Ranked by reported Q1 2026 13F market value
Share of total reported institutional value in RYTM held by the largest 10 / 25 filers.
| # | Institution | Shares Held | Market Value | QoQ Change | Ownership % | % of Fund |
|---|---|---|---|---|---|---|
| 1 | RA CAPITAL MANAGEMENT, L.P. | 6.7M | $579.8M | 0.0% | 9.728% | 6.14% |
| 2 | BlackRock, Inc. | 6.2M | $542.4M | -1.0% | 9.101% | 0.01% |
| 3 | BAKER BROS. ADVISORS LP | 5.6M | $487.4M | 0.0% | 8.178% | 2.80% |
| 4 | PRIMECAP MANAGEMENT CO/CA/ | 3.4M | $297.2M | -1.8% | 4.987% | 0.23% |
| 5 | VANGUARD PORTFOLIO MANAGEMENT LLC | 3.0M | $264.5M | — | 4.437% | 0.01% |
| 6 | VANGUARD CAPITAL MANAGEMENT LLC | 3.0M | $258.1M | — | 4.331% | 0.01% |
| 7 | PERCEPTIVE ADVISORS LLC | 2.4M | $206.4M | -6.8% | 3.464% | 4.08% |
| 8 | STATE STREET CORP | 2.3M | $197.6M | +3.3% | 3.315% | 0.01% |
| 9 | GOLDMAN SACHS GROUP INC | 2.0M | $170.9M | +7.3% | 2.868% | 0.02% |
| 10 | WESTFIELD CAPITAL MANAGEMENT CO LP | 1.9M | $167.8M | +52.2% | 2.815% | 0.70% |
| 11 | FMR LLC | 1.7M | $147.0M | -1.0% | 2.466% | 0.01% |
| 12 | Polar Capital Holdings Plc | 1.6M | $140.5M | +36.3% | 2.357% | 0.50% |
| 13 | CITADEL ADVISORS LLC | 1.5M | $126.4M | +659.9% | 2.120% | 0.06% |
| 14 | GEODE CAPITAL MANAGEMENT, LLC | 1.4M | $123.2M | +2.9% | 2.067% | 0.01% |
| 15 | FEDERATED HERMES, INC. | 1.3M | $111.9M | -20.8% | 1.877% | 0.18% |
| 16 | Checkpoint Capital L.P. | 1.2M | $106.7M | +23.7% | 1.791% | 38.30% |
| 17 | ALLIANCEBERNSTEIN L.P. | 910K | $97.5M | -2.1% | 1.328% | 0.03% |
| 18 | Capital Research Global Investors | 1.1M | $97.0M | +13.2% | 1.628% | 0.02% |
| 19 | JANUS HENDERSON GROUP PLC | 918K | $79.9M | -18.5% | 1.340% | 0.04% |
| 20 | Point72 Asset Management, L.P. | 847K | $73.6M | +97.2% | 1.236% | 0.10% |
| 21 | Woodline Partners LP | 759K | $66.0M | +10.2% | 1.107% | 0.25% |
| 22 | ADAGE CAPITAL PARTNERS GP, L.L.C. | 726K | $63.1M | +16.8% | 1.059% | 0.10% |
| 23 | Siren, L.L.C. | 726K | $63.1M | +45.1% | 1.059% | 1.75% |
| 24 | MORGAN STANLEY | 704K | $61.2M | +8.1% | 1.027% | 0.00% |
| 25 | Rock Springs Capital Management LP | 690K | $60.0M | -0.8% | 1.006% | 3.54% |
denotes a marquee investor (Buffett, Burry, ARK, Tiger Global, Pershing Square, Baupost and other widely-followed managers). “% of Fund” shows how much of that investor’s total 13F portfolio is invested in RYTM — a direct measure of their conviction.
Filings activity in RYTM during Q1 2026, grouped by how each filer changed its position.
8 quarters of 13F filings · Δ columns show change vs prior quarter
| Quarter | Inst. Holders | Δ Holders | Ownership % | Δ Ownership | Total 13F Value | Δ Value |
|---|---|---|---|---|---|---|
| Q1 2026 | 282 | +2.5% | 101.14% | 24.13 pp | $6.13B | 19% |
| Q4 2025 | 275 | +6.6% | 125.27% | +9.55 pp | $7.59B | +8.3% |
| Q3 2025 | 258 | +15% | 115.72% | +49.12 pp | $7.01B | +74% |
| Q2 2025 | 225 | 0.4% | 66.60% | +12.22 pp | $4.03B | +22% |
| Q1 2025 | 226 | +11% | 54.38% | 3.98 pp | $3.29B | 6.8% |
| Q4 2024 | 203 | +16% | 58.36% | +0.97 pp | $3.53B | +1.7% |
| Q3 2024 | 175 | +7.4% | 57.39% | +11.07 pp | $3.48B | +24% |
| Q2 2024 | 163 | — | 46.32% | — | $2.81B | — |
Source: SEC 13F institutional filings. Ownership % requires market cap data and will show once linked. Δ columns compare to the immediately prior filed quarter.
Quick answers to the most common questions about buying RYTM stock.
Based on Q1 2026 13F filings, institutional ownership of Rhythm Pharmaceuticals, Inc. stands at 101.1%, held across 282 reporting institutions.
RA CAPITAL MANAGEMENT, L.P. is the largest reported institutional holder of RYTM, with approximately 6,666,837 shares worth $0.58B as of Q1 2026.
Yes — 2 widely-followed marquee investors appear among the top 25 institutional holders of RYTM, including CITADEL ADVISORS LLC, Point72 Asset Management, L.P..
Our composite Smart Money Score for RYTM is 46 out of 100 (Neutral). It combines net institutional buying activity, ownership shift, marquee investor presence, and holder-count growth.
63 institutions opened new positions in RYTM during Q1 2026, while 56 fully exited. 58 added to existing positions and 159 trimmed.
RYTM institutional ownership fell by 24.13 percentage points quarter-over-quarter, with a net change of +7 holders.
The top 10 institutions account for 51.8% of all reported 13F value in RYTM, and the top 25 account for 74.9%.
All data is sourced from SEC Form 13F filings, which institutional investment managers with at least $100M in assets are required to file each quarter. We process every 13F filing from EDGAR and recompute the aggregates after each cycle. Insider transactions are sourced from Form 4 filings.
Rhythm Pharmaceuticals, Inc. (RYTM) Institutional Ownership