Rock Springs Capital Management LP
Position in RARE — Ultragenyx Pharmaceutical Inc.
CIK 1595725
Baltimore, MD
Position in RARE
as of Mar 31, 2026
· filed May 15, 2026
Position Value
$25,533,294
-$3,613,249 QoQ
Shares Held
1,218,773
-3.8% QoQ
Ownership
1.24%
of shares outstanding
% of Portfolio
1.51%
of 13F equity value
Holder Rank
—
not a current holder
Holding Since
Mar 2020
25 quarters on record
Voting authority
Sole 100.ToString("F0")%
Shared 0.ToString("F0")%
None 0.ToString("F0")%
Common Shares in RARE Over Time
Shares Held
Position Value (USD)
Position in Biotechnology
Healthcare · as of Mar 31, 2026Rock Springs Capital Management LP holds $1,246,050,197 across 66 Biotechnology names. RARE ranks #15 (2.0% of the industry book) .
| # | Ticker | Company | Shares | Value (USD) | Open |
|---|---|---|---|---|---|
| 1 | RVMD |
Revolution Medicines, Inc.
|
1,209,465 | $117,620,471 | |
| 2 | MDGL |
Madrigal Pharmaceuticals, Inc.
|
170,999 | $89,512,846 | |
| 3 | MIRM |
Mirum Pharmaceuticals, Inc.
|
811,294 | $74,947,339 | |
| 4 | ARGX |
Argenx SE
|
98,500 | $71,929,625 | |
| 5 | RYTM |
Rhythm Pharmaceuticals, Inc.
|
689,748 | $59,987,383 | |
| 6 | INSM |
INSMED Inc
|
314,300 | $51,394,336 | |
| 7 | ASND |
Ascendis Pharma A/S
|
194,000 | $44,373,620 | |
| 8 | XENE |
Xenon Pharmaceuticals Inc.
|
763,020 | $44,369,613 |
All Filings in RARE
Export CSV
25 filing rows on record
| Report Date | Value (USD) | Shares | Type | Discretion | Filed | |
|---|---|---|---|---|---|---|
| 2026-03-31 | $25,533,294 | 1,218,773 | Shares | Sole | 2026-05-15 | |
| 2025-12-31 | $29,146,543 | 1,267,241 | Shares | Sole | 2026-02-17 | |
| 2025-09-30 | $37,489,937 | 1,246,341 | Shares | Sole | 2025-11-14 | |
| 2025-06-30 | $50,579,377 | 1,391,072 | Shares | Sole | 2025-08-14 | |
| 2025-03-31 | $50,492,455 | 1,394,434 | Shares | Sole | 2025-05-15 | |
| 2024-12-31 | $73,193,932 | 1,739,813 | Shares | Sole | 2025-02-14 | |
| 2024-09-30 | $109,893,009 | 1,978,272 | Shares | Sole | 2024-11-14 | |
| 2024-06-30 | $79,079,359 | 1,924,072 | Shares | Sole | 2024-08-14 | |
| 2024-03-31 | $82,871,855 | 1,774,938 | Shares | Sole | 2024-05-15 | |
| 2023-12-31 | $83,878,097 | 1,754,038 | Shares | Sole | 2024-02-14 | |
| 2023-09-30 | $52,635,121 | 1,476,441 | Shares | Sole | 2023-11-14 | |
| 2023-06-30 | $63,856,328 | 1,384,269 | Shares | Sole | 2023-08-14 | |
| 2023-03-31 | $53,589,680 | 1,336,401 | Shares | Sole | 2023-05-15 | |
| 2022-12-31 | $59,778,626 | 1,290,279 | Shares | Sole | 2023-02-14 | |
| 2022-09-30 | $49,194,748 | 1,187,992 | Shares | Sole | 2022-11-14 | |
| 2022-06-30 | $65,210,169 | 1,093,030 | Shares | Sole | 2022-08-15 | |
| 2022-03-31 | $74,661,275 | 1,028,109 | Shares | Sole | 2022-05-16 | |
| 2021-12-31 | $74,328,916 | 883,921 | Shares | Sole | 2022-02-14 | |
| 2021-09-30 | $72,252,020 | 801,109 | Shares | Sole | 2021-11-15 | |
| 2021-06-30 | $44,337,750 | 465,000 | Shares | Sole | 2021-08-16 | |
| 2021-03-31 | $51,237,000 | 450,000 | Shares | Sole | 2021-05-17 | |
| 2020-12-31 | $78,420,595 | 566,500 | Shares | Sole | 2021-02-16 | |
| 2020-09-30 | $47,410,561 | 576,841 | Shares | Sole | 2020-11-16 | |
| 2020-06-30 | $50,595,903 | 646,841 | Shares | Sole | 2020-08-14 | |
| 2020-03-31 | $33,224,754 | 747,800 | Shares | Sole | 2020-05-15 | |
| No filing history on record for this holder in this stock. | ||||||