RHYTHM PHARMACEUTICALS INC RYTM
COM · Common Stock · CUSIP 76243J105
Company in Boston, United States
- SectorHealth care
- IndustryPharmaceutical Preparations
- HeadquartersBoston, MA
- Founded2008
- Websiterhythmtx.com
- FilingsSEC EDGAR
* Summed across managers. Shares that two managers' reports both contain – a subsidiary's holdings that its parent's report includes too, or a sub-adviser's in its client's – are counted once ($608.3k this quarter). Holder counts are more reliable. Shares outstanding: 68.9m as of 2026-08-01, from the company's own SEC filing; the percentage can still exceed 100%: lent-out shares are counted by the lender and the buyer, and some reports overlap without saying so. Implied quarter-end price ≈ $110.72. Options: 5 managers hold calls ($17.6m notional), 6 hold puts ($11.5m).
Trends to Q2 2026
Institutional holders
Managers reporting a position, each quarter
Numbers
| Quarter | Holders |
|---|---|
| Q3 2022 | 101 |
| Q4 2022 | 116 |
| Q1 2023 | 127 |
| Q2 2023 | 117 |
| Q3 2023 | 145 |
| Q4 2023 | 170 |
| Q1 2024 | 169 |
| Q2 2024 | 167 |
| Q3 2024 | 178 |
| Q4 2024 | 205 |
| Q1 2025 | 230 |
| Q2 2025 | 229 |
| Q3 2025 | 266 |
| Q4 2025 | 282 |
| Q1 2026 | 286 |
| Q2 2026 | 305 |
Buyers vs sellers
Managers adding to or starting a position, vs cutting or selling out
Numbers
| Quarter | Bought or added | Cut or sold out |
|---|---|---|
| Q3 2024 | 88 | 74 |
| Q4 2024 | 105 | 77 |
| Q1 2025 | 129 | 87 |
| Q2 2025 | 124 | 107 |
| Q3 2025 | 155 | 98 |
| Q4 2025 | 154 | 129 |
| Q1 2026 | 156 | 142 |
| Q2 2026 | 166 | 141 |
Calls vs puts
Options held, notional value, last 4 quarters. P/C = puts ÷ calls
Numbers
| Quarter | Calls | Puts | P/C |
|---|---|---|---|
| Q3 2025 | $50.3m | $15.2m | 0.30 |
| Q4 2025 | $45.9m | $31.1m | 0.68 |
| Q1 2026 | $16.4m | $1.9m | 0.11 |
| Q2 2026 | $17.6m | $11.5m | 0.65 |
Biggest buyers
| JPMORGAN CHASE & CO | Added | +1.1m |
| PRICE T ROWE ASSOCIATES INC /MD/ | Added | +911.3k |
| FEDERATED HERMES, INC. | Added | +499.4k |
| Capital Research Global Investors | Added | +416.8k |
| Siren, L.L.C. | Added | +410.8k |
| MORGAN STANLEY | Added | +408.3k |
| Assenagon Asset Management S.A. | New | +373.0k |
| STATE STREET CORP | Added | +301.7k |
| Pictet Asset Management Holding SA | Added | +290.7k |
| WESTFIELD CAPITAL MANAGEMENT CO LP | Added | +279.5k |
Biggest sellers
| FMR LLC | Reduced | -663.8k |
| Point72 Asset Management, L.P. | Reduced | -432.6k |
| LORD, ABBETT & CO. LLC | Sold out | -349.0k |
| ADAGE CAPITAL PARTNERS GP, L.L.C. | Reduced | -328.7k |
| Logos Global Management LP | Reduced | -325.0k |
| Driehaus Capital Management LLC | Reduced | -307.3k |
| BANK OF AMERICA CORP /DE/ | Reduced | -303.2k |
| PRIMECAP MANAGEMENT CO/CA/ | Reduced | -248.7k |
| Hood River Capital Management LLC | Sold out | -239.9k |
| RENAISSANCE TECHNOLOGIES LLC | Reduced | -189.7k |
Biggest calls
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Added | $11.0m99.0k shares |
| CITADEL ADVISORS LLC | Reduced | $3.1m28.0k shares |
| JANE STREET GROUP, LLC | Reduced | $3.0m27.1k shares |
| IMC-Chicago, LLC | Reduced | $310.9k2.8k shares |
| SIMPLEX TRADING, LLC | Reduced | $155.4k1.4k shares |
Biggest puts
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Added | $5.4m48.3k shares |
| JANE STREET GROUP, LLC | Added | $2.7m24.0k shares |
| CITADEL ADVISORS LLC | Added | $1.9m17.5k shares |
| SIMPLEX TRADING, LLC | Added | $699.5k6.3k shares |
| IMC-Chicago, LLC | New | $621.8k5.6k shares |
| GROUP ONE TRADING LLC | New | $199.9k1.8k shares |
Options at notional value: the value of the shares the contracts control, as filers report them, not what the options cost. Not included in the holders, shares or buying above.
