# Mitsui Sumitomo Insurance Co Ltd 13F holdings

> Latest reported SEC 13F equity book. Teaser: top 1 of 1 long-equity positions.
> CIK 1142206. Latest filing Q1 2026, as of quarter end 2026-03-31. Long-equity book $3.9B.

## Top holdings (teaser)

| # | Ticker | Issuer | Value | % of book | Change |
|---|--------|--------|-------|-----------|--------|
| 1 | n/a | W. R. Berkley Corporation | $3.9B | 100.0% | Added |

## Latest moves

Bought: W. R. Berkley Corporation
Sold: none this quarter

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/1142206/000119312526222668/
- Human page: https://arkolith.com/fund/mitsui-sumitomo-insurance-co-ltd-1142206
- 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._