---
schema_version: "secwatch.filing_event.v1"
accession: "0000776867-22-000017"
form_type: "8-K"
ticker: "WTM"
cik: "0000776867"
company_name: "WHITE MOUNTAINS INSURANCE GROUP LTD"
filed_at: "2022-12-21T23:59:59+00:00"
generated_at: "2026-06-21T01:12:22.978982+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.7
calibrated_materiality_score: 0.7
confidence: "high"
source: SEC EDGAR
---

# White Mountains leads $250M reinsurance sidecar Outrigger Re for Ark

## Summary
- Outrigger Re Ltd. formed as a Bermuda special purpose insurer with $250M total capital.
- White Mountains contributes $205M; Aquiline Capital and Enstar (ESGR) join as investors.
- Sidecar provides quota-share reinsurance on Ark Bermuda's global property catastrophe portfolio.
- Coverage effective January 1, 2023, capitalizing on hard property cat reinsurance market.
- TigerRisk acted as structuring agent; Sidley Austin and Conyers Dill provided legal counsel.

## SEC filing metadata
- accession: 0000776867-22-000017
- form_type: 8-K
- ticker: WTM
- cik: 0000776867
- company_name: WHITE MOUNTAINS INSURANCE GROUP LTD
- filed_at: 2022-12-21T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.7
- calibrated_materiality_score: 0.7
- confidence: high
- sec_items: 8.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/776867/000077686722000017/0000776867-22-000017-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/776867/000077686722000017/wtm-20221221.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0000776867-22-000017
- JSON: https://secwatch.observer/filing/0000776867-22-000017.json
- Plain text: https://secwatch.observer/filing/0000776867-22-000017.txt

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