Who owns Rhythm Pharmaceuticals (RYTM)
Which tracked institutional funds hold RYTM, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See RYTM company fundamentals →
Ownership as of the 2026-Q2 13F filings (latest filed 2026-09-22). 13F is disclosed up to 45 days after quarter-end, so the most recent quarter fills in over the following weeks.
How the tape is positioned
132 tracked funds added or opened RYTM while 51 trimmed or exited it between 2026-Q1 and 2026-Q2 — the tape is split. When large holders disagree on a name, the funds moving first are sometimes ahead of the story.
A prompt to read the filings, not a verdict. 13F is a quarter-end snapshot disclosed up to 45 days late; a fund adds or exits for mandate, benchmark, and timing reasons that have nothing to do with a view on the stock. This is a starting question, not a signal to trade.
Conviction spread
RYTM’s largest tracked holder by dollar value, RA CAPITAL MANAGEMENT, L.P., sizes it at 6.4% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 6.4pp conviction gap — its largest holder concentrates the name more heavily than the typical one.
Book-share is each fund’s reported value in RYTM divided by its whole reported 13F book, so it is comparable across funds of different sizes and is unaffected by stock splits. A higher share means a fund has committed more of its book to the name — a starting question about conviction, not a verdict or a signal to trade.
Institutional & insider positioning
Between 2026-Q1 and 2026-Q2, across 288 tracked filers holding RYTM, 165 increased or opened the position and 153 reduced or closed it; over the same quarter, open-market insider Form 4s were net sales.
This fuses two public signals for the same quarter — how tracked institutions changed their positions and whether insiders bought or sold in the open market. It describes what was filed; it is a starting question, not a verdict or a signal to trade.
New buyers & exits
Funds opening or closing a position in RYTM between the 2026-Q1 and 2026-Q2 13F filings, and the largest changes among funds holding it in both. New buyers and exits are counted on fund presence (split-invariant); adds and trims are measured on reported value.
New buyers 23
- Jupiter Topco LLC$103M
- Duquesne Family Office LLC$23M
- Assenagon Asset Management S.A.$21M
- First Turn Management, LLC$17M
- Nicholas Investment Partners, LP$15M
- SEGALL BRYANT & HAMILL, LLC$14M
Full exits 22
- JANUS HENDERSON GROUP PLC$80M
- LORD, ABBETT & CO. LLC$30M
- Hood River Capital Management LLC$21M
- M&G PLC$12M
- BALYASNY ASSET MANAGEMENT L.P.$5M
- CASTLEARK MANAGEMENT LLC$5M
Largest adds
- BlackRock, Inc.$327M
- JPMORGAN CHASE & CO$172M
- RA CAPITAL MANAGEMENT, L.P.$160M
- PRICE T ROWE ASSOCIATES INC /MD/$141M
- BAKER BROS. ADVISORS LP$135M
- STATE STREET CORP$88M
Largest trims
- FMR LLC$30M
- Point72 Asset Management, L.P.$28M
- Logos Global Management LP$25M
- Driehaus Capital Management LLC$24M
- Opaleye Management Inc.$22M
- ALLIANCEBERNSTEIN L.P.$20M
Institutional holders
One row per tracked fund, most shares held first (every row is from one quarter; reported value breaks ties). “% of value” is the fund’s share of this security’s tracked institutional value — not of shares outstanding.
