Palo Alto Investors LP holds a focused book of 51 stocks worth $653.9M as of Q1 2026 (disclosed May 15, 2026, a ~45-day 13F lag). This quarter they opened Celldex Therapeutics Inc and trimmed Insmed Inc. Their largest long position is Insmed Inc at 10% of the equity book.
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curl -H "Authorization: Bearer YOUR_API_KEY" \ "https://arkolith.com/api/v1/funds/1306923/holdings"
Use Arkolith to show Palo Alto Investors LP's latest holdings, largest changes, and filing provenance.
Top-heavy: focused book
Share of the disclosed book in its largest positions. A higher top-5 share means a more concentrated, higher-conviction portfolio.
98% mapped to company sectors
Direct operating-company sectors from our SIC-based security master. ETF/fund and unclassified holdings stay visible separately; this is not ETF look-through exposure.
Estimated $ traded · quarter-end prices, no cost basis
Bars show each stock's share of the portfolio. Click a row for its position history.
| # | Security | Value | Shares | % Port | Last move | History |
|---|---|---|---|---|---|---|
| 1 | Insmed Inc COM PAR $.01 | $67.9M | 415.3K | 10.4% | ▼−15% Reduced · −74K sh | |
| 2 | Acadia Pharmaceuticals Inc COM | $63.9M | 2.87M | 9.8% | ▲+16% Added · +389K sh | |
| 3 | PTC Therapeutics Inc COM | $62.8M | 921.6K | 9.6% | ▲+1.9% Added · +18K sh | |
| 4 | Biomarin Pharmaceutical Inc COM | $38.7M | 685.2K | 5.9% | ▼−8.2% Reduced · −61K sh | |
| 5 | United Therapeutics Corp COM | $37.2M | 62.8K | 5.7% | ▲+7.9% Added · +5K sh | |
| 6 | Anaptysbio Inc COM | $35.4M | 638.2K | 5.4% | ▼−7.5% Reduced · −52K sh | |
| 7 | Mirum Pharmaceuticals Inc COM | $30.0M | 325.2K | 4.6% | ▲+108% Added · +169K sh | |
| 8 | Dyne Therapeutics Inc COM | $30.0M | 1.65M | 4.6% | ▲+12% Added · +181K sh | |
| 9 | Biogen Inc COM | $25.8M | 140.7K | 3.9% | ▼−23% Reduced · −43K sh | |
| 10 | Disc Medicine Inc COM | $25.7M | 401.7K | 3.9% | ▲+27% Added · +84K sh | |
| 11 | Iovance Biotherapeutics Inc COM | $22.3M | 6.35M | 3.4% | ▼−11% Reduced · −767K sh | |
| 12 | Syndax Pharmaceuticals Inc COM | $20.2M | 865.0K | 3.1% | ▲+8.9% Added · +70K sh | |
| 13 | Annexon Inc COM | $16.3M | 2.95M | 2.5% | ▲+24% Added · +564K sh | |
| 14 | Amicus Therapeutics Inc COM | $16.1M | 1.11M | 2.5% | ▼−79% Reduced · −4.1M sh | |
| 15 | Novocure Ltd ORD SHS | $14.0M | 1.28M | 2.1% | ▼−1.4% Reduced · −19K sh | |
| 16 | Ultragenyx Pharmaceutical In COM | $12.5M | 596.5K | 1.9% | ▲+29% Added · +135K sh | |
| 17 | Prothena Corp PLC SHS | $11.7M | 1.21M | 1.8% | ▼−8.5% Reduced · −112K sh | |
| 18 | Bicara Therapeutics Inc COM | $10.9M | 550.4K | 1.7% | ▲+84% Added · +252K sh | |
| 19 | Celldex Therapeutics Inc COM NEW | $9.4M | 296.4K | 1.4% | ▲New New position | |
| 20 | Caredx Inc COM | $9.2M | 531.9K | 1.4% | ▲+11% Added · +54K sh | |
