Rock Springs Capital Management LP
In its 13F for Q1 2025 (holdings as of March 31, 2025, filed May 15, 2025), Rock Springs Capital Management LP reported 94 stock positions worth $1.7 billion. Its top holding was Argenx SE - ADR (ARGX) at 6.0% of the portfolio, followed by Eli Lilly (LLY, 5.4%) and Blueprint Medicines (BPMC, 5.1%). Compared with Q4 2024, it opened 6 new positions, sold out of 16, added to 25 and reduced 47. The biggest buy was Merus (MRUS, shares +10%) and the biggest sale Neurocrine Biosciences (NBIX, shares −61%).
- Most Recent 13F
- Q2 2026
- Location
- Baltimore, MD
- CIK
- 0001595725
- Portfolio Value
- $1.7B (Q1 2025)
- SEC Filing
- 0001172661-25-001953 ↗ filed May 15, 2025
Holdings Value
Holdings 94 stocks · $1.7B
| ARGX Argenx SE - ADR | 5.97% | 175,750 | $104.0M | Reduce -23.4% |
| LLY Eli Lilly & Co. | 5.38% | 113,500 | $93.7M | Reduce -21.4% |
| BPMC Blueprint Medicines Corp. | 5.12% | 1,007,569 | $89.2M | Reduce -8.1% |
| MDGL Madrigal Pharmaceuticals Inc. | 3.17% | 166,698 | $55.2M | Reduce -37.1% |
| UNH Unitedhealth Group Inc. | 3.02% | 100,500 | $52.6M | Reduce -42.9% |
| TVTX Travere Therapeutics Inc. | 3.00% | 2,921,196 | $52.3M | Reduce -41.3% |
| ISRG Intuitive Surgical Inc. | 2.90% | 102,000 | $50.5M | Reduce -52.8% |
| RARE Ultragenyx Pharmaceutical Inc. | 2.90% | 1,394,434 | $50.5M | Reduce -19.9% |
| PEN Penumbra Inc. | 2.62% | 171,000 | $45.7M | Reduce -28.8% |
| RVMD Revolution Medicines Inc. | 2.60% | 1,281,640 | $45.3M | Add +5.6% |
| RYTM Rhythm Pharmaceuticals Inc. | 2.54% | 834,188 | $44.2M | Reduce -28.3% |
| MIRM Mirum Pharmaceuticals Inc. | 2.46% | 951,765 | $42.9M | Reduce -35.3% |
| MRUS Merus NV | 2.37% | 980,751 | $41.3M | Add +9.9% |
| INSM Insmed Inc. | 2.26% | 515,900 | $39.4M | Reduce -6.2% |
| ALNY Alnylam Pharmaceuticals Inc. | 2.22% | 143,250 | $38.7M | Reduce -44.1% |
| ASND Ascendis Pharma A/S | 1.93% | 216,000 | $33.7M | Reduce -29.2% |
| ZLAB Zai Lab Ltd.-ADR | 1.88% | 904,592 | $32.7M | Reduce -30.7% |
| XENE Xenon Pharmaceuticals Inc. | 1.79% | 931,681 | $31.3M | Reduce -25.6% |
| NBIX Neurocrine Biosciences Inc. | 1.77% | 279,000 | $30.9M | Reduce -61.3% |
| NUVL Nuvalent Inc. Class A | 1.74% | 427,532 | $30.3M | Reduce -0.6% |
| AGL Agilon Health Inc. | 1.73% | 6,950,000 | $30.1M | Reduce -6.9% |
| PHR Phreesia Inc. | 1.68% | 1,148,336 | $29.4M | Reduce -43.7% |
| BSX Boston Scientific Corp. | 1.60% | 277,000 | $27.9M | Reduce -39.8% |
| AKRO Akero Therapeutics Inc. | 1.56% | 672,759 | $27.2M | Reduce -28.9% |
| DXCM Dexcom Inc. | 1.56% | 397,650 | $27.2M | Add +12.7% |
| IRTC Irhythm Holdings Inc. | 1.53% | 254,300 | $26.6M | Reduce -36.0% |
