Rock Springs Capital Management LP's Q2 2026 13F: 16 new positions, 12 exits
Form 13F-HR for the quarter ended Jun 30, 2026 · filed Aug 14, 2026 · 104 reported positions · accession 0001172661-26-003527
What changed this quarter
| Activity | Security | Weight before | Weight now | Change | Shares | Shares % |
|---|---|---|---|---|---|---|
| Reduced | ARGENX SE (ARGX) | 4.2% | 2.4% | −1.9 pts | −45,750 sh | −46% |
| Increased | TRAVERE THERAPEUTICS INC (TVTX) | 2.6% | 6.0% | +3.5 pts | +701K sh | +47% |
| Exited | ARCELLX INC (ACLX) | 1.1% | — | −1.1 pts | −170K sh | −100% |
| New | AVALYN PHARMACEUTICALS INC (AVLN) | — | 1.1% | +1.1 pts | +663K sh | new |
| New | HEMAB THERAPEUTICS HLDGS INC (COAG) | — | 1.0% | +1.0 pts | +575K sh | new |
| Reduced | REVOLUTION MEDICINES INC (RVMD) | 6.9% | 10.1% | +3.2 pts | −104K sh | −9% |
| Reduced | ENLIVEN THERAPEUTICS INC (ELVN) | 1.9% | 1.2% | −0.8 pts | −362K sh | −44% |
| Exited | CENTESSA PHARMACEUTICALS PLC (CNTA) | 0.8% | — | −0.8 pts | −352K sh | −100% |
| New | PARABILIS MEDICINES INC (PBLS) | — | 0.8% | +0.8 pts | +578K sh | new |
| Increased | CYTOKINETICS INC (CYTK) | 0.2% | 0.8% | +0.6 pts | +143K sh | +314% |
| Exited | SOLENO THERAPEUTICS INC (SLNO) | 0.5% | — | −0.5 pts | −257K sh | −100% |
| Reduced | AGIOS PHARMACEUTICALS INC (AGIO) | 1.6% | 1.0% | −0.6 pts | −267K sh | −33% |
| Exited | REGENERON PHARMACEUTICALS (REGN) | 0.5% | — | −0.5 pts | −10,100 sh | −100% |
| Reduced | ULTRAGENYX PHARMACEUTICAL IN (RARE) | 1.5% | 1.6% | +0.1 pts | −251K sh | −21% |
| Exited | APELLIS PHARMACEUTICALS INC (APLS) | 0.4% | — | −0.4 pts | −163K sh | −100% |
| Exited | TERNS PHARMACEUTICALS INC (TERN) | 0.4% | — | −0.4 pts | −114K sh | −100% |
| Increased | MINIMED GROUP INC (MMED) | 0.9% | 1.1% | +0.2 pts | +465K sh | +44% |
| New | OMEROS CORP (OMER) | — | 0.3% | +0.3 pts | +718K sh | new |
| New | DEFINIUM THERAPEUTICS INC (DFTX) | — | 0.3% | +0.3 pts | +143K sh | new |
| New | MOBIA MED INC (MOBI) | — | 0.3% | +0.3 pts | +418K sh | new |
| Increased | ERASCA INC (ERAS) | 1.1% | 1.3% | +0.2 pts | +299K sh | +27% |
| Increased | INSMED INC (INSM) | 3.0% | 1.9% | −1.1 pts | +47,850 sh | +15% |
| Reduced | KYMERA THERAPEUTICS INC (KYMR) | 2.4% | 2.5% | +0.1 pts | −43,715 sh | −9% |
| Increased | INSPIRE MED SYS INC (INSP) | 0.4% | 0.5% | +0.1 pts | +112K sh | +85% |
| New | TREVI THERAPEUTICS INC (TRVI) | — | 0.2% | +0.2 pts | +260K sh | new |
| Reduced | XENON PHARMACEUTICALS INC (XENE) | 2.6% | 2.0% | −0.6 pts | −79,113 sh | −10% |
| Exited | SPDR SERIES TRUST (XBI) | 0.2% | — | −0.2 pts | −30,000 sh | −100% |
| Increased | STRYKER CORPORATION (SYK) | 0.3% | 0.4% | +0.2 pts | +14,200 sh | +96% |
| Increased | UNITEDHEALTH GROUP INC (UNH) | 0.8% | 1.3% | +0.4 pts | +10,750 sh | +20% |
| Reduced | AZENTA INC (AZTA) | 0.7% | 0.5% | −0.2 pts | −166K sh | −29% |
| Reduced | COGENT BIOSCIENCES INC (COGT) | 1.4% | 1.0% | −0.4 pts | −108K sh | −17% |
| New | SPYRE THERAPEUTICS INC (SYRE) | — | 0.2% | +0.2 pts | +42,254 sh | new |
| Reduced | OMADA HEALTH INC (OMDA) | 0.4% | 0.4% | 0.0 pts | −168K sh | −31% |
