White Mountains has released the fourth quarter of 2025 results for its property and casualty re/insurance segment Ark/WM Outrigger, revealing gross written premiums (GWP) of $268 million, with a combined ratio of 77%.
GWP in Q4 2025 increased slightly compared to Q4 2024’s $264 million, while the quarter’s combined ratio remained the same as the prior year’s quarter.
For the full year 2025, Ark/WM Outrigger saw $2.557 billion in GWP, which increased from $2.207 billion the year prior, and an improved combined ratio of 81%, which compares to 2024’s 82%.
Net written premiums for Q4 2024 stood at $218 million and $1.812 billion for the full year. Net earned premiums hit $433 million and $1.697 billion in the fourth quarter and full year 2025, respectively.
These compare to net written premiums of $239 million and $1.679 bmillion, and net earned premiums of $415 million and $1.588 billion in the fourth quarter and year ended December 31, 2024, respectively.
Ark’s combined ratio was 79% in Q4 2025, compared to the 77% reported for Q4 2024. The quarter’s CoR included 10 points of catastrophe losses, driven primarily by Hurricane Melissa.
For 2025, Ark saw a CoR of 83%, same as the year prior. The Q4’25 CoR included eight points of catastrophe losses, driven primarily by Hurricane Melissa and losses related to the January 2025 California wildfires.
Ark’s combined ratio for the year ended December 31, 2025, included seven points of net favourable prior year development, with 10 points recorded in the fourth quarter. This favourable development was primarily driven by property and specialty lines of business.
However, these results were partially offset by unfavourable development related to aviation losses from the conflict in Ukraine and Russia, which amounted to six points for the full year and 11 points in the fourth quarter.
Ark’s pre-tax income for Q4 and the full year ended December 31, 2025, was reported at $25 million and $265 million, respectively. This compares to pre-tax income of $51 million for Q4 2024 and $253 million for the full year ended December 31, 2024.
Ian Beaton, CEO of Ark, said: “Ark had a good quarter and year, producing combined ratios of 79% and 83%, respectively. Full year gross written premiums reached $2.6 billion, up 16% year-over-year, aided by new underwriting teams and products.
“In November, A.M. Best affirmed Ark’s ‘A/stable’ financial strength rating and upgraded its issuer credit rating to “a+/stable”. Although the overall rate environment is softening, we continue to see opportunities to generate strong returns in 2026.”
At 41%, WM Outrigger Re saw an improved combined ratio in Q4 2025, compared to the 86% seen in the same period last year. For the full year, the CoR stood at 57%, a slight improvement compared to 2024’s 60%.
Catastrophe losses in the year ended December 31, 2025 included $19 million of losses related to the California wildfires.
The reinsurance sidecar also saw pre-tax income of $15 million in Q4 2025 all of which was attributable to the 2025 underwriting year. Comparably, pre-tax income in Q4 2024 stood at $6 million, of which $2 million was attributable to the 2024 underwriting year and $4 million was attributable to the 2023 underwriting year.
For 2025, WM Outrigger Re reported pre-tax income of $45 million, of which $55 million was attributable to the 2025 underwriting year and a loss of $10 million was attributable to the 2024 underwriting year.
