White Mountains Insurance Group delivered a sharp earnings rebound in 2025, reporting comprehensive income attributable to common shareholders of $837 million in Q4 and $1.109 billion for the full year, versus a loss of $131 million in Q4 2024 and income of $230 million in the prior year.
Across the health insurance sector, 2025 results were generally solid but more incremental, as carriers managed higher utilization and medical inflation against disciplined pricing. White Mountains’ trajectory was far steeper, driven by sizable capital gains, strong underwriting performance, and robust investment returns.
Book value, capital actions, and sector context
Book value per share (BVPS) rose to $2,188 as of December 31, 2025, up 18% in Q4 and 25% for the year, including dividends. The largest single driver was the sale of California‑focused MGA Bamboo, which added roughly $320 per share to BVPS and generated a net gain of $816 million for the year after compensation costs. Excluding MediaAlpha, the investment portfolio returned 2.0% in Q4 and 8.9% for 2025, while the consolidated portfolio returned 2.3% and 9.1%, respectively.
By contrast, health insurers’ 2025 earnings leaned more heavily on recurring premium and fee income than on crystallized gains. White Mountains’ year had more of a capital‑allocator profile, using M&A and portfolio rotation to unlock value and amplify investment upside.
CEO Liam Caffrey described 2025 as “an excellent year,” citing the Bamboo transaction, “solid results” from operating companies, and “good investment returns”. The group repurchased $193 million of stock in Q4 and $203 million over the full year, ending 2025 with around $1 billion of undeployed capital. In a market where health insurers largely focused on steady dividends and routine buybacks, that level of dry powder leaves White Mountains well placed to pursue new opportunities.
Underwriting versus health insurance trends
The Ark/WM Outrigger segment posted combined ratios of 77% in Q4 and 81% for 2025, with segment gross written premium rising to $2.557 billion from $2.207 billion in 2024. Ark alone delivered an 83% full‑year combined ratio and 16% GWP growth, absorbing catastrophe losses from Hurricane Melissa and the January 2025 California wildfires.
Health insurers in 2025 continued to manage earnings through medical cost ratios and utilization, with less exposure to event‑driven volatility. Ark/WM Outrigger’s low‑80s combined ratio demonstrates comparable margin discipline in a risk profile far more exposed to catastrophe events, while WM Outrigger Re’s combined ratio improvement to 57% for 2025 from 60% contrasts with the more gradual margin moves typical in health benefits businesses.
Diversified platforms, M&A, and investment leverage
HG Global swung from a $66 million pre‑tax loss in 2024 to $45 million of pre‑tax income in 2025, underscoring White Mountains’ exposure to municipal finance alongside traditional risk lines. Kudu Investment Management generated total revenues of $183 million, pre‑tax income of $140 million, and a 13% ROE - a level broadly in line with many leading health insurers but sourced from asset‑management and investment economics rather than health benefits.
Distinguished, acquired on Sept. 2 last year, contributed $145 million of managed premiums and $43 million of commission and fee revenue in Q4, alongside ScaleCo adjusted EBITDA of $9 million, albeit with a pre‑tax loss as integration and growth investments ramped up. As in the health insurance market, where carriers are building out care delivery and technology capabilities, White Mountains is using targeted M&A to deepen distribution and program administration, accepting near‑term earnings drag for longer‑term scale.
Bamboo, sold to CVC Capital Partners for $848 million in net cash proceeds, produced managed premiums of $766 million and MGA adjusted EBITDA of $106 million to the sale date, with White Mountains retaining a 15% fully diluted equity interest valued at $250 million. MediaAlpha’s share price increase lifted the carrying value of White Mountains’ 27% stake to $231 million, with each $1 move in the stock now shifting BVPS by around $7.