| EVH Evolent Health Inc. Class A | 1.47% | 2,695,700 | $25.5M | Add +30.9% |
| SRRK Scholar Rock Holding Corp. | 1.41% | 761,541 | $24.5M | Add +6.2% |
| KYMR Kymera Therapeutics Inc. | 1.25% | 794,437 | $21.7M | Reduce -23.2% |
| EXAS Exact Sciences Corp. | 1.19% | 480,000 | $20.8M | Add +6.7% |
| ACHC Acadia Healthcare Co. Inc. | 1.19% | 681,100 | $20.7M | Add +16.7% |
| GPCR Structure Therapeutics Inc. | 1.13% | 1,132,979 | $19.6M | Add +4.8% |
| SMMT Summit Therapeutics Inc. | 1.10% | 995,000 | $19.2M | Reduce -5.6% |
| EW Edwards Lifesciences Corp. | 1.06% | 255,000 | $18.5M | Reduce -53.2% |
| TARS Tarsus Pharmaceuticals Inc. | 1.04% | 354,376 | $18.2M | Add +219.6% |
| THC Tenet Healthcare Corp. | 1.00% | 130,000 | $17.5M | Add +0.6% |
| LEGN Legend Biotech Corp.-ADR | 1.00% | 512,932 | $17.4M | Add +0.2% |
| IMVT Immunovant Inc. | 0.96% | 975,803 | $16.7M | Add +7.3% |
| AZTA Azenta Inc. | 0.94% | 475,000 | $16.5M | No change |
| INSP Inspire Medical Systems Inc. | 0.91% | 99,250 | $15.8M | Reduce -23.6% |
| FOLD Amicus Therapeutics Inc. | 0.89% | 1,909,362 | $15.6M | Reduce -26.6% |
| WRBY Warby Parker Inc. Class A | 0.87% | 835,000 | $15.2M | Reduce -9.2% |
| MREO Mereo Biopharma Group PL-ADR | 0.86% | 6,684,247 | $15.0M | Reduce -30.4% |
| CLDX Celldex Therapeutics Inc. | 0.85% | 812,653 | $14.7M | Reduce -33.5% |
| OSCR Oscar Health Inc. Class A | 0.79% | 1,050,000 | $13.8M | No change |
| WST West Pharmaceutical Services | 0.77% | 60,250 | $13.5M | Reduce -64.3% |
| VERA Vera Therapeutics Inc. | 0.72% | 520,796 | $12.5M | Add +6.8% |
| DHR Danaher Corp. | 0.69% | 58,800 | $12.1M | New |
| NAMS Newamsterdam Pharma Co. NV | 0.63% | 536,111 | $11.0M | Reduce -30.1% |
| SRPT Sarepta Therapeutics Inc. | 0.58% | 159,300 | $10.2M | Reduce -48.2% |
| AGIO Agios Pharmaceuticals Inc. | 0.58% | 342,180 | $10.0M | Reduce -27.4% |
| PHVS Pharvaris NV | 0.56% | 623,402 | $9.8M | Reduce -19.6% |
| CMPX Compass Therapeutics Inc. | 0.54% | 4,962,955 | $9.4M | Reduce -14.1% |
| ELVN Enliven Therapeutics Inc. | 0.53% | 465,871 | $9.2M | Add +8.7% |
| SLNO Soleno Therapeutics Inc. | 0.51% | 124,095 | $8.9M | No change |
| ARDX Ardelyx Inc. | 0.45% | 1,604,975 | $7.9M | Add +9.7% |
| ACRS Aclaris Therapeutics Inc. | 0.44% | 5,046,309 | $7.7M | Reduce -18.7% |
| ZBIO Zenas Biopharma Inc. | 0.40% | 878,667 | $6.9M | No change |
| ETNB 89BIO Inc. | 0.35% | 844,441 | $6.1M | Add +52.8% |
| PRTA Prothena Corp. PLC | 0.35% | 492,601 | $6.1M | Reduce -23.6% |
| JANX Janux Therapeutics Inc. | 0.32% | 204,466 | $5.5M | No change |
| DYN Dyne Therapeutics Inc. | 0.31% | 524,499 | $5.5M | Add +10.5% |
