Palo Alto Investors LP
In its 13F for Q1 2025 (holdings as of March 31, 2025, filed May 15, 2025), Palo Alto Investors LP reported 44 stock positions worth $525.1 million. Its top holding was Insmed (INSM) at 14.3% of the portfolio, followed by Biomarin Pharmaceutical (BMRN, 13.3%) and Amicus Therapeutics (FOLD, 11.4%). Compared with Q4 2024, it opened 3 new positions, sold out of 2, added to 9 and reduced 11. The biggest buy was Anaptysbio (ANAB, shares +21%) and the biggest sale Insmed (INSM, shares −38%).
- Most Recent 13F
- Q2 2026
- Location
- PALO ALTO, CA
- CIK
- 0001306923
- Portfolio Value
- $525.1M (Q1 2025)
- SEC Filing
- 0001306923-25-000014 ↗ filed May 15, 2025
Holdings Value
Holdings 44 stocks · $525.1M
| INSM Insmed Inc. | 14.34% | 987,153 | $75.3M | Reduce -38.4% |
| BMRN Biomarin Pharmaceutical Inc. | 13.34% | 991,207 | $70.1M | Reduce -7.1% |
| FOLD Amicus Therapeutics Inc. | 11.41% | 7,345,002 | $59.9M | Reduce -4.1% |
| ACAD Acadia Pharmaceuticals Inc. | 8.43% | 2,663,925 | $44.2M | Reduce -3.1% |
| UTHR United Therapeutics Corp. | 6.18% | 105,228 | $32.4M | Reduce -32.4% |
| BIIB Biogen Inc. | 5.34% | 204,923 | $28.0M | Add +7.8% |
| ALNY Alnylam Pharmaceuticals Inc. | 4.29% | 83,488 | $22.5M | Reduce -40.6% |
| PTCT PTC Therapeutics Inc. | 3.92% | 404,196 | $20.6M | Add +4.6% |
| PRTA Prothena Corp. PLC | 3.91% | 1,659,734 | $20.5M | Reduce -4.5% |
| ANAB Anaptysbio Inc. | 3.61% | 1,020,713 | $19.0M | Add +20.9% |
| NVCR Novocure Ltd. | 3.40% | 1,002,061 | $17.9M | Add +23.1% |
| SRPT Sarepta Therapeutics Inc. | 2.56% | 210,258 | $13.4M | No change |
| EHTH Ehealth Inc. | 2.14% | 1,684,336 | $11.3M | Reduce -10.3% |
| IOVA Iovance Biotherapeutics Inc. | 2.04% | 3,211,314 | $10.7M | Add +5.6% |
| STAA Staar Surgical Co. | 1.76% | 525,017 | $9.3M | Add +4.8% |
| AGIO Agios Pharmaceuticals Inc. | 1.54% | 276,578 | $8.1M | New |
| ALKS Alkermes PLC | 1.39% | 221,513 | $7.3M | Reduce -23.4% |
| GOSS Gossamer Bio Inc. | 1.31% | 6,276,893 | $6.9M | Reduce 0.0% |
| ALGN Align Technology Inc. | 1.14% | 37,772 | $6.0M | No change |
| SNDX Syndax Pharmaceuticals Inc. | 1.04% | 444,367 | $5.5M | Add +9.7% |
| SLRN Acelyrin Inc. | 0.84% | 1,792,895 | $4.4M | No change |
| DYN Dyne Therapeutics Inc. | 0.66% | 333,391 | $3.5M | New |
| MIRM Mirum Pharmaceuticals Inc. | 0.56% | 64,700 | $2.9M | No change |
| EW Edwards Lifesciences Corp. | 0.54% | 39,473 | $2.9M | No change |
| VERV Verve Therapeutics Inc. | 0.50% | 575,817 | $2.6M | No change |
| BNTX Biontech SE-ADR | 0.44% | 25,206 | $2.3M | No change |
| BCYC Bicycle Therapeutics PLC-ADR | 0.40% | 248,934 | $2.1M | No change |
| TVTX Travere Therapeutics Inc. | 0.38% | 110,719 | $2.0M | No change |
