Palo Alto Investors LP
In its 13F for Q3 2025 (holdings as of September 30, 2025, filed November 14, 2025), Palo Alto Investors LP reported 44 stock positions worth $540.4 million. Its top holding was Insmed (INSM) at 13.1% of the portfolio, followed by PTC Therapeutics (PTCT, 9.8%) and Acadia Pharmaceuticals (ACAD, 9.7%). Compared with Q2 2025, it opened 3 new positions, sold out of 4, added to 13 and reduced 19. The biggest buy was PTC Therapeutics (PTCT, shares +112%) and the biggest sale Insmed (INSM, shares −43%).
- Most Recent 13F
- Q2 2026
- Location
- PALO ALTO, CA
- CIK
- 0001306923
- Portfolio Value
- $540.4M (Q3 2025)
- SEC Filing
- 0001306923-25-000019 ↗ filed Nov 14, 2025
Holdings Value
Holdings 44 stocks · $540.4M
| INSM Insmed Inc. | 13.11% | 491,805 | $70.8M | Reduce -43.1% |
| PTCT PTC Therapeutics Inc. | 9.80% | 862,613 | $52.9M | Add +112.2% |
| ACAD Acadia Pharmaceuticals Inc. | 9.74% | 2,466,684 | $52.6M | Reduce -3.8% |
| FOLD Amicus Therapeutics Inc. | 7.83% | 5,367,798 | $42.3M | Reduce -4.3% |
| BMRN Biomarin Pharmaceutical Inc. | 7.56% | 754,007 | $40.8M | Reduce -10.3% |
| BIIB Biogen Inc. | 4.81% | 185,661 | $26.0M | Reduce -9.8% |
| UTHR United Therapeutics Corp. | 4.51% | 58,186 | $24.4M | Reduce -39.1% |
| ANAB Anaptysbio Inc. | 3.82% | 673,520 | $20.6M | Reduce -17.1% |
| IOVA Iovance Biotherapeutics Inc. | 3.06% | 7,618,132 | $16.5M | Add +122.2% |
| NVCR Novocure Ltd. | 3.00% | 1,256,159 | $16.2M | Add +30.5% |
| DYN Dyne Therapeutics Inc. | 2.96% | 1,262,674 | $16.0M | Add +376.5% |
| IRON Disc Medicine Inc. | 2.74% | 224,300 | $14.8M | Add +54.0% |
| ALNY Alnylam Pharmaceuticals Inc. | 2.73% | 32,320 | $14.7M | Reduce -57.2% |
| GOSS Gossamer Bio Inc. | 2.66% | 5,464,349 | $14.4M | Reduce -4.8% |
| PRTA Prothena Corp. PLC | 2.39% | 1,324,028 | $12.9M | Add +3.9% |
| RARE Ultragenyx Pharmaceutical Inc. | 2.06% | 369,531 | $11.1M | Add +658.0% |
| AGIO Agios Pharmaceuticals Inc. | 1.97% | 265,497 | $10.7M | Reduce -1.2% |
| SNDX Syndax Pharmaceuticals Inc. | 1.86% | 654,930 | $10.1M | Add +47.4% |
| EHTH Ehealth Inc. | 1.23% | 1,544,619 | $6.7M | Reduce -2.1% |
| DNLI Denali Therapeutics Inc. | 1.10% | 408,006 | $5.9M | Add +70.1% |
| ALGN Align Technology Inc. | 1.06% | 45,735 | $5.7M | Add +21.1% |
| ALKS Alkermes PLC | 1.02% | 183,938 | $5.5M | Reduce -16.8% |
| RNAM Avidity Biosciences Inc. | 0.89% | 109,831 | $4.8M | Reduce -7.6% |
| MIRM Mirum Pharmaceuticals Inc. | 0.88% | 64,700 | $4.7M | No change |
| CDNA Caredx Inc. | 0.85% | 316,204 | $4.6M | New |
| TSHA Taysha Gene Therapies Inc. | 0.75% | 1,246,033 | $4.1M | No change |
| NUVB Nuvation Bio Inc. | 0.70% | 1,020,547 | $3.8M | Add +32.1% |
| ACRS Aclaris Therapeutics Inc. | 0.55% | 1,566,840 | $3.0M | Add +12.7% |
| CRSP Crispr Therapeutics AG | 0.49% | 41,226 | $2.7M | Reduce -7.6% |
| TVTX Travere Therapeutics Inc. | 0.49% | 110,719 | $2.6M | No change |
| EW Edwards Lifesciences Corp. | 0.48% | 33,640 | $2.6M | Reduce -14.8% |
| NBIX Neurocrine Biosciences Inc. | 0.47% | 18,117 | $2.5M | Add +35.9% |
| STOK Stoke Therapeutics Inc. | 0.46% | 105,427 | $2.5M | Reduce -16.2% |
| PYXS Pyxis Oncology Inc. | 0.43% | 1,037,421 | $2.3M | No change |
