Castle Biosciences Inc (CSTL) Institutional Ownership

Ownership Summary

Castle Biosciences Inc (NASDAQ:CSTL) currently has 172 active institutional owners and shareholders as of today (September 2025), that have filed 13F forms with the Securities Exchange Commission (SEC).

• Castle Biosciences saw its institutional ownership percentage rose to 91.5% in September 2025 from 88.7% in June 2025.
• Quarterly data indicates a 2.67% shift in institutional share volume, and the annual owner count reflects a decrease of 7.03%.
• A review of institutional activity for Castle Biosciences shows 84 of 172 filers increasing their positions, while 65 reduced their stake, and 23 remained unchanged.
• The total number of shares held by institutions in Castle Biosciences increased to 26.54Mn as of September 2025, a net change of up by 690.88K shares quarter on quarter, and up 619.23K shares year over year.
• As of September 30, 2025, BlackRock, Inc. held Castle Biosciences's largest shareholding position with over 3.19Mn shares, representing 11.00% of total outstanding shares.
• Among the most significant buyers of Castle Biosciences during September 2025 were AIGH Capital Management LLC (707.29K), SUMMIT PARTNERS PUBLIC ASSET MANAGEMENT, LLC (400.00K), Connor, Clark & Lunn Investment Management Ltd. (209.46K), MILLENNIUM MANAGEMENT LLC (146.69K), BRIDGEWAY CAPITAL MANAGEMENT, LLC (136.43K).
• Leading sellers of Castle Biosciences stock in September 2025 included WASATCH ADVISORS LP (380.65K), Cubist Systematic Strategies, LLC (187.39K), SCHRODER INVESTMENT MANAGEMENT GROUP (153.62K), Trexquant Investment LP (139.63K), ALGERT GLOBAL LLC (127.29K).
• The top 10 institutional holders of Castle Biosciences for the quarter ending September 2025 included BlackRock, Inc. (3.19Mn), VANGUARD GROUP INC (2.17Mn), PRINCIPAL FINANCIAL GROUP INC (1.79Mn), Portolan Capital Management, LLC (1.52Mn), DIMENSIONAL FUND ADVISORS LP (1.47Mn), Nuveen, LLC (957.08K), BRAIDWELL LP (822.74K), STATE STREET CORP (724.08K), AIGH Capital Management LLC (707.29K), GEODE CAPITAL MANAGEMENT, LLC (698.61K).