---
schema_version: "secwatch.filing_event.v1"
accession: "0000776867-25-000012"
form_type: "8-K"
ticker: "WTM"
cik: "0000776867"
company_name: "WHITE MOUNTAINS INSURANCE GROUP LTD"
filed_at: "2025-07-18T23:59:59+00:00"
generated_at: "2026-05-18T05:52:42.386543+00:00"
event_type: "other_material"
sentiment: "neutral"
materiality_score: 0.6
calibrated_materiality_score: 0.6
confidence: "high"
source: SEC EDGAR
---

# White Mountains closes $150M strategic investment in BroadStreet Partners

## Summary
- White Mountains invested $150M in BroadStreet as part of a group led by Ethos Capital, BCI, and T. Rowe Price.
- Ontario Teachers' retains a significant co-control stake and continues partnership with the Ethos-led group.
- BroadStreet is a middle-market insurance brokerage offering commercial and personal P&C and employee benefits solutions.
- Investment aims to support BroadStreet's Core Agency Partners with M&A, capital solutions, and digital transformation tools.

## SEC filing metadata
- accession: 0000776867-25-000012
- form_type: 8-K
- ticker: WTM
- cik: 0000776867
- company_name: WHITE MOUNTAINS INSURANCE GROUP LTD
- filed_at: 2025-07-18T23:59:59+00:00
- event_type: other_material
- sentiment: neutral
- materiality_score: 0.6
- calibrated_materiality_score: 0.6
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/776867/000077686725000012/0000776867-25-000012-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/776867/000077686725000012/wtm-20250718.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0000776867-25-000012
- JSON: https://secwatch.observer/filing/0000776867-25-000012.json
- Plain text: https://secwatch.observer/filing/0000776867-25-000012.txt

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