| TSHA Taysha Gene Therapies Inc. | 0.38% | 1,419,468 | $2.0M | Add +75.0% |
| NBIX Neurocrine Biosciences Inc. | 0.28% | 13,334 | $1.5M | New |
| NUVB Nuvation Bio Inc. | 0.26% | 772,652 | $1.4M | No change |
| ALDX Aldeyra Therapeutics Inc. | 0.25% | 225,465 | $1.3M | No change |
| KPTI Karyopharm Therapeutics Inc. | 0.23% | 324,032 | $1.2M | Reduce -93.4% |
| ACRS Aclaris Therapeutics Inc. | 0.23% | 776,028 | $1.2M | Add +36.2% |
| HUM Humana Inc. | 0.20% | 3,985 | $1.1M | No change |
| PYXS Pyxis Oncology Inc. | 0.19% | 1,037,421 | $1.0M | No change |
| STOK Stoke Therapeutics Inc. | 0.16% | 125,861 | $837K | No change |
| VYNE THERAPEUTICS INC | 0.13% | 445,434 | $704K | No change |
| ABEO Abeona Therapeutics Inc. | 0.10% | 108,865 | $518K | No change |
| URGN Urogen Pharma Ltd. | 0.05% | 24,500 | $271K | No change |
| TIL Instil Bio Inc. | 0.04% | 11,165 | $194K | No change |
| AKTX Akari Therapeutics PLC | 0.03% | 146,024 | $181K | No change |
| RLMD Relmada Therapeutics Inc. | 0.03% | 495,146 | $134K | No change |
| GBIO Generation Bio Co. | 0.01% | 150,475 | $61K | No change |
Portfolio Sells Q4 2024 → Q1 2025
| INSM Insmed Inc. | Reduce -38.4% | 14.34% | −2.81 |
| UTHR United Therapeutics Corp. | Reduce -32.4% | 6.18% | −2.34 |
| ALNY Alnylam Pharmaceuticals Inc. | Reduce -40.6% | 4.29% | −0.84 |
| EHTH Ehealth Inc. | Reduce -10.3% | 2.14% | −0.59 |
| NVRO Nevro LLC | Sold out | 0.00% | −0.43 |
| KPTI Karyopharm Therapeutics Inc. | Reduce -93.4% | 0.23% | −0.28 |
| JSPR Jasper Therapeutics Inc. | Sold out | 0.00% | −0.10 |
| ALKS Alkermes PLC | Reduce -23.4% | 1.39% | +0.10 |
| PRTA Prothena Corp. PLC | Reduce -4.5% | 3.91% | +0.18 |
| FOLD Amicus Therapeutics Inc. | Reduce -4.1% | 11.41% | +0.23 |
| GOSS Gossamer Bio Inc. | Reduce 0.0% | 1.31% | +0.43 |
| ACAD Acadia Pharmaceuticals Inc. | Reduce -3.1% | 8.43% | +0.61 |
| BMRN Biomarin Pharmaceutical Inc. | Reduce -7.1% | 13.34% | +2.47 |
Portfolio Buys Q4 2024 → Q1 2025
| ANAB Anaptysbio Inc. | Add +20.9% | 3.61% | +1.88 |
| AGIO Agios Pharmaceuticals Inc. | New | 1.54% | +1.54 |
| PTCT PTC Therapeutics Inc. | Add +4.6% | 3.92% | +1.22 |
| BIIB Biogen Inc. | Add +7.8% | 5.34% | +0.83 |
| DYN Dyne Therapeutics Inc. | New | 0.66% | +0.66 |
| NBIX Neurocrine Biosciences Inc. | New | 0.28% | +0.28 |
| SNDX Syndax Pharmaceuticals Inc. | Add +9.7% | 1.04% | +0.21 |
| TSHA Taysha Gene Therapies Inc. | Add +75.0% | 0.38% | +0.16 |
| ACRS Aclaris Therapeutics Inc. | Add +36.2% | 0.23% | +0.01 |
| STAA Staar Surgical Co. | Add +4.8% | 1.76% | −0.12 |
| NVCR Novocure Ltd. | Add +23.1% | 3.40% | −0.36 |
| IOVA Iovance Biotherapeutics Inc. | Add +5.6% | 2.04% | −1.45 |
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 |