Major shareholders (over 5%)
Anyone who owns more than 5% of a class of the company's shares has to say so: on Schedule 13D if they may try to influence or control the company, on 13G if they're a passive investor, and update it as the stake changes. Each holder's latest filing, from 19 Dec 2024 on; percentages are of the share class, as the holder worked them out.
| Holder | Stake |
|---|---|
| RA CAPITAL MANAGEMENT, L.P. 13G · passive investor +1.2 pts · filed 2026-02-17 | 9.9% |
| BAKER BROS. ADVISORS LP 13G · institution filed 2025-05-15 | 8.9% |
| BlackRock, Inc. 13G · institution filed 2025-04-24 | 6.9% |
| PRIMECAP MANAGEMENT CO/CA/ 13G · institution -1.2 pts · filed 2026-02-12 | 5.2% |
| JPMORGAN CHASE & CO 13G · institution new · filed 2026-10-13 | 5.1% |
| PERCEPTIVE ADVISORS LLC 13G · passive investor -1.7 pts · filed 2026-05-15 | 5.1% |
| VANGUARD CAPITAL MANAGEMENT LLC 13G · institution new · filed 2026-04-30 | 5.0% |
Fell to 5% or below in the last year: VANGUARD GROUP INC (0.0%, 2026-03-27; now reported by VANGUARD CAPITAL MANAGEMENT LLC)
Insider purchases and sales since 1 Apr 2026
Shares bought or sold by the company's own officers, directors and 10% owners, in the open market or privately, as they reported to the SEC on Form 4 (due within two business days of the trade). Grants, option exercises, shares withheld for tax and gifts aren't included.
Officers and directors buying vs selling
Number of people, by quarter (10% owners not included)
Numbers
| Quarter | Buying | Bought | Selling | Sold | Sold under a plan |
|---|---|---|---|---|---|
| Q4 2024 | 0 | — | 3 | $5.9m | $5.9m |
| Q1 2025 | 0 | — | 7 | $6.3m | $5.7m |
| Q2 2025 | 0 | — | 6 | $12.4m | $12.4m |
| Q3 2025 | 0 | — | 5 | $11.1m | $11.1m |
| Q4 2025 | 0 | — | 2 | $6.1m | $6.1m |
| Q1 2026 | 0 | — | 2 | $2.7m | $2.2m |
| Q2 2026 | 0 | — | 2 | $4.1m | $3.7m |
| Q3 2026 | 0 | — | 6 | $28.8m | $28.8m |
| Date | Insider | Trade | Value |
|---|---|---|---|
| 2026-09-14 | Meeker David P President and CEO, director | Sold plan | $5.1m50.0k shares |
| 2026-08-31 | Smith Hunter C Chief Financial Officer | Sold plan | $6.6m62.8k shares |
| 2026-08-13 | Lee Jennifer Kayden EVP, Head of North America | Sold plan | $8.9m75.8k shares |
| 2026-08-13 | Garfield Alastair Chief Scientific Officer | Sold plan | $912.7k7.8k shares |
| 2026-08-13 | Shulman Joseph Chief Technical Officer | Sold plan | $608.2k5.1k shares |
| 2026-08-12 | Mazabraud Yann EVP, Head of International | Sold plan | $6.6m57.0k shares |
| 2026-06-22 | TETRAULT LYNN A. Director | Sold plan | $3.7m37.0k shares |
| 2026-05-15 | German Christopher Paul Corporate Controller & CAO | Sold | $428.1k4.6k shares |
Their holding: how much the trade added to or took from the insider's holding (direct, or the trust or fund named). The same trade is sometimes reported by more than one insider, such as a fund and the director who represents it; totals count it once. A value is left blank where the reported price is far from the market price (usually a typo).
