---
schema_version: "secwatch.filing_event.v1"
accession: "0001628280-26-005947"
form_type: "8-K"
ticker: "WTM"
cik: "0000776867"
company_name: "WHITE MOUNTAINS INSURANCE GROUP LTD"
filed_at: "2026-02-06T23:59:59+00:00"
generated_at: "2026-05-16T04:12:56.031247+00:00"
event_type: "earnings"
sentiment: "positive"
materiality_score: 0.8
calibrated_materiality_score: 0.8
confidence: "high"
source: SEC EDGAR
---

# White Mountains Q4 BVPS +18%, full-year +25%; Bamboo sale adds ~$320

## Summary
- Book value per share $2,188 at Dec 31, 2025, up 18% QoQ and 25% YoY including dividends.
- Comprehensive income $837M in Q4 and $1,109M full-year 2025 vs. losses of $131M and $230M in prior year.
- Ark combined ratio 79% Q4 (10 pts cat) and 83% full-year; GWP +16% to $2.6B.
- Closed sale of Bamboo to CVC for net cash $848M; retained 15% equity stake valued at $250M.
- Repurchased ~$190M of shares in Q4 via open market and self-tender; undeployed capital ~$1.0B.

## SEC filing metadata
- accession: 0001628280-26-005947
- form_type: 8-K
- ticker: WTM
- cik: 0000776867
- company_name: WHITE MOUNTAINS INSURANCE GROUP LTD
- filed_at: 2026-02-06T23:59:59+00:00
- event_type: earnings
- sentiment: positive
- materiality_score: 0.8
- calibrated_materiality_score: 0.8
- confidence: high
- sec_items: 2.02, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/776867/000162828026005947/0001628280-26-005947-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/776867/000162828026005947/wtm-20260206.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001628280-26-005947
- JSON: https://secwatch.observer/filing/0001628280-26-005947.json
- Plain text: https://secwatch.observer/filing/0001628280-26-005947.txt

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