Palo Alto Investors LP
In its 13F for Q4 2025 (holdings as of December 31, 2025, filed February 17, 2026), Palo Alto Investors LP reported 49 stock positions worth $718.4 million. Its top holding was Insmed (INSM) at 11.9% of the portfolio, followed by Amicus Therapeutics (FOLD, 10.3%) and PTC Therapeutics (PTCT, 9.6%). Compared with Q3 2025, it opened 8 new positions, sold out of 3, added to 12 and reduced 13. The biggest buy was a new position in Compass Therapeutics (CMPX) and the biggest sale an exit from Alnylam Pharmaceuticals (ALNY).
- Most Recent 13F
- Q2 2026
- Location
- PALO ALTO, CA
- CIK
- 0001306923
- Portfolio Value
- $718.4M (Q4 2025)
- SEC Filing
- 0001306923-26-000002 ↗ filed Feb 17, 2026
Holdings Value
Holdings 49 stocks · $718.4M
| INSM Insmed Inc. | 11.86% | 489,482 | $85.2M | Reduce -0.5% |
| FOLD Amicus Therapeutics Inc. | 10.32% | 5,205,767 | $74.1M | Reduce -3.0% |
| PTCT PTC Therapeutics Inc. | 9.56% | 903,916 | $68.7M | Add +4.8% |
| ACAD Acadia Pharmaceuticals Inc. | 9.24% | 2,484,031 | $66.3M | Add +0.7% |
| BMRN Biomarin Pharmaceutical Inc. | 6.17% | 746,256 | $44.3M | Reduce -1.0% |
| ANAB Anaptysbio Inc. | 4.66% | 690,032 | $33.5M | Add +2.5% |
| BIIB Biogen Inc. | 4.50% | 183,571 | $32.3M | Reduce -1.1% |
| DYN Dyne Therapeutics Inc. | 4.01% | 1,472,197 | $28.8M | Add +16.6% |
| UTHR United Therapeutics Corp. | 3.95% | 58,186 | $28.4M | No change |
| IRON Disc Medicine Inc. | 3.51% | 317,456 | $25.2M | Add +41.5% |
| IOVA Iovance Biotherapeutics Inc. | 2.70% | 7,116,676 | $19.4M | Reduce -6.6% |
| NVCR Novocure Ltd. | 2.34% | 1,298,964 | $16.8M | Add +3.4% |
| SNDX Syndax Pharmaceuticals Inc. | 2.32% | 794,507 | $16.7M | Add +21.3% |
| GOSS Gossamer Bio Inc. | 1.93% | 4,471,592 | $13.9M | Reduce -18.2% |
| CMPX Compass Therapeutics Inc. | 1.89% | 2,532,419 | $13.6M | New |
| PRTA Prothena Corp. PLC | 1.76% | 1,320,510 | $12.6M | Reduce -0.3% |
| MIRM Mirum Pharmaceuticals Inc. | 1.72% | 156,421 | $12.4M | Add +141.8% |
| ANNX Annexon Inc. | 1.67% | 2,384,192 | $12.0M | New |
| RARE Ultragenyx Pharmaceutical Inc. | 1.48% | 461,294 | $10.6M | Add +24.8% |
| DNLI Denali Therapeutics Inc. | 1.47% | 641,239 | $10.6M | Add +57.2% |
| CDNA Caredx Inc. | 1.25% | 478,220 | $9.0M | Add +51.2% |
| EHTH Ehealth Inc. | 0.98% | 1,531,429 | $7.0M | Reduce -0.8% |
| ALKS Alkermes PLC | 0.94% | 242,560 | $6.8M | Add +31.9% |
| CAPR Capricor Therapeutics Inc. | 0.91% | 226,304 | $6.5M | New |
| TSHA Taysha Gene Therapies Inc. | 0.91% | 1,183,195 | $6.5M | Reduce -5.0% |
| ALGN Align Technology Inc. | 0.90% | 41,520 | $6.5M | Reduce -9.2% |
| AGIO Agios Pharmaceuticals Inc. | 0.81% | 212,499 | $5.8M | Reduce -20.0% |
| BCAX Bicara Therapeutics Inc. | 0.70% | 298,575 | $5.0M | New |
| NUVB Nuvation Bio Inc. | 0.67% | 538,079 | $4.8M | Reduce -47.3% |
| ACRS Aclaris Therapeutics Inc. | 0.66% | 1,566,840 | $4.7M | No change |
| XENE Xenon Pharmaceuticals Inc. | 0.60% | 96,519 | $4.3M | New |
| TVTX Travere Therapeutics Inc. | 0.59% | 110,719 | $4.2M | No change |
| EW Edwards Lifesciences Corp. | 0.40% | 33,640 | $2.9M | No change |
| NBIX Neurocrine Biosciences Inc. | 0.36% | 18,117 | $2.6M | No change |
| STOK Stoke Therapeutics Inc. | 0.32% | 72,022 | $2.3M | Reduce -31.7% |
| CRSP Crispr Therapeutics AG | 0.30% | 41,226 | $2.2M | No change |
| BNTX Biontech SE-ADR | 0.26% | 19,614 | $1.9M | No change |
| ORKA Oruka Therapeutics Inc. | 0.25% | 59,985 | $1.8M | No change |
| BCYC Bicycle Therapeutics PLC-ADR | 0.22% | 221,071 | $1.6M | No change |
