WHITE MOUNTAINS INSURANCE GROUP LTD 8-K

What Happened White Mountains Insurance Group (NYSE: WTM) filed an 8-K on January 7, 2026 to announce that its specialty reinsurance unit, Ark Insurance Holdings Limited (“Ark”), renewed Outrigger Re Ltd. (“Outrigger”) for business incepting during calendar year 2026. Outrigger, a collateralized reinsurance sidecar, entered a quota share with Ark Bermuda to cover a portion of Ark Bermuda’s global property catastrophe portfolio on terms similar to 2025.

Key Details

• Outrigger deployed $70 million of total investor capital for the 2026 underwriting year.
• All $70 million was provided by third‑party investors; White Mountains did not provide this capital.
• The renewal is on similar terms to the 2025 arrangement.
• Outrigger’s size was reduced for 2026 due to Ark increasing its use of traditional quota share reinsurance.

Why It Matters This filing shows continued third‑party investor participation in Ark’s collateralized reinsurance programs, but at a smaller sidecar scale for 2026. For investors, the renewal affects Ark’s reinsurance capacity and how catastrophe risk is shared—more risk is being transferred via traditional quota shares and less via the Outrigger sidecar. The item is an “Other Event” (Item 8.01) and does not report earnings or executive changes.