| Fund | Shares | Reported value | % of value | Quarter |
|---|---|---|---|---|
| RA CAPITAL MANAGEMENT, L.P. | 6,666,837 | $740M | 8.9% | 2026-Q2 |
| BlackRock, Inc. added | 6,156,902 | $684M | 8.2% | 2026-Q2 |
| BAKER BROS. ADVISORS LP | 5,604,483 | $622M | 7.4% | 2026-Q2 |
| PRIMECAP MANAGEMENT CO/CA/ trimmed | 3,168,853 | $352M | 4.2% | 2026-Q2 |
| VANGUARD PORTFOLIO MANAGEMENT LLC added | 3,136,895 | $348M | 4.2% | 2026-Q2 |
| VANGUARD CAPITAL MANAGEMENT LLC added | 3,005,977 | $334M | 4.0% | 2026-Q2 |
| JPMORGAN CHASE & CO added | 2,652,746 | $292M | 3.5% | 2026-Q2 |
| PERCEPTIVE ADVISORS LLC added | 2,586,295 | $287M | 3.4% | 2026-Q2 |
| STATE STREET CORP added | 2,573,529 | $286M | 3.4% | 2026-Q2 |
| PRICE T ROWE ASSOCIATES INC /MD/ added | 2,566,171 | $285M | 3.4% | 2026-Q2 |
| WESTFIELD CAPITAL MANAGEMENT CO LP added | 2,208,595 | $245M | 2.9% | 2026-Q2 |
| GOLDMAN SACHS GROUP INC added | 2,126,502 | $236M | 2.8% | 2026-Q2 |
| FEDERATED HERMES, INC. added | 1,785,716 | $198M | 2.4% | 2026-Q2 |
| Polar Capital Holdings Plc added | 1,663,632 | $185M | 2.2% | 2026-Q2 |
| GEODE CAPITAL MANAGEMENT, LLC added | 1,533,698 | $170M | 2.0% | 2026-Q2 |
| Capital Research Global Investors added | 1,532,303 | $170M | 2.0% | 2026-Q2 |
| CITADEL ADVISORS LLC trimmed | 1,263,652 | $140M | 1.7% | 2026-Q2 |
| Checkpoint Capital L.P. trimmed | 1,186,000 | $132M | 1.6% | 2026-Q2 |
| Siren, L.L.C. added | 1,136,275 | $126M | 1.5% | 2026-Q2 |
| MORGAN STANLEY added | 1,112,240 | $123M | 1.5% | 2026-Q2 |
| FMR LLC trimmed | 1,025,840 | $114M | 1.4% | 2026-Q2 |
| Pictet Asset Management Holding SA added | 957,785 | $106M | 1.3% | 2026-Q2 |
| Jupiter Topco LLC new | 925,490 | $103M | 1.2% | 2026-Q2 |
| ALLIANCEBERNSTEIN L.P. trimmed | 894,723 | $78M | 0.9% | 2026-Q2 |
| Woodline Partners LP | 758,891 | $84M | 1.0% | 2026-Q2 |
| Clearbridge Investments, LLC added | 696,473 | $77M | 0.9% | 2026-Q2 |
| Rock Springs Capital Management LP added | 692,598 | $77M | 0.9% | 2026-Q2 |
| NORGES BANK added | 685,844 | $76M | 0.9% | 2026-Q2 |
| FRANKLIN RESOURCES INC trimmed | 577,033 | $64M | 0.8% | 2026-Q2 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC added | 552,738 | $61M | 0.7% | 2026-Q2 |
| Integral Health Asset Management, LLC trimmed | 550,000 | $61M | 0.7% | 2026-Q2 |
| Invesco Ltd. added | 543,271 | $60M | 0.7% | 2026-Q2 |
| NORTHERN TRUST CORP added | 540,332 | $60M | 0.7% | 2026-Q2 |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC trimmed | 514,850 | $57M | 0.7% | 2026-Q2 |
| WELLINGTON MANAGEMENT GROUP LLP added | 488,747 | $54M | 0.6% | 2026-Q2 |
| VANGUARD FIDUCIARY TRUST CO added | 445,723 | $49M | 0.6% | 2026-Q2 |
| LOOMIS SAYLES & CO L P trimmed | 434,102 | $48M | 0.6% | 2026-Q2 |
| Candriam S.C.A. trimmed | 433,025 | $48M | 0.6% | 2026-Q2 |
| Squarepoint Ops LLC added | 422,921 | $47M | 0.6% | 2026-Q2 |
