ownership Summary

The institutional landscape for Alkermes plc. (NASDAQ:ALKS) includes 351 filers as of the latest reporting cycle ending September 2025.

• The collective stake of institutional investors in Alkermes moved to 100.6% in September 2025, a shift down from the 100.9% reported for June 2025.
• The company experienced a 2.44% quarterly change in institutional shares held, alongside an increase of 4.78% in total owners annually.
• Among the 351 institutional holders of Alkermes, 192 added to their stakes while 128 trimmed their positions and 31 held steady.
• The aggregate institutional position in Alkermes now stands at 169.91Mn shares as of September 2025, after investors increased their holdings (up by 4.04Mn shares quarter on quarter which is down 8.28Mn shares year over year).
• As of September 30, 2025, BlackRock, Inc. held Alkermes's largest shareholding position with over 27.97Mn shares, representing 16.56% of total outstanding shares.
• Among the most significant buyers of Alkermes during September 2025 were BAKER BROS. ADVISORS LP (1.68Mn), ARROWSTREET CAPITAL, LIMITED PARTNERSHIP (1.11Mn), VIRGINIA RETIREMENT SYSTEMS ET Al (901.33K), AMERICAN CENTURY COMPANIES INC (740.25K), CITADEL ADVISORS LLC (704.83K).
• Leading sellers of Alkermes stock in September 2025 included RTW INVESTMENTS, LP (3.01Mn), WELLINGTON MANAGEMENT GROUP LLP (1.32Mn), BANK OF AMERICA CORP /DE/ (1.06Mn), JPMORGAN CHASE & CO (908.12K), FARALLON CAPITAL MANAGEMENT LLC (670.86K).
• The top 10 institutional holders of Alkermes for the quarter ending September 2025 included BlackRock, Inc. (27.97Mn), VANGUARD GROUP INC (18.18Mn), PRICE T ROWE ASSOCIATES INC /MD/ (10.24Mn), STATE STREET CORP (8.54Mn), BAKER BROS. ADVISORS LP (8.09Mn), RENAISSANCE TECHNOLOGIES LLC (6.29Mn), AMERICAN CENTURY COMPANIES INC (4.40Mn), GEODE CAPITAL MANAGEMENT, LLC (4.06Mn), JPMORGAN CHASE & CO (3.93Mn), DIMENSIONAL FUND ADVISORS LP (3.70Mn).