| BNTX Biontech SE-ADR | 0.36% | 19,614 | $1.9M | Reduce -22.2% |
| BCYC Bicycle Therapeutics PLC-ADR | 0.32% | 221,071 | $1.7M | Reduce -11.2% |
| ALDX Aldeyra Therapeutics Inc. | 0.22% | 225,465 | $1.2M | No change |
| HUM Humana Inc. | 0.19% | 3,985 | $1.0M | No change |
| ORKA Oruka Therapeutics Inc. | 0.15% | 59,985 | $791K | New |
| ABEO Abeona Therapeutics Inc. | 0.11% | 108,865 | $575K | No change |
| URGN Urogen Pharma Ltd. | 0.09% | 24,500 | $489K | No change |
| PRQR Proqr Therapeutics NV | 0.07% | 188,807 | $402K | New |
| AKTX Akari Therapeutics PLC | 0.03% | 146,024 | $147K | No change |
| GBIO Generation Bio Co. | 0.02% | 15,047 | $92K | Reduce -90.0% |
Portfolio Sells Q2 2025 → Q3 2025
| INSM Insmed Inc. | Reduce -43.1% | 13.11% | −5.42 |
| STAA Staar Surgical Co. | Sold out | 0.00% | −2.83 |
| ALNY Alnylam Pharmaceuticals Inc. | Reduce -57.2% | 2.73% | −2.51 |
| BMRN Biomarin Pharmaceutical Inc. | Reduce -10.3% | 7.56% | −2.27 |
| ACAD Acadia Pharmaceuticals Inc. | Reduce -3.8% | 9.74% | −2.02 |
| UTHR United Therapeutics Corp. | Reduce -39.1% | 4.51% | −1.32 |
| BIIB Biogen Inc. | Reduce -9.8% | 4.81% | −0.69 |
| ALKS Alkermes PLC | Reduce -16.8% | 1.02% | −0.32 |
| EHTH Ehealth Inc. | Reduce -2.1% | 1.23% | −0.23 |
| BNTX Biontech SE-ADR | Reduce -22.2% | 0.36% | −0.21 |
| EW Edwards Lifesciences Corp. | Reduce -14.8% | 0.48% | −0.17 |
| KPTI Karyopharm Therapeutics Inc. | Sold out | 0.00% | −0.17 |
| VYNE THERAPEUTICS INC | Sold out | 0.00% | −0.16 |
| ALMS Alumis Inc. | Sold out | 0.00% | −0.09 |
| BCYC Bicycle Therapeutics PLC-ADR | Reduce -11.2% | 0.32% | −0.05 |
| ANAB Anaptysbio Inc. | Reduce -17.1% | 3.82% | −0.02 |
| GBIO Generation Bio Co. | Reduce -90.0% | 0.02% | +0.01 |
| CRSP Crispr Therapeutics AG | Reduce -7.6% | 0.49% | +0.03 |
| AGIO Agios Pharmaceuticals Inc. | Reduce -1.2% | 1.97% | +0.07 |
| STOK Stoke Therapeutics Inc. | Reduce -16.2% | 0.46% | +0.15 |
| RNAM Avidity Biosciences Inc. | Reduce -7.6% | 0.89% | +0.17 |
| FOLD Amicus Therapeutics Inc. | Reduce -4.3% | 7.83% | +0.99 |
| GOSS Gossamer Bio Inc. | Reduce -4.8% | 2.66% | +1.16 |
Portfolio Buys Q2 2025 → Q3 2025
| PTCT PTC Therapeutics Inc. | Add +112.2% | 9.80% | +5.57 |
| DYN Dyne Therapeutics Inc. | Add +376.5% | 2.96% | +2.42 |
| IOVA Iovance Biotherapeutics Inc. | Add +122.2% | 3.06% | +1.80 |
| RARE Ultragenyx Pharmaceutical Inc. | Add +658.0% | 2.06% | +1.68 |
| IRON Disc Medicine Inc. | Add +54.0% | 2.74% | +1.10 |
| SNDX Syndax Pharmaceuticals Inc. | Add +47.4% | 1.86% | +0.98 |
| CDNA Caredx Inc. | New | 0.85% | +0.85 |
| PRTA Prothena Corp. PLC | Add +3.9% | 2.39% | +0.74 |
| DNLI Denali Therapeutics Inc. | Add +70.1% | 1.10% | +0.38 |
| NUVB Nuvation Bio Inc. | Add +32.1% | 0.70% | +0.38 |
| ORKA Oruka Therapeutics Inc. | New | 0.15% | +0.15 |
| ACRS Aclaris Therapeutics Inc. | Add +12.7% | 0.55% | +0.13 |
| NBIX Neurocrine Biosciences Inc. | Add +35.9% | 0.47% | +0.11 |
| PRQR Proqr Therapeutics NV | New | 0.07% | +0.07 |
| ALGN Align Technology Inc. | Add +21.1% | 1.06% | −0.46 |
| NVCR Novocure Ltd. | Add +30.5% | 3.00% | −0.64 |
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 |