| Point72 Asset Management, L.P. trimmed | 414,210 | $46M | 0.6% | 2026-Q2 |
| Sofinnova Investments, Inc. trimmed | 408,027 | $45M | 0.5% | 2026-Q2 |
| AMERIPRISE FINANCIAL INC added | 401,634 | $45M | 0.5% | 2026-Q2 |
| ADAGE CAPITAL PARTNERS GP, L.L.C. trimmed | 397,000 | $44M | 0.5% | 2026-Q2 |
| Bank of New York Mellon Corp added | 394,044 | $44M | 0.5% | 2026-Q2 |
| BRAIDWELL LP added | 381,128 | $42M | 0.5% | 2026-Q2 |
| Artisan Partners Limited Partnership trimmed | 354,816 | $39M | 0.5% | 2026-Q2 |
| BANK OF AMERICA CORP /DE/ trimmed | 325,470 | $36M | 0.4% | 2026-Q2 |
| ORBIMED ADVISORS LLC added | 322,900 | $36M | 0.4% | 2026-Q2 |
| MILLENNIUM MANAGEMENT LLC trimmed | 316,719 | $35M | 0.4% | 2026-Q2 |
| SILVERARC CAPITAL MANAGEMENT, LLC added | 311,461 | $35M | 0.4% | 2026-Q2 |
| VOYA INVESTMENT MANAGEMENT LLC added | 272,974 | $30M | 0.4% | 2026-Q2 |
| Capital World Investors added | 221,450 | $25M | 0.3% | 2026-Q2 |
| Duquesne Family Office LLC new | 203,618 | $23M | 0.3% | 2026-Q2 |
| Nuveen, LLC added | 203,078 | $23M | 0.3% | 2026-Q2 |
| BNP PARIBAS FINANCIAL MARKETS trimmed | 197,374 | $22M | 0.3% | 2026-Q2 |
| KENNEDY CAPITAL MANAGEMENT LLC added | 193,215 | $21M | 0.3% | 2026-Q2 |
| Assenagon Asset Management S.A. trimmed | 186,491 | $21M | 0.2% | 2026-Q2 |
| SCHRODER INVESTMENT MANAGEMENT GROUP added | 160,518 | $18M | 0.2% | 2026-Q2 |
| First Turn Management, LLC added | 154,018 | $17M | 0.2% | 2026-Q2 |
| NEW YORK STATE COMMON RETIREMENT FUND added | 148,152 | $16M | 0.2% | 2026-Q2 |
| UBS Group AG trimmed | 144,378 | $16M | 0.2% | 2026-Q2 |
| Nicholas Investment Partners, LP added | 139,270 | $15M | 0.2% | 2026-Q2 |
| ADAR1 Capital Management, LLC trimmed | 136,158 | $15M | 0.2% | 2026-Q2 |
| Connor, Clark & Lunn Investment Management Ltd. trimmed | 135,867 | $15M | 0.2% | 2026-Q2 |
| Qube Research & Technologies Ltd trimmed | 134,410 | $15M | 0.2% | 2026-Q2 |
| NEXTBio Capital Management LP added | 131,758 | $15M | 0.2% | 2026-Q2 |
| Driehaus Capital Management LLC trimmed | 129,285 | $14M | 0.2% | 2026-Q2 |
| SummitTX Capital, L.P. trimmed | 126,401 | $14M | 0.2% | 2026-Q2 |
| Logos Global Management LP trimmed | 125,000 | $14M | 0.2% | 2026-Q2 |
| Opaleye Management Inc. trimmed | 122,500 | $14M | 0.2% | 2026-Q2 |
| SEGALL BRYANT & HAMILL, LLC new | 121,866 | $14M | 0.2% | 2026-Q2 |
| DEUTSCHE BANK AG\ trimmed | 115,232 | $13M | 0.2% | 2026-Q2 |
| Longaeva Partners L.P. new | 110,074 | $12M | 0.1% | 2026-Q2 |
| Swiss National Bank trimmed | 109,700 | $12M | 0.1% | 2026-Q2 |
| PFM Health Sciences, LP trimmed | 101,550 | $11M | 0.1% | 2026-Q2 |
| Aberdeen Group plc added | 94,946 | $11M | 0.1% | 2026-Q2 |
| AXIOM INVESTORS LLC /DE trimmed | 86,880 | $10M | 0.1% | 2026-Q2 |
| Russell Investments Group, Ltd. trimmed | 86,709 | $10M | 0.1% | 2026-Q2 |
