White Mountains released fourth-quarter 2025 results for its property and casualty reinsurance unit Ark/WM Outrigger, with gross written premiums (GWP) of $268 million and a combined ratio of 77%.
GWP increased slightly in the fourth quarter of 2025 compared to $264 million in the fourth quarter of 2024, while the combined ratio for the quarter was the same as the same period last year.
For the full year of 2025, Ark/WM Outrigger’s GWP was $2.557 billion, an increase from $2.207 billion the previous year, and the combined ratio improved to 81%, compared with 82% in 2024.
Net written premiums for the fourth quarter of 2024 were $218 million and $1.812 billion for the full year. Net premiums earned in the fourth quarter and full year of 2025 will reach US$433 million and US$1.697 billion respectively.
In comparison, for the fourth quarter and full year ended December 31, 2024, net premiums written were $239 million and $16.79 billion, respectively, and net premiums earned were $415 million and $1.588 billion, respectively.
Ark’s combined ratio for the fourth quarter of 2025 was 79%, compared with a reported combined ratio of 77% for the fourth quarter of 2024. CoR for the quarter included 10 percentage points of catastrophic losses, primarily caused by Hurricane Melissa.
In 2025, Ark’s CoR is 83%, the same as the previous year. The 4Q25 CoR includes eight catastrophe loss points, primarily caused by Hurricane Melissa, as well as losses related to the January 2025 California wildfires.
Ark’s combined ratio for the year ended December 31, 2025 includes 7 points of net favorable development value from the prior year, including 10 points recorded in the fourth quarter. This favorable development was primarily driven by the real estate and specialty business lines.
However, these results were partially offset by aviation losses from the conflicts in Ukraine and Russia, which amounted to 6 percentage points for the full year and 11 percentage points in the fourth quarter.
Ark’s pre-tax income for the fourth quarter and full year ended December 31, 2025 was reported to be $25 million and $265 million, respectively. This compares to pre-tax income of $51 million for the fourth quarter of 2024 and $253 million for the full year ended December 31, 2024.
Ian Beaton, chief executive of Ark, said: “Ark delivered strong quarterly and annual performance, with combined ratios of 79% and 83% respectively. With the help of its new underwriting team and products, total written premiums for the year reached $2.6 billion, up 16% year-on-year.
“In November, AM Best affirmed Ark’s financial strength rating of ‘A/Stable’ and upgraded its issuer credit rating to ‘a+/Stable’. Although the overall interest rate environment is softening, we continue to see opportunities to generate strong returns in 2026.”
WM Outrigger Re’s combined ratio improved to 41% in the fourth quarter of 2025, compared with 86% in the year-ago period. Full-year CoR was 57%, a slight improvement from 2024’s 60%.
Catastrophe losses for the year ended December 31, 2025 included $19 million in losses related to the California wildfires.
Reinsurance Sidecar also generated pre-tax income of $15 million in the fourth quarter of 2025, all of which was attributable to the 2025 underwriting year. This compares to pre-tax income of $6 million in the fourth quarter of 2024, with $2 million attributable to the 2024 underwriting year and $4 million attributable to the 2023 underwriting year.
In 2025, WM Outrigger Re reported pre-tax income of $45 million, with $55 million attributable to the 2025 underwriting year and a loss of $10 million attributable to the 2024 underwriting year.
