Rhythm Pharmaceuticals, Inc. (RYTM) Institutional Ownership

Ownership Summary

Rhythm Pharmaceuticals, Inc. (NASDAQ:RYTM) has 271 institutional investors with active 13F positions as of December 2025.

• Their combined ownership stood at 108.5% of outstanding shares in December 2025, down from 738.0% in September 2025.
• They decreased total shares held in Rhythm Pharmaceuticals by -85.19% from last quarter, and the number of investors in RYTM increased 33.5% annually.
• Activity in RYTM broke down as 155 buyers, 90 sellers, and 26 unchanged among 271 total holders.
• Altogether, these fund groups held 71.88Mn shares in RYTM by December 2025, down by 413.61Mn shares quarter on quarter, and up 6.14Mn shares year over year.
• As of December 31, 2025, the biggest holder of Rhythm Pharmaceuticals is RA CAPITAL MANAGEMENT, L.P. at 6.67Mn shares, representing 10.06% of shares outstanding.
• The biggest buyers of Rhythm Pharmaceuticals for the quarter ending December 2025 included VANGUARD PORTFOLIO MANAGEMENT LLC (3.04Mn), VANGUARD CAPITAL MANAGEMENT LLC (2.97Mn), PRICE T ROWE ASSOCIATES INC /MD/ (1.65Mn), CITADEL ADVISORS LLC (1.27Mn), Janus Henderson Group Plc (710.18K).
• The largest sellers of Rhythm Pharmaceuticals for the quarter ending December 2025 were Goldman Sachs Group Inc (1.7Mn), DRIEHAUS CAPITAL MANAGEMENT LLC (848.68K), Opaleye Management Inc. (537.0K), Rockefeller Capital Management L.P. (459.82K), Federated Hermes, Inc. (337.54K).
• According to Business Quant data, leading holders of RYTM for December 2025 are RA CAPITAL MANAGEMENT, L.P. (6.67Mn), BlackRock, Inc. (6.24Mn), BAKER BROS. ADVISORS LP (5.6Mn), PRIMECAP MANAGEMENT CO/CA/ (3.42Mn), VANGUARD PORTFOLIO MANAGEMENT LLC (3.04Mn), VANGUARD CAPITAL MANAGEMENT LLC (2.97Mn), PERCEPTIVE ADVISORS LLC (2.37Mn), State Street Corp (2.27Mn), Goldman Sachs Group Inc (1.97Mn), WESTFIELD CAPITAL MANAGEMENT CO LP (1.93Mn).