| 21 | Alkermes PLC SHS | $8.6M | 242.6K | 1.3% | —Held | |
| 22 | Compass Therapeutics Inc COM | $8.0M | 1.51M | 1.2% | ▼−40% Reduced · −1.0M sh | |
| 23 | Agios Pharmaceuticals Inc COM | $7.2M | 213.6K | 1.1% | ▲+0.5% Added · +1K sh | |
| 24 | Align Technology Inc COM | $7.1M | 41.5K | 1.1% | —Held | |
| 25 | Capricor Therapeutics Inc COM NEW | $7.0M | 229.8K | 1.1% | ▲+1.5% Added · +3K sh | |
| 26 | Travere Therapeutics Inc COM | $6.8M | 230.5K | 1.0% | ▲+108% Added · +120K sh | |
| 27 | Taysha Gene Therapies Inc COM SHS | $6.2M | 1.39M | 1.0% | ▲+18% Added · +208K sh | |
| 28 | Aclaris Therapeutics Inc COM | $6.1M | 1.61M | 0.9% | ▲+3.0% Added · +47K sh | |
| 29 | Denali Therapeutics Inc COM | $4.5M | 234.6K | 0.7% | ▼−63% Reduced · −407K sh | |
| 30 | Xenon Pharmaceuticals Inc COM | $3.0M | 51.3K | 0.5% | ▼−47% Reduced · −45K sh | |
| 31 | Oruka Therapeutics Inc COM | $2.9M | 60.0K | 0.4% | —Held | |
| 32 | Stoke Therapeutics Inc COM | $2.8M | 84.6K | 0.4% | ▲+18% Added · +13K sh | |
| 33 | Edwards Lifesciences Corp COM | $2.7M | 33.6K | 0.4% | —Held | |
| 34 | Neurocrine Biosciences Inc COM | $2.4M | 18.1K | 0.4% | —Held | |
| 35 | Nuvation Bio Inc COM CL A | $2.2M | 508.8K | 0.3% | ▼−5.4% Reduced · −29K sh | |
| 36 | Cytokinetics Inc COM NEW | $2.1M | 32.2K | 0.3% | ▲New New position | |
| 37 | Ehealth Inc COM | $1.9M | 1.48M | 0.3% | ▼−3.2% Reduced · −49K sh | |
| 38 | Crispr Therapeutics AG NAMEN AKT | $1.9M | 39.6K | 0.3% | ▼−3.9% Reduced · −2K sh | |
| 39 | Biontech SE-ADR SPONSORED ADS | $1.7M | 19.6K | 0.3% | —Held | |
| 40 | Pyxis Oncology Inc COMMON STOCK | $1.5M | 1.01M | 0.2% | ▼−2.6% Reduced · −27K sh | |
| 41 | Verastem Inc COM NEW | $1.3M | 246.1K | 0.2% | ▲New New position | |
| 42 | Bicycle Therapeutics PLC-ADR SPONSORED ADS | $937K | 201.9K | 0.1% | ▼−8.7% Reduced · −19K sh | |
| 43 | Madrigal Pharmaceuticals Inc COM | $935K | 1.8K | 0.1% | ▲New New position | |
| 44 | Humana Inc COM | $691K | 4.0K | 0.1% | —Held | |
| 45 | Compass Pathways PLC ADR SPONSORED ADS | $639K | 115.6K | 0.1% | —Held | |
| 46 | Xeris Biopharma Holdings Inc COM | $606K | 104.4K | 0.1% | ▲New New position | |
| 47 | Abeona Therapeutics Inc COM NEW | $488K | 108.9K | 0.1% | —Held | |
| 48 | Inspire Medical Systems Inc COM | $452K | 8.8K | 0.1% | —Held | |
| 49 | Urogen Pharma Ltd COM | $441K | 24.5K | 0.1% | —Held | |
| 50 | Proqr Therapeutics NV SHS EURO | $306K | 188.8K | 0.0% | —Held |
As-of date vs the date the SEC received each filing
Holdings from SEC EDGAR 13F-HR filings, updated quarterly ~45 days after quarter-end. Public domain. The book and weighting are long equity only; disclosed put/call options are listed separately and excluded from those totals. Price-derived performance is withheld until the price-source policy and freshness gate are green.