Rock Springs Capital Management LP
In its 13F for Q2 2025 (holdings as of June 30, 2025, filed August 14, 2025), Rock Springs Capital Management LP reported 91 stock positions worth $1.6 billion. Its top holding was Argenx SE - ADR (ARGX) at 6.1% of the portfolio, followed by Eli Lilly (LLY, 5.7%) and Merus (MRUS, 3.5%). Compared with Q1 2025, it opened 9 new positions, sold out of 12, added to 32 and reduced 29. The biggest buy was Agios Pharmaceuticals (AGIO, shares +189%) and the biggest sale Blueprint Medicines (BPMC, shares −82%).
- Most Recent 13F
- Q2 2026
- Location
- Baltimore, MD
- CIK
- 0001595725
- Portfolio Value
- $1.6B (Q2 2025)
- SEC Filing
- 0001172661-25-003273 ↗ filed Aug 14, 2025
Holdings Value
Holdings 91 stocks · $1.6B
| ARGX Argenx SE - ADR | 6.06% | 175,750 | $96.9M | No change |
| LLY Eli Lilly & Co. | 5.68% | 116,500 | $90.8M | Add +2.6% |
| MRUS Merus NV | 3.50% | 1,063,608 | $55.9M | Add +8.4% |
| RYTM Rhythm Pharmaceuticals Inc. | 3.40% | 861,153 | $54.4M | Add +3.2% |
| INSM Insmed Inc. | 3.30% | 525,000 | $52.8M | Add +1.8% |
| RARE Ultragenyx Pharmaceutical Inc. | 3.16% | 1,391,072 | $50.6M | Reduce -0.2% |
| RVMD Revolution Medicines Inc. | 3.06% | 1,330,960 | $49.0M | Add +3.9% |
| ISRG Intuitive Surgical Inc. | 2.79% | 82,000 | $44.6M | Reduce -19.6% |
| MDGL Madrigal Pharmaceuticals Inc. | 2.65% | 140,296 | $42.5M | Reduce -15.8% |
| MIRM Mirum Pharmaceuticals Inc. | 2.60% | 818,206 | $41.6M | Reduce -14.0% |
| BSX Boston Scientific Corp. | 2.38% | 355,000 | $38.1M | Add +28.2% |
| ASND Ascendis Pharma A/S | 2.34% | 217,000 | $37.5M | Add +0.5% |
| IRTC Irhythm Holdings Inc. | 2.33% | 242,500 | $37.3M | Reduce -4.6% |
| AKRO Akero Therapeutics Inc. | 2.14% | 640,526 | $34.2M | Reduce -4.8% |
| PEN Penumbra Inc. | 2.06% | 128,500 | $33.0M | Reduce -24.9% |
| AGIO Agios Pharmaceuticals Inc. | 2.06% | 989,745 | $32.9M | Add +189.3% |
| ALNY Alnylam Pharmaceuticals Inc. | 2.04% | 100,000 | $32.6M | Reduce -30.2% |
| EVH Evolent Health Inc. Class A | 1.99% | 2,820,700 | $31.8M | Add +4.6% |
| ZLAB Zai Lab Ltd.-ADR | 1.90% | 871,392 | $30.5M | Reduce -3.7% |
| EXAS Exact Sciences Corp. | 1.90% | 572,000 | $30.4M | Add +19.2% |
| XENE Xenon Pharmaceuticals Inc. | 1.82% | 931,681 | $29.2M | No change |
| TVTX Travere Therapeutics Inc. | 1.77% | 1,908,208 | $28.2M | Reduce -34.7% |
| SRRK Scholar Rock Holding Corp. | 1.76% | 794,133 | $28.1M | Add +4.3% |
| DXCM Dexcom Inc. | 1.56% | 286,750 | $25.0M | Reduce -27.9% |