| First Light Asset Management, LLC trimmed | 85,765 | $10M | 0.1% | 2026-Q2 |
| ALGERT GLOBAL LLC added | 83,431 | $9M | 0.1% | 2026-Q2 |
| Granahan Investment Management, LLC added | 83,270 | $9M | 0.1% | 2026-Q2 |
| NEUBERGER BERMAN GROUP LLC added | 83,035 | $9M | 0.1% | 2026-Q2 |
| WCM INVESTMENT MANAGEMENT, LLC trimmed | 80,552 | $9M | 0.1% | 2026-Q2 |
| SPHERA FUNDS MANAGEMENT LTD. new | 80,400 | $9M | 0.1% | 2026-Q2 |
| Atom Investors LP added | 73,465 | $8M | 0.1% | 2026-Q2 |
| SILVERCREST ASSET MANAGEMENT GROUP LLC added | 73,432 | $8M | 0.1% | 2026-Q2 |
| RHUMBLINE ADVISERS added | 73,333 | $8M | 0.1% | 2026-Q2 |
| WELLS FARGO & COMPANY/MN added | 72,147 | $8M | 0.1% | 2026-Q2 |
| PRUDENTIAL FINANCIAL INC added | 69,145 | $8M | 0.1% | 2026-Q2 |
| CAPITAL FUND MANAGEMENT S.A. new | 68,548 | $8M | 0.1% | 2026-Q2 |
| RENAISSANCE TECHNOLOGIES LLC trimmed | 68,281 | $8M | 0.1% | 2026-Q2 |
| PICTON MAHONEY ASSET MANAGEMENT added | 65,880 | $7M | 0.1% | 2026-Q2 |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM trimmed | 64,031 | $7M | 0.1% | 2026-Q2 |
| Blue Owl Capital Holdings LP | 61,455 | $7M | 0.1% | 2026-Q2 |
| ExodusPoint Capital Management, LP added | 61,147 | $7M | 0.1% | 2026-Q2 |
| AQR CAPITAL MANAGEMENT LLC added | 59,208 | $7M | 0.1% | 2026-Q2 |
| CITIGROUP INC added | 58,347 | $6M | 0.1% | 2026-Q2 |
| RAYMOND JAMES FINANCIAL INC added | 58,069 | $6M | 0.1% | 2026-Q2 |
| MANUFACTURERS LIFE INSURANCE COMPANY, THE added | 57,170 | $6M | 0.1% | 2026-Q2 |
| Trexquant Investment LP added | 56,248 | $6M | 0.1% | 2026-Q2 |
Ownership over time
Tracked institutional holder count and total shares held by filing quarter (independent scales). The curated-era tail and any mid-ingest latest quarter are handled honestly — a partial quarter is not drawn as a collapse.
Reading this table
Funds hold the same stock for different reasons — an index fund “holds” almost everything, an active manager sizes a name to a mandate and a benchmark, and each fund entered at its own price and time. Because 13F is filed up to 45 days after quarter-end, every row is a backward-looking snapshot; a manager may have traded since. Share-class siblings (a company’s A and C shares) are rolled up to one line so a dual-class name is never double-counted. Compare like-for-like. A large holder is not an endorsement, and a fund exiting is not a warning — this is a starting question, not a verdict.
About 13F filings
A Form 13F is a quarterly disclosure that institutional investment managers with over $100 million in US-listed equities must file with the SEC. In plain English: it is a snapshot of the long stock positions a fund held at the end of a quarter. It covers long US-listed equities only — not short positions, options, cash, or private holdings — and the funds shown are the large sample we track, not the complete 13F universe.