---
schema_version: "secwatch.filing_event.v1"
accession: "0001628280-25-055702"
form_type: "8-K"
ticker: "WTM"
cik: "0000776867"
company_name: "WHITE MOUNTAINS INSURANCE GROUP LTD"
filed_at: "2025-12-08T23:59:59+00:00"
generated_at: "2026-05-16T14:09:07.737246+00:00"
event_type: "m_and_a"
sentiment: "positive"
materiality_score: 0.7
calibrated_materiality_score: 0.7
confidence: "high"
source: SEC EDGAR
---

# White Mountains completes sale of controlling Bamboo stake to CVC for $848M net cash

## Summary
- Sold 77.3% equity interest in Bamboo Group for $848M net cash proceeds at closing on Dec 5, 2025.
- Retained indirect equity interest valued at $250M (approx 15% fully-diluted stake).
- Bamboo enterprise value on a cash-free/debt-free basis was $1.75B.
- Pro forma net transaction gain after tax estimated at $816.6M, increasing book value by $844.6M.
- Net proceeds include $3.6M held in escrow expected release in H1 2026.

## SEC filing metadata
- accession: 0001628280-25-055702
- form_type: 8-K
- ticker: WTM
- cik: 0000776867
- company_name: WHITE MOUNTAINS INSURANCE GROUP LTD
- filed_at: 2025-12-08T23:59:59+00:00
- event_type: m_and_a
- sentiment: positive
- materiality_score: 0.7
- calibrated_materiality_score: 0.7
- confidence: high
- sec_items: 2.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/776867/000162828025055702/0001628280-25-055702-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/776867/000162828025055702/wtm-20251205.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001628280-25-055702
- JSON: https://secwatch.observer/filing/0001628280-25-055702.json
- Plain text: https://secwatch.observer/filing/0001628280-25-055702.txt

## Source-grounded claims
- claim_id: 00643f95510c888f35d32edf7d2bf4de729041cb
  claim: WHITE MOUNTAINS INSURANCE GROUP LTD completed a disposition involving affiliates of funds advised by CVC Capital Partners for net cash proceeds at closing of $848 million and retained an indirect equity interest valued at $250 million (closed 2025-12-05).
  evidence_excerpt: the terms of the Bamboo SPA, a wholly owned subsidiary of White Mountains sold approximately 77.3% of its equity interest in the Bamboo Group for net cash proceeds at closing of $848 million and retained an indirect equity interest valued at $250 million (the “Bamboo Sale Transaction”). --- EX-99.1 (EX-99.1) --- PRESS RELEASE - White Mountains Completes Sale of
  evidence_url: https://www.sec.gov/Archives/edgar/data/776867/000162828025055702/0001628280-25-055702-index.htm

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