| PHR Phreesia Inc. | 1.49% | 837,300 | $23.8M | Reduce -27.1% |
| BPMC Blueprint Medicines Corp. | 1.49% | 185,500 | $23.8M | Reduce -81.6% |
| GPCR Structure Therapeutics Inc. | 1.47% | 1,135,879 | $23.6M | Add +0.3% |
| THC Tenet Healthcare Corp. | 1.43% | 130,000 | $22.9M | No change |
| CAI Caris Life Sciences Inc. | 1.33% | 793,651 | $21.2M | New |
| KYMR Kymera Therapeutics Inc. | 1.23% | 450,374 | $19.7M | Reduce -43.3% |
| OMDA Omada Health Inc. | 1.05% | 919,951 | $16.8M | New |
| CLDX Celldex Therapeutics Inc. | 1.03% | 812,653 | $16.5M | No change |
| AZTA Azenta Inc. | 1.02% | 530,400 | $16.3M | Add +11.7% |
| ACHC Acadia Healthcare Co. Inc. | 0.99% | 696,000 | $15.8M | Add +2.2% |
| UNH Unitedhealth Group Inc. | 0.98% | 50,500 | $15.8M | Reduce -49.8% |
| TARS Tarsus Pharmaceuticals Inc. | 0.95% | 373,750 | $15.1M | Add +5.5% |
| SMMT Summit Therapeutics Inc. | 0.94% | 710,000 | $15.1M | Reduce -28.6% |
| AGL Agilon Health Inc. | 0.94% | 6,550,400 | $15.1M | Reduce -5.8% |
| OSCR Oscar Health Inc. Class A | 0.94% | 700,000 | $15.0M | Reduce -33.3% |
| VERA Vera Therapeutics Inc. | 0.91% | 617,396 | $14.5M | Add +18.6% |
| ELVN Enliven Therapeutics Inc. | 0.88% | 701,408 | $14.1M | Add +50.6% |
| INSP Inspire Medical Systems Inc. | 0.87% | 107,500 | $14.0M | Add +8.3% |
| SLNO Soleno Therapeutics Inc. | 0.81% | 154,528 | $12.9M | Add +24.5% |
| CMPX Compass Therapeutics Inc. | 0.81% | 4,962,955 | $12.9M | No change |
| XBI SS SPDR S&P Biotech ETF | 0.79% | 151,750 | $12.6M | New |
| ACLX Arcellx Inc. | 0.77% | 186,314 | $12.3M | New |
| MREO Mereo Biopharma Group PL-ADR | 0.76% | 4,465,292 | $12.1M | Reduce -33.2% |
| DHR Danaher Corp. | 0.73% | 59,000 | $11.7M | Add +0.3% |
| FOLD Amicus Therapeutics Inc. | 0.70% | 1,960,334 | $11.2M | Add +2.7% |
| WST West Pharmaceutical Services | 0.70% | 51,030 | $11.2M | Reduce -15.3% |
| NBIX Neurocrine Biosciences Inc. | 0.70% | 88,800 | $11.2M | Reduce -68.2% |
| PHVS Pharvaris NV | 0.69% | 623,402 | $11.0M | No change |
| EW Edwards Lifesciences Corp. | 0.64% | 131,000 | $10.2M | Reduce -48.6% |
| NAMS Newamsterdam Pharma Co. NV | 0.61% | 536,111 | $9.7M | No change |
| ARDX Ardelyx Inc. | 0.56% | 2,286,273 | $9.0M | Add +42.5% |
| NUVL Nuvalent Inc. Class A | 0.45% | 93,328 | $7.1M | Reduce -78.2% |
| ACRS Aclaris Therapeutics Inc. | 0.42% | 4,769,309 | $6.8M | Reduce -5.5% |
| CDTX Cidara Therapeutics Inc. | 0.41% | 134,133 | $6.5M | New |
| ZBIO Zenas Biopharma Inc. | 0.39% | 640,467 | $6.2M | Reduce -27.1% |