| MLYS Mineralys Therapeutics Inc. | 0.29% | 320,813 | $5.1M | New |
| CGEM Cullinan Therapeutics Inc. | 0.28% | 644,633 | $4.9M | Reduce -13.1% |
| NVRO Nevro LLC filed as NEVRO CORP | 0.27% | 800,494 | $4.7M | Reduce -51.4% |
| BCAX Bicara Therapeutics Inc. | 0.25% | 336,070 | $4.4M | Reduce -24.6% |
| NVAX Novavax Inc. | 0.24% | 650,000 | $4.2M | No change |
| KMTS Kestra Medical Technologies | 0.21% | 145,000 | $3.6M | New |
| GOSS Gossamer Bio Inc. | 0.21% | 3,266,960 | $3.6M | No change |
| LUNG Pulmonx Corp. | 0.19% | 503,700 | $3.4M | Reduce -34.8% |
| INZY Inozyme Pharma Inc. | 0.18% | 3,445,299 | $3.1M | Reduce -10.8% |
| BEAM Beam Therapeutics Inc. | 0.17% | 150,020 | $2.9M | Reduce -40.5% |
| ATEC Alphatec Holdings Inc. | 0.16% | 267,500 | $2.7M | Add +33.8% |
| SGMT Sagimet Biosciences Inc. Class A | 0.15% | 787,808 | $2.6M | No change |
| FOCL Edap TMS SA -ADR | 0.14% | 1,270,000 | $2.5M | Reduce -20.2% |
| JSPR Jasper Therapeutics Inc. | 0.13% | 545,171 | $2.3M | Add +17.7% |
| LENZ Lenz Therapeutics Inc. | 0.12% | 83,082 | $2.1M | Add +183.5% |
| REGN Regeneron Pharmaceuticals | 0.10% | 2,800 | $1.8M | New |
| APLS Apellis Pharmaceuticals Inc. | 0.10% | 80,000 | $1.7M | No change |
| BCRX Biocryst Pharmaceuticals Inc. | 0.10% | 222,011 | $1.7M | Reduce -91.7% |
| MGNX Macrogenics Inc. | 0.08% | 1,145,214 | $1.5M | Add +8.7% |
| CGEN Compugen Ltd. | 0.08% | 989,990 | $1.4M | No change |
| MERSANA THERAPEUTICS INC | 0.08% | 3,814,684 | $1.3M | Add +11.2% |
| NGNE Neurogene Inc. | 0.07% | 104,339 | $1.2M | Add +9.4% |
| AMLX Amylyx Pharmaceuticals Inc. | 0.07% | 343,228 | $1.2M | New |
| SION Sionna Therapeutics Inc. | 0.06% | 99,429 | $1.0M | New |
| APLT Applied Therapeutics Inc. | 0.06% | 2,074,891 | $1.0M | Add +8.2% |
| CATX Perspective Therapeutics Inc. | 0.05% | 444,383 | $947K | No change |
| VIGL Vigil Neuroscience Inc. | 0.05% | 471,958 | $840K | No change |
| PLRX Pliant Therapeutics Inc. | 0.05% | 589,996 | $796K | Add +45.8% |
| SPRB Spruce Biosciences Inc. | 0.04% | 2,609,125 | $757K | No change |
| KRRO Korro Bio Inc. | 0.04% | 35,719 | $622K | No change |
| ADAPY Adaptimmune Therapeutics-ADR | 0.03% | 2,483,468 | $489K | No change |
| TLPH Talphera Inc. | 0.01% | 316,460 | $157K | No change |
Other holdings (2): bonds, preferreds, convertibles and warrants · $5.3M (not counted above)
| Security | Class | Shares / Principal | Value | Change |
|---|---|---|---|---|
| GOSSAMER BIO INC (GOSS 5 06/01/27) | NOTE 5.000% 6/0 · principal | 9,573,000 | $5.3M | No change |
| NUVB.WS Nuvation Bio Inc. -CW27 | *W EXP 02/10/202 | 134,028 | $32K | No change |
Total filed on the 13F, all lines: $1.7B.
