---
schema_version: "secwatch.filing_event.v1"
accession: "0001628280-26-012417"
form_type: "8-K"
ticker: "WTM"
cik: "0000776867"
company_name: "WHITE MOUNTAINS INSURANCE GROUP LTD"
filed_at: "2026-02-26T23:59:59+00:00"
generated_at: "2026-05-15T23:57:31.416845+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.65
calibrated_materiality_score: 0.65
confidence: "high"
source: SEC EDGAR
---

# White Mountains invests $125M in Bishop Street MGA platform

## Summary
- White Mountains completed a $125M structured capital investment into Bishop Street Underwriters.
- Bishop Street is a RedBird Capital portfolio company and a diversified MGA platform.
- Bishop Street reported 2025 GWP exceeding $650M with a sub-50% portfolio loss ratio.
- White Mountains executives will join Bishop Street's board to support growth and M&A.
- Investment aims to accelerate Bishop Street's global footprint and organic expansion.

## SEC filing metadata
- accession: 0001628280-26-012417
- form_type: 8-K
- ticker: WTM
- cik: 0000776867
- company_name: WHITE MOUNTAINS INSURANCE GROUP LTD
- filed_at: 2026-02-26T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.65
- calibrated_materiality_score: 0.65
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/776867/000162828026012417/0001628280-26-012417-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/776867/000162828026012417/wtm-20260226.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001628280-26-012417
- JSON: https://secwatch.observer/filing/0001628280-26-012417.json
- Plain text: https://secwatch.observer/filing/0001628280-26-012417.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.