| REGN Regeneron Pharmaceuticals | 0.37% | 11,300 | $5.9M | Add +303.6% |
| COGT Cogent Biosciences Inc. | 0.36% | 800,199 | $5.7M | New |
| DYN Dyne Therapeutics Inc. | 0.35% | 580,998 | $5.5M | Add +10.8% |
| CGEM Cullinan Therapeutics Inc. | 0.31% | 668,233 | $5.0M | Add +3.7% |
| JANX Janux Therapeutics Inc. | 0.30% | 210,266 | $4.9M | Add +2.8% |
| MLYS Mineralys Therapeutics Inc. | 0.27% | 324,513 | $4.4M | Add +1.1% |
| TMO Thermo Fisher Scientific Inc. | 0.25% | 10,000 | $4.1M | New |
| GOSS Gossamer Bio Inc. | 0.25% | 3,266,960 | $4.0M | No change |
| IMVT Immunovant Inc. | 0.22% | 221,500 | $3.5M | Reduce -77.3% |
| AMLX Amylyx Pharmaceuticals Inc. | 0.20% | 499,764 | $3.2M | Add +45.6% |
| BCAX Bicara Therapeutics Inc. | 0.20% | 336,070 | $3.1M | No change |
| JSPR Jasper Therapeutics Inc. | 0.19% | 545,171 | $3.0M | No change |
| PRTA Prothena Corp. PLC | 0.19% | 492,601 | $3.0M | No change |
| ATEC Alphatec Holdings Inc. | 0.19% | 267,500 | $3.0M | No change |
| LENZ Lenz Therapeutics Inc. | 0.15% | 83,982 | $2.5M | Add +1.1% |
| FOCL Edap TMS SA -ADR | 0.13% | 1,270,000 | $2.1M | No change |
| CGEN Compugen Ltd. | 0.11% | 989,990 | $1.8M | No change |
| SION Sionna Therapeutics Inc. | 0.11% | 99,429 | $1.7M | No change |
| LUNG Pulmonx Corp. | 0.11% | 651,100 | $1.7M | Add +29.3% |
| NGNE Neurogene Inc. | 0.10% | 104,339 | $1.6M | No change |
| CATX Perspective Therapeutics Inc. | 0.10% | 444,383 | $1.5M | No change |
| APLS Apellis Pharmaceuticals Inc. | 0.09% | 84,300 | $1.5M | Add +5.4% |
| SRPT Sarepta Therapeutics Inc. | 0.07% | 68,600 | $1.2M | Reduce -56.9% |
| MERSANA THERAPEUTICS INC | 0.07% | 3,814,684 | $1.1M | No change |
| APLT Applied Therapeutics Inc. | 0.04% | 2,075,991 | $646K | Add +0.1% |
| ADAPY Adaptimmune Therapeutics-ADR | 0.04% | 2,483,468 | $595K | No change |
| KRRO Korro Bio Inc. | 0.03% | 35,719 | $446K | No change |
| CRL Charles River Laboratories | 0.03% | 2,700 | $410K | New |
| ETNB 89BIO Inc. | 0.02% | 40,000 | $393K | Reduce -95.3% |
| PCVX Vaxcyte Inc. | 0.02% | 11,100 | $361K | New |
| NVAX Novavax Inc. | 0.02% | 53,900 | $340K | Reduce -91.7% |
| TLPH Talphera Inc. | 0.01% | 316,460 | $146K | No change |
Other holdings (2): bonds, preferreds, convertibles and warrants · $5.0M (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 | $5.0M | No change |
| NUVB.WS Nuvation Bio Inc. -CW27 | *W EXP 02/10/202 | 134,028 | $36K | No change |
Total filed on the 13F, all lines: $1.6B.
