Company · Ownership research

RHYTHM PHARMACEUTICALS, INC. RYTM

CIK 0001649904 · CUSIP 76243J105

Insider trading Initial holdings Institutional holders

Quarter-end disclosures, not live holdings.

Several CUSIPs are reported for this company; this page shows CUSIP 76243J105 (RYTM), not CUSIP 76243J955 (RYTM), CUSIP 76243J905 (RYTM), and does not merge CUSIPs.

This page lists the top 20 of 286 rows by value; the complete set is available through the API.

Some filings reported values in thousands; those figures were scaled ×1,000 to dollars.

Top 20 institutions

Weight means this stock's share of the manager's own portfolio.

By reported value

#	Manager	Value	Manager weight	Change vs prior	Source
01	RA CAPITAL MANAGEMENT, L.P. CIK 1346824 · View history	$579.81M 6,666,837 shares	6.14%	0(0.00%)Unchanged	SEC filing ↗ May 15, 2026	▾
02	BlackRock, Inc. CIK 2012383 · View history	$542.45M 6,237,151 shares	0.01%	-60.18K(-1.00%)Reduced	SEC filing ↗ May 13, 2026	▾
03	BAKER BROS. ADVISORS LP CIK 1263508 · View history	$487.42M 5,604,483 shares	2.80%	0(0.00%)Unchanged	SEC filing ↗ May 15, 2026	▾
04	PRIMECAP MANAGEMENT CO/CA/ CIK 763212 · View history	$297.22M 3,417,509 shares	0.23%	-61.16K(-1.80%)Reduced	SEC filing ↗ May 11, 2026	▾
05	VANGUARD PORTFOLIO MANAGEMENT LLC CIK 2100121 · Amended · View history	$264.45M 3,040,718 shares	0.01%	—	SEC filing ↗ May 8, 2026	▾
06	VANGUARD CAPITAL MANAGEMENT LLC CIK 2100119 · Amended · View history	$258.11M 2,967,825 shares	0.01%	—	SEC filing ↗ May 15, 2026	▾
07	PERCEPTIVE ADVISORS LLC CIK 1224962 · Amended · View history	$206.45M 2,373,795 shares	4.08%	-172.60K(-6.80%)Reduced	SEC filing ↗ May 29, 2026	▾
08	STATE STREET CORP CIK 93751 · View history	$197.58M 2,271,851 shares	0.01%	+73.24K(+3.30%)Added	SEC filing ↗ May 15, 2026	▾
09	GOLDMAN SACHS GROUP INC CIK 886982 · View history	$170.93M 1,965,432 shares	0.02%	+134.57K(+7.30%)Added	SEC filing ↗ May 15, 2026	▾
10	WESTFIELD CAPITAL MANAGEMENT CO LP CIK 1177719 · View history	$167.78M 1,929,123 shares	0.70%	+661.97K(+52.20%)Added	SEC filing ↗ May 11, 2026	▾
11	FMR LLC CIK 315066 · View history	$146.95M 1,689,671 shares	0.01%	-16.65K(-1.00%)Reduced	SEC filing ↗ May 15, 2026	▾
12	PRICE T ROWE ASSOCIATES INC /MD/ CIK 80255 · View history	$143.93M 1,654,876 shares	0.02%	+94.03K(+6.00%)Added	SEC filing ↗ May 15, 2026	▾
13	Polar Capital Holdings Plc CIK 1837309 · View history	$140.51M 1,615,586 shares	0.61%	+430.19K(+36.30%)Added	SEC filing ↗ May 15, 2026	▾
14	CITADEL ADVISORS LLC CIK 1423053 · View history	$123.38M 1,418,619 shares	0.09%	+1.27M(+825.30%)Added	SEC filing ↗ May 15, 2026	▾
15	GEODE CAPITAL MANAGEMENT, LLC CIK 1214717 · View history	$123.20M 1,416,269 shares	0.01%	+40.54K(+2.90%)Added	SEC filing ↗ May 15, 2026	▾
16	JPMORGAN CHASE & CO CIK 19617 · Amended · View history	$120.02M 1,553,644 shares	0.01%	+129.66K(+9.10%)Added	SEC filing ↗ May 13, 2026	▾
17	FEDERATED HERMES, INC. CIK 1056288 · View history	$111.87M 1,286,303 shares	0.18%	-337.54K(-20.80%)Reduced	SEC filing ↗ May 11, 2026	▾
18	Checkpoint Capital L.P. CIK 1977548 · View history	$106.73M 1,227,200 shares	38.30%	+235.00K(+23.70%)Added	SEC filing ↗ May 15, 2026	▾
19	ALLIANCEBERNSTEIN L.P. CIK 1109448 · View history	$97.45M 910,413 shares	0.03%	-19.82K(-2.10%)Reduced	SEC filing ↗ May 15, 2026	▾
20	Capital Research Global Investors CIK 1422848 · View history	$97.01M 1,115,460 shares	0.02%	+130.37K(+13.20%)Added	SEC filing ↗ May 13, 2026	▾

Showing 20 / 286 institutions. The complete set is available through the API.

Coverage & totals by quarter

Reporting institutions

286

Cancelled or null records excluded

Disclosed shares

73,573,451

Not deduplicated across managers

Disclosed value

$6.42B

Not market cap or free float

Reporting institutions by quarter

Counts also change with data coverage and reporting entities; they do not measure net buying. Distinct managers with a live stock row in this CUSIP; totals may include overlapping filings and are not a share of the company.

RHYTHM PHARMACEUTICALS, INC. · Q1 2026

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Sources, coverage & how to read this data

Figures are as reported to the SEC and merged with later amendments where Akkru could match them. Preview limits apply to what is listed, not to the totals, which come from the complete reported data. Nothing is zero-filled: a missing quarter or month is shown as missing.