---
schema_version: "secwatch.filing_event.v1"
accession: "0001628280-26-030930"
form_type: "8-K"
ticker: "WTM"
cik: "0000776867"
company_name: "WHITE MOUNTAINS INSURANCE GROUP LTD"
filed_at: "2026-05-06T23:59:59+00:00"
generated_at: "2026-05-14T23:02:48.466987+00:00"
event_type: "earnings"
sentiment: "negative"
materiality_score: 0.8
calibrated_materiality_score: 0.8
confidence: "high"
source: SEC EDGAR
---

# White Mountains Q1 book value per share down 1% to $2,170; comprehensive loss $27M

## Summary
- Book value per share $2,170, down 0.8% in quarter; comprehensive loss $(27)M vs $35M income a year ago.
- Ark/WM Outrigger combined ratio improved to 91% from 97%; Ark's 91% includes 7 pts catastrophe losses from Iran war.
- Kudu adjusted EBITDA $17M, trailing 12-mo ROE 12%; HG Global gross written premiums up 24% to $8M.
- MediaAlpha carrying value fell to $166M from $231M at year-end due to share price drop to $9.30.
- Deployed $125M into Bishop Street Underwriters; two WTM Partner acquisitions in Q2 (BaseSix ~$97M, Hawkeye ~$35M).

## SEC filing metadata
- accession: 0001628280-26-030930
- form_type: 8-K
- ticker: WTM
- cik: 0000776867
- company_name: WHITE MOUNTAINS INSURANCE GROUP LTD
- filed_at: 2026-05-06T23:59:59+00:00
- event_type: earnings
- sentiment: negative
- 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/776867/000162828026030930/0001628280-26-030930-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/776867/000162828026030930/wtm-20260506.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001628280-26-030930
- JSON: https://secwatch.observer/filing/0001628280-26-030930.json
- Plain text: https://secwatch.observer/filing/0001628280-26-030930.txt

## Source-grounded claims
- claim_id: de2a6a0bb5165bd954ca7042684cb2603d446904
  claim: WHITE MOUNTAINS INSURANCE GROUP LTD reported financial results for the three months ended March 31, 2026.
  evidence_excerpt: On May 6, 2026 , White Mountains Insurance Group, Ltd. issued a press release announcing its results for the three months ended March 31, 2026.
  evidence_url: https://www.sec.gov/Archives/edgar/data/776867/000162828026030930/0001628280-26-030930-index.htm

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