Portfolio Sells Q1 2025 → Q2 2025
| BPMC Blueprint Medicines Corp. | Reduce -81.6% | 1.49% | −3.63 |
| UNH Unitedhealth Group Inc. | Reduce -49.8% | 0.98% | −2.04 |
| NUVL Nuvalent Inc. Class A | Reduce -78.2% | 0.45% | −1.29 |
| TVTX Travere Therapeutics Inc. | Reduce -34.7% | 1.77% | −1.24 |
| NBIX Neurocrine Biosciences Inc. | Reduce -68.2% | 0.70% | −1.07 |
| LEGN Legend Biotech Corp.-ADR | Sold out | 0.00% | −1.00 |
| WRBY Warby Parker Inc. Class A | Sold out | 0.00% | −0.87 |
| AGL Agilon Health Inc. | Reduce -5.8% | 0.94% | −0.79 |
| IMVT Immunovant Inc. | Reduce -77.3% | 0.22% | −0.74 |
| PEN Penumbra Inc. | Reduce -24.9% | 2.06% | −0.56 |
| MDGL Madrigal Pharmaceuticals Inc. | Reduce -15.8% | 2.65% | −0.51 |
| SRPT Sarepta Therapeutics Inc. | Reduce -56.9% | 0.07% | −0.51 |
| EW Edwards Lifesciences Corp. | Reduce -48.6% | 0.64% | −0.42 |
| ETNB 89BIO Inc. | Reduce -95.3% | 0.02% | −0.33 |
| NVRO Nevro LLC | Sold out | 0.00% | −0.27 |
| NVAX Novavax Inc. | Reduce -91.7% | 0.02% | −0.22 |
| KMTS Kestra Medical Technologies | Sold out | 0.00% | −0.21 |
| PHR Phreesia Inc. | Reduce -27.1% | 1.49% | −0.19 |
| ALNY Alnylam Pharmaceuticals Inc. | Reduce -30.2% | 2.04% | −0.18 |
| INZY Inozyme Pharma Inc. | Sold out | 0.00% | −0.18 |
| BEAM Beam Therapeutics Inc. | Sold out | 0.00% | −0.17 |
| SMMT Summit Therapeutics Inc. | Reduce -28.6% | 0.94% | −0.16 |
| SGMT Sagimet Biosciences Inc. Class A | Sold out | 0.00% | −0.15 |
| ISRG Intuitive Surgical Inc. | Reduce -19.6% | 2.79% | −0.11 |
| MREO Mereo Biopharma Group PL-ADR | Reduce -33.2% | 0.76% | −0.11 |
| BCRX Biocryst Pharmaceuticals Inc. | Sold out | 0.00% | −0.10 |
| MGNX Macrogenics Inc. | Sold out | 0.00% | −0.08 |
| WST West Pharmaceutical Services | Reduce -15.3% | 0.70% | −0.08 |
| VIGL Vigil Neuroscience Inc. | Sold out | 0.00% | −0.05 |
| PLRX Pliant Therapeutics Inc. | Sold out | 0.00% | −0.05 |
| SPRB Spruce Biosciences Inc. | Sold out | 0.00% | −0.04 |
| ACRS Aclaris Therapeutics Inc. | Reduce -5.5% | 0.42% | −0.02 |
| KYMR Kymera Therapeutics Inc. | Reduce -43.3% | 1.23% | −0.02 |
| ZBIO Zenas Biopharma Inc. | Reduce -27.1% | 0.39% | −0.01 |
| DXCM Dexcom Inc. | Reduce -27.9% | 1.56% | +0.01 |
| ZLAB Zai Lab Ltd.-ADR | Reduce -3.7% | 1.90% | +0.03 |
| MIRM Mirum Pharmaceuticals Inc. | Reduce -14.0% | 2.60% | +0.14 |
| OSCR Oscar Health Inc. Class A | Reduce -33.3% | 0.94% | +0.15 |
| RARE Ultragenyx Pharmaceutical Inc. | Reduce -0.2% | 3.16% | +0.26 |
| AKRO Akero Therapeutics Inc. | Reduce -4.8% | 2.14% | +0.57 |
