Rhythm Pharmaceuticals, Inc. (RYTM) Ownership
RYTM ownership summary
as of October 17, 2026- Institutions
- 115.1% of shares outstanding
- Insiders
- 0.70% of shares outstanding
- Shares outstanding
- 68.6M
- Float
- 56.0M shares available to trade
- Short interest
- 15.76% 10.8M shares short
- Days to cover
- 16.33 short interest up 4.7% vs prior month
- Institutions 115.07%
- Insiders 0.70%
RYTM top institutional holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | RA Capital Management, LLC | 9.68% | 6.7M | $574.5M | — | June 30, 2026 |
| 2 | BlackRock Inc | 8.94% | 6.2M | $530.5M | −80,249 (−1.3%) | June 30, 2026 |
| 3 | Baker Bros Advisors LP | 8.14% | 5.6M | $482.9M | — | June 30, 2026 |
| 4 | PRIMECAP Management Company | 4.60% | 3.2M | $273.1M | −248,656 (−7.3%) | June 30, 2026 |
| 5 | Vanguard Portfolio Management, LLC | 4.56% | 3.1M | $270.3M | +96,177 (+3.2%) | June 30, 2026 |
| 6 | Vanguard Capital Management, LLC | 4.37% | 3.0M | $259.0M | +38,152 (+1.3%) | June 30, 2026 |
| 7 | JPMorgan Chase & Co | 3.85% | 2.7M | $228.6M | +1.1M (+70.7%) | June 30, 2026 |
| 8 | Perceptive Advisors LLC | 3.76% | 2.6M | $222.9M | +212,500 (+9.0%) | June 30, 2026 |
| 9 | State Street Corp | 3.74% | 2.6M | $221.8M | +301,678 (+13.3%) | June 30, 2026 |
| 10 | T. Rowe Price Associates, Inc. | 3.73% | 2.6M | $221.1M | +911,295 (+55.1%) | June 30, 2026 |
| 11 | Westfield Capital Management Company, L.P. | 3.21% | 2.2M | $190.3M | +279,472 (+14.5%) | June 30, 2026 |
| 12 | The Goldman Sachs Group Inc | 3.09% | 2.1M | $183.2M | +161,070 (+8.2%) | June 30, 2026 |
| 13 | Federated Hermes Inc | 2.59% | 1.8M | $153.9M | +499,413 (+38.8%) | June 30, 2026 |
| 14 | Polar Capital Holdings PLC | 2.42% | 1.7M | $143.4M | +48,046 (+3.0%) | June 30, 2026 |
| 15 | Geode Capital Management, LLC | 2.23% | 1.5M | $132.2M | +117,429 (+8.3%) | June 30, 2026 |
| 16 | Capital Research Global Investors | 2.23% | 1.5M | $132.0M | +416,843 (+37.4%) | June 30, 2026 |
| 17 | Citadel Advisors Llc | 1.84% | 1.3M | $108.9M | −154,967 (−10.9%) | June 30, 2026 |
| 18 | Checkpoint Capital LP | 1.72% | 1.2M | $102.2M | −41,200 (−3.4%) | June 30, 2026 |
| 19 | Siren, L.L.C. | 1.65% | 1.1M | $97.9M | +410,764 (+56.6%) | June 30, 2026 |
| 20 | Morgan Stanley - Brokerage Accounts | 1.62% | 1.1M | $95.8M | +408,262 (+58.0%) | June 30, 2026 |
Value at the latest close. Change = shares bought or sold in the latest quarterly filing (13F). In the top 20, 14 holders added 5.0M shares and 4 cut 525K.
RYTM top mutual fund and ETF holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Vanguard MStar Total Stk Mkt Idx Invest | 3.17% | 2.2M | $188.0M | −2,924 (−0.1%) | August 31, 2026 |
| 2 | PRIMECAP Odyssey Aggressive Growth | 2.89% | 2.0M | $171.3M | −136,120 (−6.4%) | June 30, 2026 |
| 3 | American Funds SMALLCAP World A | 2.48% | 1.7M | $147.1M | +587,121 (+52.4%) | June 30, 2026 |
| 4 | Vanguard Small Cap Index | 2.29% | 1.6M | $135.9M | +1,575 (+0.1%) | August 31, 2026 |
| 5 | Polar Capital Biotech S Inc | 2.29% | 1.6M | $135.8M | — | August 31, 2026 |
| 6 | iShares Russell 2000 ETF | 2.17% | 1.5M | $128.9M | −17,216 (−1.1%) | September 30, 2026 |
| 7 | State Street® SPDR® S&P® Biotech ETF | 1.73% | 1.2M | $102.7M | −22,700 (−1.9%) | September 30, 2026 |
| 8 | Federated Hermes Kaufmann R | 1.49% | 1.0M | $88.4M | +465,865 (+83.1%) | June 30, 2026 |
| 9 | PRIMECAP Odyssey Growth | 1.48% | 1.0M | $87.9M | −84,560 (−7.7%) | June 30, 2026 |
| 10 | Vanguard MStar Small Cap Growth Indx Inv | 1.31% | 905K | $78.0M | −6,936 (−0.8%) | August 31, 2026 |
| 11 | JPMorgan Mid Cap Growth I | 1.24% | 852K | $73.4M | +107,164 (+14.4%) | August 31, 2026 |
| 12 | JPMorgan Growth Advantage A | 1.22% | 839K | $72.3M | +190,292 (+29.4%) | August 31, 2026 |
| 13 | T. Rowe Price New Horizons | 1.03% | 710K | $61.2M | −29,019 (−3.9%) | August 31, 2026 |
| 14 | Federated Hermes Kaufmann Small Cap A | 0.89% | 610K | $52.6M | +18,000 (+3.0%) | June 30, 2026 |
| 15 | Fidelity Small Cap Index | 0.88% | 603K | $52.0M | +4,914 (+0.8%) | July 31, 2026 |
| 16 | Pictet-Biotech P USD | 0.83% | 568K | $49.0M | −2,304 (−0.4%) | June 30, 2026 |
| 17 | Vanguard Explorer Inv | 0.80% | 553K | $47.6M | +230,683 (+71.6%) | June 30, 2026 |
| 18 | iShares Russell 2000 Growth ETF | 0.79% | 541K | $46.6M | −685 (−0.1%) | September 30, 2026 |
| 19 | iShares Biotechnology ETF | 0.75% | 516K | $44.4M | −3,904 (−0.8%) | September 30, 2026 |
| 20 | Harbor Small Cap Growth Instl | 0.73% | 503K | $43.3M | +75,850 (+17.8%) | June 30, 2026 |
Funds report holdings monthly or quarterly; dates differ by fund.