Portfolio Sells Q4 2024 → Q1 2025
| NBIX Neurocrine Biosciences Inc. | Reduce -61.3% | 1.77% | −1.98 |
| FRPT Freshpet Inc. | Sold out | 0.00% | −1.85 |
| ISRG Intuitive Surgical Inc. | Reduce -52.8% | 2.90% | −1.40 |
| WST West Pharmaceutical Services | Reduce -64.3% | 0.77% | −1.33 |
| PODD Insulet Corp. | Sold out | 0.00% | −1.14 |
| SRPT Sarepta Therapeutics Inc. | Reduce -48.2% | 0.58% | −0.84 |
| LFST Lifestance Health Group Inc. | Sold out | 0.00% | −0.72 |
| BCRX Biocryst Pharmaceuticals Inc. | Reduce -91.7% | 0.10% | −0.67 |
| CRNX Crinetics Pharmaceuticals Inc. | Sold out | 0.00% | −0.57 |
| EW Edwards Lifesciences Corp. | Reduce -53.2% | 1.06% | −0.48 |
| SWTX Springworks Therapeutics Inc. | Sold out | 0.00% | −0.45 |
| MREO Mereo Biopharma Group PL-ADR | Reduce -30.4% | 0.86% | −0.42 |
| NMRA Neumora Therapeutics Inc. | Sold out | 0.00% | −0.39 |
| UNH Unitedhealth Group Inc. | Reduce -42.9% | 3.02% | −0.38 |
| XNCR Xencor Inc. | Sold out | 0.00% | −0.35 |
| KYMR Kymera Therapeutics Inc. | Reduce -23.2% | 1.25% | −0.34 |
| CLDX Celldex Therapeutics Inc. | Reduce -33.5% | 0.85% | −0.33 |
| TVTX Travere Therapeutics Inc. | Reduce -41.3% | 3.00% | −0.30 |
| PHR Phreesia Inc. | Reduce -43.7% | 1.68% | −0.27 |
| INZY Inozyme Pharma Inc. | Reduce -10.8% | 0.18% | −0.23 |
| BHVN Biohaven Ltd. | Sold out | 0.00% | −0.18 |
| ACRS Aclaris Therapeutics Inc. | Reduce -18.7% | 0.44% | −0.14 |
| CYPH Cypherpunk Technologies Inc. | Sold out | 0.00% | −0.14 |
| NAMS Newamsterdam Pharma Co. NV | Reduce -30.1% | 0.63% | −0.12 |
| ABOS Acumen Pharmaceuticals Inc. | Sold out | 0.00% | −0.12 |
| XLO Xilio Therapeutics Inc. | Sold out | 0.00% | −0.11 |
| AUTL Autolus Therapeutics PLC | Sold out | 0.00% | −0.09 |
| ALNY Alnylam Pharmaceuticals Inc. | Reduce -44.1% | 2.22% | −0.08 |
| XENE Xenon Pharmaceuticals Inc. | Reduce -25.6% | 1.79% | −0.08 |
| BEAM Beam Therapeutics Inc. | Reduce -40.5% | 0.17% | −0.07 |
| CGEM Cullinan Therapeutics Inc. | Reduce -13.1% | 0.28% | −0.06 |
| ALLK Allakos LLC | Sold out | 0.00% | −0.05 |
| BCAX Bicara Therapeutics Inc. | Reduce -24.6% | 0.25% | −0.05 |
| FOLD Amicus Therapeutics Inc. | Reduce -26.6% | 0.89% | −0.04 |
| BMEA Biomea Fusion Inc. | Sold out | 0.00% | −0.03 |
| KYTX Kyverna Therapeutics Inc. | Sold out | 0.00% | −0.03 |
| AGIO Agios Pharmaceuticals Inc. | Reduce -27.4% | 0.58% | −0.02 |
| INSP Inspire Medical Systems Inc. | Reduce -23.6% | 0.91% | −0.01 |
| VINCERX PHARMA INC | Sold out | 0.00% | −0.01 |
| LUNG Pulmonx Corp. | Reduce -34.8% | 0.19% | −0.01 |
| PHVS Pharvaris NV | Reduce -19.6% | 0.56% | −0.01 |
| FOCL Edap TMS SA -ADR | Reduce -20.2% | 0.14% | +0.01 |
| PRTA Prothena Corp. PLC | Reduce -23.6% | 0.35% | +0.01 |
| WRBY Warby Parker Inc. Class A | Reduce -9.2% | 0.87% | +0.02 |
| NVRO Nevro LLC | Reduce -51.4% | 0.27% | +0.03 |
| BSX Boston Scientific Corp. | Reduce -39.8% | 1.60% | +0.04 |
| MDGL Madrigal Pharmaceuticals Inc. | Reduce -37.1% | 3.17% | +0.05 |