Holders, Q2 2026
| Manager | Shares | Change |
|---|---|---|
| RA CAPITAL MANAGEMENT, L.P. 6.43% of their portfolio | 6.7m $740.2m | Unchanged |
| BlackRock, Inc. 0.01% of their portfolio | 6.2m $683.6m | Reduced -80.2k |
| BAKER BROS. ADVISORS LP 3.12% of their portfolio | 5.6m $622.3m | Unchanged |
| PRIMECAP MANAGEMENT CO/CA/ 0.21% of their portfolio | 3.2m $351.8m | Reduced -248.7k |
| VANGUARD PORTFOLIO MANAGEMENT LLC 0.02% of their portfolio | 3.1m $348.3m | Added +96.2k |
| VANGUARD CAPITAL MANAGEMENT LLC 0.01% of their portfolio | 3.0m $333.8m | Added +38.2k |
| JPMORGAN CHASE & CO 0.02% of their portfolio | 2.7m $292.2m | Added +1.1m |
| PERCEPTIVE ADVISORS LLC 4.46% of their portfolio | 2.6m $287.2m | Added +212.5k |
| STATE STREET CORP 0.01% of their portfolio | 2.6m $285.7m | Added +301.7k |
| PRICE T ROWE ASSOCIATES INC /MD/ 0.03% of their portfolio | 2.6m $284.9m | Added +911.3k |
| WESTFIELD CAPITAL MANAGEMENT CO LP 0.80% of their portfolio | 2.2m $245.2m | Added +279.5k |
| GOLDMAN SACHS GROUP INC 0.02% of their portfolio | 2.1m $236.1m | Added +161.1k |
| FEDERATED HERMES, INC. 0.29% of their portfolio | 1.8m $198.3m | Added +499.4k |
| Polar Capital Holdings Plc 0.52% of their portfolio | 1.7m $184.7m | Added +48.0k |
| GEODE CAPITAL MANAGEMENT, LLC 0.01% of their portfolio | 1.5m $170.3m | Added +117.4k |
| Capital Research Global Investors 0.02% of their portfolio | 1.5m $170.1m | Added +416.8k |
| CITADEL ADVISORS LLC 0.08% of their portfolio | 1.3m $140.3m | Reduced -155.0k |
| Checkpoint Capital L.P. 33.79% of their portfolio | 1.2m $131.7m | Reduced -41.2k |
| Siren, L.L.C. 2.56% of their portfolio | 1.1m $126.2m | Added +410.8k |
| MORGAN STANLEY 0.01% of their portfolio | 1.1m $123.5m | Added +408.3k |
| FMR LLC 0.00% of their portfolio | 1.0m $113.9m | Reduced -663.8k |
| Pictet Asset Management Holding SA 0.10% of their portfolio | 957.8k $106.3m | Added +290.7k |
| Jupiter Topco LLC 0.04% of their portfolio | 925.5k $102.8m | First filing |
| ALLIANCEBERNSTEIN L.P. 0.03% of their portfolio | 894.7k $77.8m | Reduced -15.7k |
| Woodline Partners LP 0.26% of their portfolio | 758.9k $84.3m | Unchanged |
| Clearbridge Investments, LLC 0.06% of their portfolio | 696.5k $77.3m | Added +87.0k |
| Rock Springs Capital Management LP 3.75% of their portfolio | 692.6k $76.9m | Added +2.9k |
| NORGES BANK 0.01% of their portfolio | 685.8k $76.1m | Not comparable |
| FRANKLIN RESOURCES INC 0.01% of their portfolio | 577.0k $64.1m | Reduced -49.8k |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.01% of their portfolio | 552.7k $61.4m | Added +26.3k |
| Integral Health Asset Management, LLC 2.51% of their portfolio | 550.0k $61.1m | Reduced -50.0k |
| Invesco Ltd. 0.00% of their portfolio | 543.3k $60.3m | Added +179.0k |
| NORTHERN TRUST CORP 0.01% of their portfolio | 540.3k $60.0m | Added +41.8k |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC 0.01% of their portfolio | 514.9k $57.2m | Reduced -26.6k |