| Increased | TARSUS PHARMACEUTICALS INC (TARS) | 0.9% | 0.9% | −0.1 pts | +51,908 sh | +23% |
| Reduced | VERA THERAPEUTICS INC (VERA) | 1.2% | 0.9% | −0.3 pts | −76,001 sh | −15% |
| Increased | DANAHER CORP DEL (DHR) | 0.7% | 0.7% | 0.0 pts | +14,800 sh | +24% |
| Exited | EDWARDS LIFESCIENCES CORP (EW) | 0.1% | — | −0.1 pts | −28,900 sh | −100% |
| Reduced | VIKING THERAPEUTICS INC (VKTX) | 0.2% | 0.0% | −0.1 pts | −70,500 sh | −73% |
| New | NERVGEN PHARMA CORP (NGENF) | — | 0.1% | +0.1 pts | +1.21M sh | new |
| New | MEDTRONIC PLC (MDT) | — | 0.1% | +0.1 pts | +30,900 sh | new |
| Reduced | INTUITIVE SURGICAL INC (ISRG) | 2.2% | 1.5% | −0.7 pts | −5,540 sh | −7% |
| Reduced | ALNYLAM PHARMACEUTICALS INC (ALNY) | 1.4% | 1.0% | −0.5 pts | −7,250 sh | −10% |
| Increased | TANGO THERAPEUTICS INC (TNGX) | 0.5% | 0.7% | +0.2 pts | +69,636 sh | +18% |
| Increased | MADRIGAL PHARMACEUTICALS INC (MDGL) | 5.3% | 4.6% | −0.7 pts | +4,000 sh | +2% |
| Exited | ACADIA HEALTHCARE COMPANY IN (ACHC) | 0.1% | — | −0.1 pts | −75,500 sh | −100% |
| Reduced | SURGERY PARTNERS INC (SGRY) | 0.1% | 0.1% | −0.1 pts | −124K sh | −60% |
| New | SAGIMET BIOSCIENCES INC (SGMT) | — | 0.1% | +0.1 pts | +250K sh | new |
| Increased | CORCEPT THERAPEUTICS INC (CORT) | 0.1% | 0.3% | +0.2 pts | +21,750 sh | +43% |
| Increased | INDIVIOR PHARMACEUTICALS INC (INDVZZZZ) | 0.4% | 0.5% | +0.1 pts | +45,500 sh | +23% |
| Increased | CELLDEX THERAPEUTICS INC NEW (CLDX) | 1.2% | 1.3% | +0.1 pts | +48,876 sh | +8% |
The 50 largest of 98 changes, by size of the trade. Full holdings for this quarter.
Reported by the fund in its Form 13F filed with the SEC; holdings are as of the quarter-end report date and may have changed since. For informational purposes only — not investment advice or a recommendation to buy or sell any security. FilingExplorer is not affiliated with or endorsed by this fund. How this brief is compiled
† Security identifier (CUSIP) changed — read as one continuing position, not an exit and a new position:
- ASCENDIS PHARMA A/S (ASND): 04351P101 → K08588103, 194K → 169K shares (share count changed with the identifier; not shown as a trade)
Top 10 positions — 44.0% of the equity book
Changes in the top 10 this quarter: KYMR entered · INSM left
| # | Security | Weight before | Weight now | |
|---|---|---|---|---|
| 1 | REVOLUTION MEDICINES INC (RVMD) | 6.9% | 10.1% | |
| 2 | TRAVERE THERAPEUTICS INC (TVTX) | 2.6% | 6.0% | |
| 3 | ELI LILLY & CO (LLY) | 5.4% | 5.8% | |
| 4 | MADRIGAL PHARMACEUTICALS INC (MDGL) | 5.3% | 4.6% | |
| 5 | MIRUM PHARMACEUTICALS INC (MIRM) | 4.4% | 4.6% | |
| 6 | RHYTHM PHARMACEUTICALS INC (RYTM) | 3.5% | 3.8% | |
| 7 | KYMERA THERAPEUTICS INC (KYMR) | 2.4% | 2.5% | Entered the top 10 |
| 8 | ARGENX SE (ARGX) | 4.2% | 2.4% | |
| 9 | ASCENDIS PHARMA A/S (ASND) | 2.6% | 2.2% | |
| 10 | XENON PHARMACEUTICALS INC (XENE) | 2.6% | 2.0% | |
| — | INSMED INC (INSM) | 3.0% | 1.9% | Left the top 10 |
Weights are each position's reported value as a share of the fund's reported equity positions (options and principal-amount holdings excluded).