| IRTC Irhythm Holdings Inc. | Reduce -4.6% | 2.33% | +0.81 |
Portfolio Buys Q1 2025 → Q2 2025
| AGIO Agios Pharmaceuticals Inc. | Add +189.3% | 2.06% | +1.48 |
| CAI Caris Life Sciences Inc. | New | 1.33% | +1.33 |
| MRUS Merus NV | Add +8.4% | 3.50% | +1.13 |
| OMDA Omada Health Inc. | New | 1.05% | +1.05 |
| INSM Insmed Inc. | Add +1.8% | 3.30% | +1.04 |
| RYTM Rhythm Pharmaceuticals Inc. | Add +3.2% | 3.40% | +0.87 |
| XBI SS SPDR S&P Biotech ETF | New | 0.79% | +0.79 |
| BSX Boston Scientific Corp. | Add +28.2% | 2.38% | +0.78 |
| ACLX Arcellx Inc. | New | 0.77% | +0.77 |
| EXAS Exact Sciences Corp. | Add +19.2% | 1.90% | +0.71 |
| EVH Evolent Health Inc. Class A | Add +4.6% | 1.99% | +0.52 |
| RVMD Revolution Medicines Inc. | Add +3.9% | 3.06% | +0.46 |
| ASND Ascendis Pharma A/S | Add +0.5% | 2.34% | +0.41 |
| CDTX Cidara Therapeutics Inc. | New | 0.41% | +0.41 |
| COGT Cogent Biosciences Inc. | New | 0.36% | +0.36 |
| ELVN Enliven Therapeutics Inc. | Add +50.6% | 0.88% | +0.35 |
| SRRK Scholar Rock Holding Corp. | Add +4.3% | 1.76% | +0.35 |
| GPCR Structure Therapeutics Inc. | Add +0.3% | 1.47% | +0.35 |
| SLNO Soleno Therapeutics Inc. | Add +24.5% | 0.81% | +0.30 |
| LLY Eli Lilly & Co. | Add +2.6% | 5.68% | +0.30 |
| REGN Regeneron Pharmaceuticals | Add +303.6% | 0.37% | +0.27 |
| TMO Thermo Fisher Scientific Inc. | New | 0.25% | +0.25 |
| VERA Vera Therapeutics Inc. | Add +18.6% | 0.91% | +0.19 |
| AMLX Amylyx Pharmaceuticals Inc. | Add +45.6% | 0.20% | +0.13 |
| ARDX Ardelyx Inc. | Add +42.5% | 0.56% | +0.11 |
| AZTA Azenta Inc. | Add +11.7% | 1.02% | +0.08 |
| DHR Danaher Corp. | Add +0.3% | 0.73% | +0.04 |
| CGEM Cullinan Therapeutics Inc. | Add +3.7% | 0.31% | +0.03 |
| LENZ Lenz Therapeutics Inc. | Add +1.1% | 0.15% | +0.03 |
| DYN Dyne Therapeutics Inc. | Add +10.8% | 0.35% | +0.03 |
| CRL Charles River Laboratories | New | 0.03% | +0.03 |
| PCVX Vaxcyte Inc. | New | 0.02% | +0.02 |
| APLS Apellis Pharmaceuticals Inc. | Add +5.4% | 0.09% | −0.01 |
| JANX Janux Therapeutics Inc. | Add +2.8% | 0.30% | −0.01 |
| APLT Applied Therapeutics Inc. | Add +0.1% | 0.04% | −0.02 |
| MLYS Mineralys Therapeutics Inc. | Add +1.1% | 0.27% | −0.02 |
| INSP Inspire Medical Systems Inc. | Add +8.3% | 0.87% | −0.04 |
| LUNG Pulmonx Corp. | Add +29.3% | 0.11% | −0.09 |
| TARS Tarsus Pharmaceuticals Inc. | Add +5.5% | 0.95% | −0.10 |
| FOLD Amicus Therapeutics Inc. | Add +2.7% | 0.70% | −0.19 |
| ACHC Acadia Healthcare Co. Inc. | Add +2.2% | 0.99% | −0.20 |
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 |