| WELLINGTON MANAGEMENT GROUP LLP 0.01% of their portfolio | 488.7k $54.3m | Added +215.0k |
| VANGUARD FIDUCIARY TRUST CO 0.01% of their portfolio | 445.7k $49.5m | Added +23.8k |
| LOOMIS SAYLES & CO L P 0.06% of their portfolio | 434.1k $48.2m | Reduced -31.0k |
| Candriam S.C.A. 0.22% of their portfolio | 433.0k $48.0m | Reduced -31.3k |
| Squarepoint Ops LLC 0.09% of their portfolio | 422.9k $47.0m | Added +160.0k |
| Point72 Asset Management, L.P. 0.07% of their portfolio | 414.2k $46.0m | Reduced -432.6k |
| Sofinnova Investments, Inc. 2.42% of their portfolio | 408.0k $45.3m | Reduced -42.1k |
| AMERIPRISE FINANCIAL INC 0.01% of their portfolio | 401.6k $44.6m | Added +17.7k |
| ADAGE CAPITAL PARTNERS GP, L.L.C. 0.06% of their portfolio | 397.0k $44.1m | Reduced -328.7k |
| Bank of New York Mellon Corp 0.01% of their portfolio | 394.0k $43.8m | Added +100.7k |
| BRAIDWELL LP 1.57% of their portfolio | 381.1k $42.3m | Added +70.5k |
| Assenagon Asset Management S.A. 0.03% of their portfolio | 373.0k $41.4m | New |
| Artisan Partners Limited Partnership 0.06% of their portfolio | 354.8k $39.4m | Reduced -35.9k |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 325.5k $36.1m | Reduced -303.2k |
| ORBIMED ADVISORS LLC 0.68% of their portfolio | 322.9k $35.9m | Added +8.8k |
| MILLENNIUM MANAGEMENT LLC 0.02% of their portfolio | 316.7k $35.2m | Reduced -135.1k |
| SILVERARC CAPITAL MANAGEMENT, LLC 3.85% of their portfolio | 311.5k $34.6m | Added +5.5k |
| VOYA INVESTMENT MANAGEMENT LLC 0.03% of their portfolio | 273.0k $30.3m | Added +39.2k |
| Capital World Investors 0.00% of their portfolio | 221.4k $24.6m | Added +105.8k |
| Duquesne Family Office LLC 0.52% of their portfolio | 203.6k $22.6m | New |
| Nuveen, LLC 0.01% of their portfolio | 203.1k $22.5m | Added +85.7k |
| BNP PARIBAS FINANCIAL MARKETS 0.01% of their portfolio | 197.4k $21.9m | Reduced -50.5k |
| KENNEDY CAPITAL MANAGEMENT LLC 0.38% of their portfolio | 193.2k $21.5m | Added +127.4k |
| SCHRODER INVESTMENT MANAGEMENT GROUP 0.01% of their portfolio | 160.5k $17.7m | Added +28.8k |
| First Turn Management, LLC 1.83% of their portfolio | 154.0k $17.1m | New |
| NEW YORK STATE COMMON RETIREMENT FUND 0.02% of their portfolio | 148.2k $16.4m | Added +22.9k |
| UBS Group AG 0.00% of their portfolio | 144.4k $16.0m | Reduced -87.3k |
| Nicholas Investment Partners, LP 0.87% of their portfolio | 139.3k $15.5m | New |
| ADAR1 Capital Management, LLC 0.71% of their portfolio | 136.2k $15.1m | Reduced -75.3k |
| Connor, Clark & Lunn Investment Management Ltd. 0.03% of their portfolio | 135.9k $15.1m | Reduced -16.0k |
| Qube Research & Technologies Ltd 0.02% of their portfolio | 134.4k $14.9m | Reduced -143.5k |
| NEXTBio Capital Management LP 6.73% of their portfolio | 131.8k $14.6m | Added +5.7k |
