WHITE MOUNTAINS INSURANCE GROUP LTD

RESULTS OF OPERATIONS FOR THE YEARS ENDED DECEMBER 31, 2025, 2024 AND 2023

Overview—Year Ended December 31, 2025 versus Year Ended December 31, 2024

White Mountains ended 2025 with book value per share of $2,188, an increase of 25% for the year, including dividends.

The increase in book value per share was driven primarily by the net gain on sale of the Bamboo Group of approximately $320 per share (based on 2.54 million shares outstanding at December 5, 2025). In addition, the growth in White Mountains’s book value per share reflected solid results at its operating companies and good investment returns.

Comprehensive income attributable to common shareholders was $1,109 million in 2025, largely driven by the net gain on sale of the Bamboo Group, compared to $230 million in 2024. White Mountains also recognized a net deferred tax expense of $73 million in 2025 from the reversal of the deferred tax asset related to the Bermuda economic transition adjustment, of which $51 million was recorded at Ark and $22 million was recorded at HG Global. Due to the enactment of Pillar II legislation by Luxembourg in December 2025, White Mountains no longer expects to utilize the benefit of the Bermuda economic transition adjustment.

On December 5, 2025, White Mountains completed the sale of a controlling financial interest in the Bamboo Group to affiliates of funds advised by CVC. White Mountains sold approximately 77.3% of its equity interest in the Bamboo Group for net cash proceeds at closing of $848 million and retained an indirect equity interest valued at $250 million. White Mountains’s Other Operations recognized a net gain of $816 million, which was comprised of an $849 million net gain on sale of the Bamboo Group, partially offset by $33 million of parent company compensation costs recorded within general and administrative expenses.

On September 2, 2025, White Mountains closed its transaction to acquire a controlling financial interest in Distinguished, a full-service MGA and program administrator for specialty property & casualty insurance. White Mountains paid $225 million of cash consideration, including a post-closing purchase price adjustment of $1 million. In addition, Distinguished borrowed $50 million of incremental debt and utilized $7 million of cash on hand as part of the transaction.

On July 18, 2025, White Mountains closed its transaction to deploy $150 million into BroadStreet through the BroadStreet SPV, alongside co-lead investors Ethos Capital LP and British Columbia Investment Management Corporation. BroadStreet is an insurance brokerage company with a presence in all 50 U.S. states and ten Canadian provinces.

On April 1, 2025, White Mountains acquired a majority interest in Enterprise Solutions, a provider of specialty electrical contracting services. This was the first acquisition by WTM Partners. White Mountains paid $58 million of cash consideration, and Enterprise Solutions borrowed $15 million in new debt as part of the transaction.

In 2025, White Mountains repurchased and retired 100,581 of its common shares for $203 million at an average share price of $2,013.67, or 92% of White Mountains’s December 31, 2025 book value per share. This included 64,064 shares repurchased through the self-tender offer in December.

Including a distribution of $128 million from WM Outrigger Re received in January, undeployed capital stands at roughly $1.0 billion.

The Ark/WM Outrigger segment’s combined ratio was 81% in 2025 compared to 82% in 2024. The Ark/WM Outrigger segment reported gross written premiums of $2,557 million, net written premiums of $1,812 million and net earned premiums of $1,697 million in 2025 compared to gross written premiums of $2,207 million, net written premiums of $1,679 million and net earned premiums of $1,588 million in 2024. The Ark/WM Outrigger segment reported pre-tax income of $310 million in 2025 compared to $299 million in 2024.

Ark’s combined ratio was 83% in both 2025 and 2024. Ark’s combined ratio in 2025 included eight points of catastrophe losses, driven primarily by Hurricane Melissa and losses related to the January 2025 California wildfires, compared to 13 points of catastrophe losses in 2024, driven primarily by Hurricanes Milton, Helene, Debby and Beryl. Ark’s combined ratio included seven points of net favorable prior year development in 2025, driven primarily by property and specialty lines of business. This included six points of unfavorable development related to aviation losses from the conflict in Ukraine and Russia. This compares to four points of net favorable prior year development in 2024, driven primarily by property and specialty lines of business.

Ark reported gross written premiums of $2,557 million, net written premiums of $1,727 million and net earned premiums of $1,613 million in 2025 compared to gross written premiums of $2,207 million, net written premiums of $1,593 million and net earned premiums of $1,500 million in 2024. Ark reported pre-tax income of $265 million in 2025 compared to $253 million in 2024. Ark’s results included net realized and unrealized investment gains of $125 million in 2025 compared to $50 million in 2024. Ark’s results in 2025 also included a $173 million of expense related to the increase in fair value of contingent consideration compared to $61 million in 2024. The increase in the contingent consideration liability was driven primarily by strong growth in Ark’s tangible book value in the year. Ark’s results in 2025 also included the reversal of the $51 million deferred tax asset associated with the Bermuda economic transition adjustment. In November 2025, A.M. Best affirmed Ark’s “A/stable” financial strength rating and upgraded its issuer credit rating to “a+/stable”.