| PYXS Pyxis Oncology Inc. | 0.17% | 1,037,421 | $1.2M | No change |
| ALDX Aldeyra Therapeutics Inc. | 0.16% | 225,465 | $1.2M | No change |
| HUM Humana Inc. | 0.14% | 3,985 | $1.0M | No change |
| INSP Inspire Medical Systems Inc. | 0.11% | 8,772 | $809K | New |
| CMPS Compass Pathways PLC | 0.11% | 115,616 | $798K | New |
| URGN Urogen Pharma Ltd. | 0.08% | 24,500 | $574K | No change |
| ABEO Abeona Therapeutics Inc. | 0.08% | 108,865 | $574K | No change |
| PRQR Proqr Therapeutics NV | 0.05% | 188,807 | $381K | No change |
| GBIO Generation Bio Co. | 0.01% | 15,047 | $85K | New |
| AKTX Akari Therapeutics PLC | 0.01% | 146,024 | $42K | No change |
Portfolio Sells Q3 2025 → Q4 2025
| ALNY Alnylam Pharmaceuticals Inc. | Sold out | 0.00% | −2.73 |
| BMRN Biomarin Pharmaceutical Inc. | Reduce -1.0% | 6.17% | −1.38 |
| INSM Insmed Inc. | Reduce -0.5% | 11.86% | −1.25 |
| AGIO Agios Pharmaceuticals Inc. | Reduce -20.0% | 0.81% | −1.17 |
| RNAM Avidity Biosciences Inc. | Sold out | 0.00% | −0.89 |
| GOSS Gossamer Bio Inc. | Reduce -18.2% | 1.93% | −0.73 |
| PRTA Prothena Corp. PLC | Reduce -0.3% | 1.76% | −0.64 |
| IOVA Iovance Biotherapeutics Inc. | Reduce -6.6% | 2.70% | −0.35 |
| BIIB Biogen Inc. | Reduce -1.1% | 4.50% | −0.32 |
| EHTH Ehealth Inc. | Reduce -0.8% | 0.98% | −0.25 |
| ALGN Align Technology Inc. | Reduce -9.2% | 0.90% | −0.16 |
| STOK Stoke Therapeutics Inc. | Reduce -31.7% | 0.32% | −0.14 |
| NUVB Nuvation Bio Inc. | Reduce -47.3% | 0.67% | −0.03 |
| GBIO Generation Bio Co. | Sold out | 0.00% | −0.02 |
| TSHA Taysha Gene Therapies Inc. | Reduce -5.0% | 0.91% | +0.15 |
| FOLD Amicus Therapeutics Inc. | Reduce -3.0% | 10.32% | +2.49 |
Portfolio Buys Q3 2025 → Q4 2025
| CMPX Compass Therapeutics Inc. | New | 1.89% | +1.89 |
| ANNX Annexon Inc. | New | 1.67% | +1.67 |
| DYN Dyne Therapeutics Inc. | Add +16.6% | 4.01% | +1.05 |
| CAPR Capricor Therapeutics Inc. | New | 0.91% | +0.91 |
| MIRM Mirum Pharmaceuticals Inc. | Add +141.8% | 1.72% | +0.84 |
| ANAB Anaptysbio Inc. | Add +2.5% | 4.66% | +0.84 |
| IRON Disc Medicine Inc. | Add +41.5% | 3.51% | +0.77 |
| BCAX Bicara Therapeutics Inc. | New | 0.70% | +0.70 |
| XENE Xenon Pharmaceuticals Inc. | New | 0.60% | +0.60 |
| SNDX Syndax Pharmaceuticals Inc. | Add +21.3% | 2.32% | +0.46 |
| CDNA Caredx Inc. | Add +51.2% | 1.25% | +0.40 |
| DNLI Denali Therapeutics Inc. | Add +57.2% | 1.47% | +0.38 |
| INSP Inspire Medical Systems Inc. | New | 0.11% | +0.11 |
| CMPS Compass Pathways PLC | New | 0.11% | +0.11 |
| GBIO Generation Bio Co. | New | 0.01% | +0.01 |
| ALKS Alkermes PLC | Add +31.9% | 0.94% | −0.08 |
| PTCT PTC Therapeutics Inc. | Add +4.8% | 9.56% | −0.24 |
| ACAD Acadia Pharmaceuticals Inc. | Add +0.7% | 9.24% | −0.50 |
| RARE Ultragenyx Pharmaceutical Inc. | Add +24.8% | 1.48% | −0.58 |
| NVCR Novocure Ltd. | Add +3.4% | 2.34% | −0.67 |
All Filings
| Quarter | Positions | 13F Reported Value | Top Holdings |
|---|---|---|---|
| Q2 2026Amended | 52 | $723.7M | PTCT, ACAD, INSM, MIRM, ANAB |
| Q1 2026 | 51 | $653.9M | INSM, ACAD, PTCT, BMRN, UTHR |
| Q4 2025 | 49 | $718.4M | INSM, FOLD, PTCT, ACAD, BMRN |
| Q3 2025 | 44 | $540.4M | INSM, PTCT, ACAD, FOLD, BMRN |
| Q2 2025 | 45 | $470.0M | INSM, ACAD, BMRN, FOLD, UTHR |
| Q1 2025 | 44 | $525.1M | INSM, BMRN, FOLD, ACAD, UTHR |
| Q4 2024 | 43 | $645.4M | INSM, FOLD, BMRN, UTHR, ACAD |
| Q3 2024 | 45 | $769.9M | INSM, FOLD, BMRN, UTHR, BIIB |
| Q2 2024 | 39 | $863.0M | INSM, BMRN, FOLD, UTHR, BIIB |
| Q1 2024 | 38 | $886.7M | INSM, FOLD, BMRN, BIIB, UTHR |