| Driehaus Capital Management LLC 0.08% of their portfolio | 129.3k $14.4m | Reduced -307.3k |
| SummitTX Capital, L.P. 0.37% of their portfolio | 126.4k $14.0m | Reduced -39.2k |
| Logos Global Management LP 0.60% of their portfolio | 125.0k $13.9m | Reduced -325.0k |
| Opaleye Management Inc. 1.23% of their portfolio | 122.5k $13.6m | Reduced -500 |
| SEGALL BRYANT & HAMILL, LLC 0.16% of their portfolio | 121.9k $13.5m | New |
| DEUTSCHE BANK AG\ 0.00% of their portfolio | 115.2k $12.8m | Reduced -26.4k |
| Longaeva Partners L.P. 0.35% of their portfolio | 110.1k $12.2m | New |
| Swiss National Bank 0.01% of their portfolio | 109.7k $12.2m | Reduced -2.5k |
| PFM Health Sciences, LP 0.98% of their portfolio | 101.5k $11.3m | Reduced -35.1k |
| Aberdeen Group plc 0.01% of their portfolio | 94.9k $10.5m | Added +15.6k |
| AXIOM INVESTORS LLC /DE 0.08% of their portfolio | 86.9k $9.6m | Reduced -4.9k |
| Russell Investments Group, Ltd. 0.01% of their portfolio | 86.7k $9.6m | Reduced -29.0k |
| First Light Asset Management, LLC 0.58% of their portfolio | 85.8k $9.5m | Reduced -1.4k |
| ALGERT GLOBAL LLC 0.11% of their portfolio | 83.4k $9.3m | Added +24.9k |
| Granahan Investment Management, LLC 0.33% of their portfolio | 83.3k $9.2m | Added +5.6k |
| NEUBERGER BERMAN GROUP LLC 0.01% of their portfolio | 83.0k $9.2m | Added +9.6k |
| WCM INVESTMENT MANAGEMENT, LLC 0.02% of their portfolio | 80.6k $8.9m | Reduced -68 |
| SPHERA FUNDS MANAGEMENT LTD. 1.28% of their portfolio | 80.4k $8.9m | New |
| Atom Investors LP 0.73% of their portfolio | 73.5k $8.2m | Added +16.5k |
| SILVERCREST ASSET MANAGEMENT GROUP LLC 0.05% of their portfolio | 73.4k $8.2m | Added +26.5k |
| RHUMBLINE ADVISERS 0.01% of their portfolio | 73.3k $8.1m | Added +3.5k |
| WELLS FARGO & COMPANY/MN 0.00% of their portfolio | 72.1k $8.0m | Added +38.0k |
| PRUDENTIAL FINANCIAL INC 0.01% of their portfolio | 69.1k $7.7m | Added +39.0k |
| CAPITAL FUND MANAGEMENT S.A. 0.05% of their portfolio | 68.5k $7.6m | New |
| RENAISSANCE TECHNOLOGIES LLC 0.01% of their portfolio | 68.3k $7.6m | Reduced -189.7k |
| PICTON MAHONEY ASSET MANAGEMENT 0.07% of their portfolio | 65.9k $7.3m | Added +15.5k |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM 0.01% of their portfolio | 64.0k $7.1m | Reduced -1.8k |
| Blue Owl Capital Holdings LP 1.04% of their portfolio | 61.5k $6.8m | Unchanged |
| ExodusPoint Capital Management, LP 0.06% of their portfolio | 61.1k $6.8m | Added +43.4k |
| AQR CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 59.2k $6.6m | Reduced -71 |
| CITIGROUP INC 0.00% of their portfolio | 58.3k $6.5m | Added +46.0k |
| RAYMOND JAMES FINANCIAL INC 0.00% of their portfolio | 58.1k $6.4m | Added +8.1k |
| MANUFACTURERS LIFE INSURANCE COMPANY, THE 0.00% of their portfolio | 57.2k $6.3m | Added +6.4k |
| Trexquant Investment LP 0.04% of their portfolio | 56.2k $6.2m | New |