| RYTM Rhythm Pharmaceuticals Inc. | Reduce -28.3% | 2.54% | +0.05 |
| RARE Ultragenyx Pharmaceutical Inc. | Reduce -19.9% | 2.90% | +0.11 |
| MIRM Mirum Pharmaceuticals Inc. | Reduce -35.3% | 2.46% | +0.14 |
Portfolio Buys Q4 2024 → Q1 2025
| MRUS Merus NV | Add +9.9% | 2.37% | +0.94 |
| TARS Tarsus Pharmaceuticals Inc. | Add +219.6% | 1.04% | +0.81 |
| DHR Danaher Corp. | New | 0.69% | +0.69 |
| EVH Evolent Health Inc. Class A | Add +30.9% | 1.47% | +0.58 |
| RVMD Revolution Medicines Inc. | Add +5.6% | 2.60% | +0.58 |
| DXCM Dexcom Inc. | Add +12.7% | 1.56% | +0.51 |
| THC Tenet Healthcare Corp. | Add +0.6% | 1.00% | +0.38 |
| LEGN Legend Biotech Corp.-ADR | Add +0.2% | 1.00% | +0.36 |
| ACHC Acadia Healthcare Co. Inc. | Add +16.7% | 1.19% | +0.30 |
| MLYS Mineralys Therapeutics Inc. | New | 0.29% | +0.29 |
| EXAS Exact Sciences Corp. | Add +6.7% | 1.19% | +0.23 |
| SRRK Scholar Rock Holding Corp. | Add +6.2% | 1.41% | +0.22 |
| KMTS Kestra Medical Technologies | New | 0.21% | +0.21 |
| ETNB 89BIO Inc. | Add +52.8% | 0.35% | +0.19 |
| ARDX Ardelyx Inc. | Add +9.7% | 0.45% | +0.17 |
| ELVN Enliven Therapeutics Inc. | Add +8.7% | 0.53% | +0.16 |
| REGN Regeneron Pharmaceuticals | New | 0.10% | +0.10 |
| IMVT Immunovant Inc. | Add +7.3% | 0.96% | +0.10 |
| LENZ Lenz Therapeutics Inc. | Add +183.5% | 0.12% | +0.09 |
| ATEC Alphatec Holdings Inc. | Add +33.8% | 0.16% | +0.09 |
| AMLX Amylyx Pharmaceuticals Inc. | New | 0.07% | +0.07 |
| SION Sionna Therapeutics Inc. | New | 0.06% | +0.06 |
| GPCR Structure Therapeutics Inc. | Add +4.8% | 1.13% | +0.01 |
| APLT Applied Therapeutics Inc. | Add +8.2% | 0.06% | −0.00 |
| NGNE Neurogene Inc. | Add +9.4% | 0.07% | −0.01 |
| MGNX Macrogenics Inc. | Add +8.7% | 0.08% | −0.05 |
| VERA Vera Therapeutics Inc. | Add +6.8% | 0.72% | −0.07 |
| DYN Dyne Therapeutics Inc. | Add +10.5% | 0.31% | −0.11 |
| MERSANA THERAPEUTICS INC | Add +11.2% | 0.08% | −0.11 |
| PLRX Pliant Therapeutics Inc. | Add +45.8% | 0.05% | −0.16 |
| JSPR Jasper Therapeutics Inc. | Add +17.7% | 0.13% | −0.24 |
Notes & Other Activity Q4 2024 → Q1 2025
| NEVRO CORP (NVRO 2.75 04/01/25) | NOTE 2.750% 4/0 · principal | Sold out | 500,000 | $489Kbefore exit |
Bonds, preferreds, convertibles and warrants; not part of the stock holdings or percentages above.
All Filings
| Quarter | Positions | 13F Reported Value | Top Holdings |
|---|---|---|---|
| Q2 2026 | 104 | $2.0B | RVMD, TVTX, LLY, MDGL, MIRM |
| Q1 2026 | 100 | $1.7B | RVMD, LLY, MDGL, MIRM, ARGX |
| Q4 2025 | 96 | $1.9B | LLY, RVMD, ARGX, TVTX, MDGL |
| Q3 2025 | 90 | $1.7B | ARGX, LLY, RYTM, MDGL, RVMD |
| Q2 2025 | 91 | $1.6B | ARGX, LLY, MRUS, RYTM, INSM |
| Q1 2025 | 94 | $1.7B | ARGX, LLY, BPMC, MDGL, UNH |
| Q4 2024 | 104 | $2.6B | ARGX, ISRG, LLY, NBIX, BPMC |
| Q3 2024 | 106 | $3.1B | UNH, ISRG, ARGX, LLY, RARE |
| Q2 2024 | 106 | $3.3B | BPMC, UNH, ISRG, NBIX, LLY |
| Q1 2024 | 108 | $3.9B | BPMC, IMCR, NBIX, EVH, ISRG |