# Palo Alto Investors LP 13F holdings

> Latest reported SEC 13F equity book. Teaser: top 10 of 51 long-equity positions.
> CIK 1306923. Latest filing Q1 2026, as of quarter end 2026-03-31. Long-equity book $653.9M.

## Top holdings (teaser)

| # | Ticker | Issuer | Value | % of book | Change |
|---|--------|--------|-------|-----------|--------|
| 1 | n/a | Insmed Inc | $67.9M | 10.4% | Reduced |
| 2 | n/a | Acadia Pharmaceuticals Inc | $63.9M | 9.8% | Added |
| 3 | n/a | PTC Therapeutics Inc | $62.8M | 9.6% | Added |
| 4 | n/a | Biomarin Pharmaceutical Inc | $38.7M | 5.9% | Reduced |
| 5 | n/a | United Therapeutics Corp | $37.2M | 5.7% | Added |
| 6 | n/a | Anaptysbio Inc | $35.4M | 5.4% | Reduced |
| 7 | n/a | Mirum Pharmaceuticals Inc | $30.0M | 4.6% | Added |
| 8 | n/a | Dyne Therapeutics Inc | $30.0M | 4.6% | Added |
| 9 | n/a | Biogen Inc | $25.8M | 3.9% | Reduced |
| 10 | n/a | Disc Medicine Inc | $25.7M | 3.9% | Added |

## Latest moves

Bought: Celldex Therapeutics Inc, Cytokinetics Inc, Verastem Inc
Sold: Insmed Inc, Biomarin Pharmaceutical Inc, Anaptysbio Inc

Counts and totals reflect the 13F filers and securities Arkolith tracks, not the entire institutional universe. Option legs are excluded from the book above.

## Full data via the API and MCP

This page is a teaser. The complete book, full quarter-over-quarter history, and per-datapoint
provenance are available through the metered REST API and MCP server.

- Endpoint: https://arkolith.com/api/mcp (transport: streamable-http)
- Auth: Bearer API key. Mint one and copy a ready-to-paste command at https://arkolith.com/connect
- Claude Code: `claude mcp add --transport http arkolith https://arkolith.com/api/mcp --header "Authorization: Bearer YOUR_API_KEY"`
- Discovery: `tools/list` is free; `tools/call` is metered by credits.

### Machine-readable
- Tool catalog JSON: https://arkolith.com/api/mcp/catalog
- MCP descriptor: https://arkolith.com/.well-known/mcp.json
- OpenAPI 3.1 REST spec: https://arkolith.com/openapi.json
- Full LLM guide: https://arkolith.com/llms-full.txt
- Human docs: https://arkolith.com/docs

## Source and method

- Source: SEC EDGAR 13F-HR (public domain). Long-equity positions only (option legs excluded). Filed quarterly, about a 45-day lag.
- Primary source: https://www.sec.gov/Archives/edgar/data/1306923/000130692326000004/xslForm13F_X02/primary_doc.xml
- Human page: https://arkolith.com/fund/palo-alto-investors-lp-1306923
- Per-datapoint lineage: call the `provenance.get` MCP tool for the source URL and fetch history behind any figure.

Paid product with a one-time evaluation grant at signup (no card to evaluate). Most calls cost 1 credit (~$0.01); heavier point-in-time / cross-source tools cost more.

_Latest disclosed public filings. Data, not investment advice._