WESTFIELD CAPITAL MANAGEMENT CO LP
Position in RYTM — Rhythm Pharmaceuticals, Inc.
CIK 1177719
BOSTON, MA
Position in RYTM
as of Mar 31, 2026
· filed May 11, 2026
Position Value
$167,775,827
+$32,139,235 QoQ
Shares Held
1,929,123
+52.2% QoQ
Ownership
2.81%
of shares outstanding
% of Portfolio
0.70%
of 13F equity value
Holder Rank
—
not a current holder
Holding Since
Mar 2025
5 quarters on record
Voting authority
Sole 92.04685237799767.ToString("F0")%
Shared 0.ToString("F0")%
None 7.953147622002329.ToString("F0")%
Common Shares in RYTM Over Time
Shares Held
Position Value (USD)
Position in Biotechnology
Healthcare · as of Mar 31, 2026WESTFIELD CAPITAL MANAGEMENT CO LP holds $2,468,245,086 across 19 Biotechnology names. RYTM ranks #4 (6.8% of the industry book) .
| # | Ticker | Company | Shares | Value (USD) | Open |
|---|---|---|---|---|---|
| 1 | ASND |
Ascendis Pharma A/S
|
4,813,440 | $1,100,978,131 | |
| 2 | INSM |
INSMED Inc
|
1,468,459 | $240,122,415 | |
| 3 | PCVX |
Vaxcyte, Inc.
|
3,646,138 | $211,877,079 | |
| 4 | RYTM |
Rhythm Pharmaceuticals, Inc.
This page
|
1,929,123 | $167,775,827 | |
| 5 | RVMD |
Revolution Medicines, Inc.
|
1,556,578 | $151,377,210 | |
| 6 | ABVX |
Abivax S.A.
|
1,322,938 | $147,309,146 | |
| 7 | LEGN |
Legend Biotech Corp
|
5,763,475 | $104,261,262 | |
| 8 | XENE |
Xenon Pharmaceuticals Inc.
|
1,401,483 | $81,496,236 |
All Filings in RYTM
Export CSV
5 filing rows on record
| Report Date | Value (USD) | Shares | Type | Discretion | Filed | |
|---|---|---|---|---|---|---|
| 2026-03-31 | $167,775,827 | 1,929,123 | Shares | Sole | 2026-05-11 | |
| 2025-12-31 | $135,636,592 | 1,267,158 | Shares | Sole | 2026-02-11 | |
| 2025-09-30 | $107,958,713 | 1,069,004 | Shares | Sole | 2025-11-12 | |
| 2025-06-30 | $102,966,082 | 1,629,468 | Shares | Sole | 2025-08-12 | |
| 2025-03-31 | $71,037,643 | 1,341,092 | Shares | Sole | 2025-05-09 | |
| No filing history on record for this holder in this stock. | ||||||