RYTM insider transactions
latest 20| Date | Name | Transaction | Price | Shares | Value |
|---|---|---|---|---|---|
| 2026-03-04 | Christopher Paul German | Sell | $89.56 | 5,614 | $502,790 |
| 2026-02-19 | Hunter C Smith | Sell | $101.26 | 4,385 | $444,025 |
| 2026-02-17 | Hunter C Smith | Sell | $101.38 | 3,569 | $361,825 |
| 2026-02-12 | Hunter C Smith | Sell | $98.23 | 1,592 | $156,382 |
| 2026-02-11 | Hunter C Smith | Sell | $98.61 | 2,766 | $272,755 |
| 2026-02-10 | Hunter C Smith | Sell | $103.00 | 2,713 | $279,439 |
| 2026-02-05 | Hunter C Smith | Sell | $106.06 | 3,381 | $358,589 |
| 2026-02-04 | Hunter C Smith | Sell | $105.99 | 3,247 | $344,150 |
| 2025-12-11 | Pamela J Cramer | Sell | $111.00 | 3,350 | $371,850 |
| 2025-10-30 | Joseph Shulman | Sell | $115.24 | 9,748 | $1.1M |
| 2025-10-28 | Joseph Shulman | Sell | $115.01 | 2,815 | $323,753 |
| 2025-10-16 | Joseph Shulman | Sell | $112.03 | 14,437 | $1.6M |
| 2025-08-21 | Joseph Shulman | Sell | $100.07 | 4,188 | $419,093 |
| 2025-08-13 | Hunter C Smith | Sell | $96.00 | 3,477 | $333,792 |
| 2025-08-12 | Christopher Paul German | Sell | $95.00 | 1,500 | $142,500 |
| 2025-08-12 | Hunter C Smith | Sell | $96.33 | 24,611 | $2.4M |
| 2025-08-11 | Joseph Shulman | Sell | $90.08 | 3,984 | $358,879 |
| 2025-07-29 | Pamela J Cramer | Sell | $85.93 | 1,520 | $130,614 |
| 2025-07-09 | Christopher Paul German | Sell | $80.75 | 3,817 | $308,223 |
| 2025-07-09 | Hunter C Smith | Sell | $80.48 | 42,120 | $3.4M |
Reported trades by company officers, directors and other filers (including disclosures by members of Congress where EODHD lists them). "—" where the filing gives no share count.
RYTM shares outstanding
Year-end shares outstanding, adjusted for splits.
Who owns RYTM
Institutional investors own 115.1% of Rhythm Pharmaceuticals's shares and insiders 0.70%. The largest holder is RA Capital Management, LLC with 9.68% of the shares (6.7M), as of June 30, 2026. Among the top 20 institutions, 14 added shares and 4 reduced their stake in the latest filings. Short interest is 15.76% of the float, or 16.33 days of average trading volume. The share count rose 555.9% since 2014.
Related: RYTM analyst forecast, RYTM key metrics. See the RYTM stock overview for the latest quote and news.
RYTM ownership FAQ
Who owns the most Rhythm Pharmaceuticals stock?
The largest shareholders of Rhythm Pharmaceuticals are RA Capital Management, LLC (9.68%), BlackRock Inc (8.94%), Baker Bros Advisors LP (8.14%), PRIMECAP Management Company (4.60%), Vanguard Portfolio Management, LLC (4.56%).
What percentage of Rhythm Pharmaceuticals is owned by institutions?
Institutions hold 115.1% of Rhythm Pharmaceuticals's shares outstanding; insiders hold 0.70%.
Which funds own Rhythm Pharmaceuticals?
The largest fund holders of Rhythm Pharmaceuticals are Vanguard MStar Total Stk Mkt Idx Invest (3.17%), PRIMECAP Odyssey Aggressive Growth (2.89%), American Funds SMALLCAP World A (2.48%), Vanguard Small Cap Index (2.29%), Polar Capital Biotech S Inc (2.29%).
What is Rhythm Pharmaceuticals's short interest?
10.8M shares of Rhythm Pharmaceuticals were sold short, 15.76% of the float; at the average daily volume it would take 16.33 days to cover.
Are insiders buying or selling Rhythm Pharmaceuticals?
Of the latest 20 reported insider transactions in Rhythm Pharmaceuticals (since July 9, 2025), 0 were purchases and 20 were sales.
How many shares of Rhythm Pharmaceuticals are outstanding?
Rhythm Pharmaceuticals has 68.6M shares outstanding, of which 56.0M are in the public float.