WM Outrigger Re’s combined ratio was 57% in 2025, compared to 60% in 2024. Catastrophe losses in the year ended December 31, 2025 included $19 million of losses related to the California wildfires (net of reinstatement premiums), primarily attributable to the 2024 underwriting year. WM Outrigger Re reported gross written premiums of $84 million and net earned premiums of $85 million in 2025 compared to gross written premiums of $87 million and net earned premiums of $88 million in 2024.

WM Outrigger Re reported pre-tax income (loss) of $45 million in 2025, of which $55 million was attributable to the 2025 underwriting year and $(10) million was attributable to the 2024 underwriting year. WM Outrigger Re reported pre-tax income of $46 million in 2024, of which $38 million was attributable to the 2024 underwriting year and $8 million was attributable to the 2023 underwriting year. Through December 31, 2025, WM Outrigger Re has generated pre-tax income of $55 million from the 2025 underwriting year, $29 million from the 2024 underwriting year and $76 million from the 2023 underwriting year.

White Mountains’s capital commitment to WM Outrigger Re was $150 million for the 2025 underwriting year, $130 million for the 2024 underwriting year and $205 million for the 2023 underwriting year. During the fourth quarter of 2025, Ark renewed Outrigger Re Ltd. for the 2026 underwriting year with $70 million of capital. The capital was provided entirely by third-party investors excluding White Mountains.

HG Global reported gross written premiums and earned premiums of $61 million and $31 million in 2025 compared to $52 million and $29 million in 2024. HG Global’s total par value of policies assumed was $3,170 million in 2025 compared to $2,952 million in 2024. HG Global’s total gross pricing was 194 basis points in 2025 compared to 177 basis points in 2024. HG Global reported pre-tax income (loss) of $45 million in 2025 compared to $(66) million in 2024. HG Global’s results included net realized and unrealized investment gains (losses) of $23 million in 2025 compared to $(6) million in 2024, driven by movements in interest rates. HG Global’s results in 2025 also included the reversal of the $22 million deferred tax asset associated with the Bermuda economic transition adjustment. HG Global’s results in 2025 included a $38 million decline in the fair value of the BAM surplus notes, which was driven by changes in certain key inputs used in the discounted cash flow analysis. HG Global’s results in 2024 included an increase of $1 million in the fair value of the BAM surplus notes. In addition, HG Global’s results in 2024 included the $115 million unrealized loss on deconsolidation of BAM.

The fair value of the BAM Surplus Notes was $339 million as of December 31, 2025 compared to $382 million as of December 31, 2024. The decline was driven by the $38 million decrease in fair value and $35 million in cash payments of principal and interest, partially offset by approximately $30 million of accrued interest.

Kudu reported total revenues of $183 million, pre-tax income of $140 million and adjusted EBITDA of $65 million in 2025 compared to total revenues of $119 million, pre-tax income of $81 million and adjusted EBITDA of $55 million in 2024. Total revenues, pre-tax income and adjusted EBITDA included $79 million of net investment income in 2025 compared to $67 million in 2024. Total revenues and pre-tax income also included $104 million of net realized and unrealized investment gains in 2025 compared to $51 million in 2024.

Kudu deployed $197 million, including transaction costs, into three new asset management firms in 2025. As of December 31, 2025, Kudu has deployed $1.2 billion, including transaction costs, into 30 asset and wealth management firms globally, including three that have been exited. As of December 31, 2025, the asset and wealth management firms have combined assets under management of approximately $153 billion, spanning a range of asset classes.

Bamboo reported commission and fee revenues of $211 million and pre-tax income of $40 million in the period from January 1, 2025 through December 5, 2025, the date of sale, while Bamboo reported commission and fee revenues of $135 million and pre-tax income of $33 million in 2024. Bamboo reported MGA pre-tax income of $41 million and MGA adjusted EBITDA of $91 million in the period from January 1, 2025 through December 5, 2025, while Bamboo reported MGA pre-tax income of $32 million and MGA adjusted EBITDA of $53 million in 2024. Managed premiums, which represent the total premium placed by Bamboo, were $705 million in the period from January 1, 2025 through December 5, 2025 and $484 million in 2024. The increase in managed premiums was driven by growth in the renewal book as well as new business volume.

For the period from September 2, 2025, the date of acquisition, through December 31, 2025, Distinguished reported

managed premiums of $188 million, commission and fee revenues of $57 million, pre-tax loss of $17 million and ScaleCo

adjusted EBITDA of $9 million.

As of December 31, 2025, White Mountains owned 17.9 million shares of MediaAlpha, representing a 27.4% basic ownership interest based on the total class A and class B common shares outstanding in MediaAlpha’s Report on Form 10-Q dated October 29, 2025. As of December 31, 2025, MediaAlpha’s share price was $12.95 per share, which increased from $11.29 per share as of December 31, 2024. The carrying value of White Mountains’s investment in MediaAlpha was $231 million as of December 31, 2025, which increased from $202 million as of December 31, 2024. At White Mountains’s current level of ownership, each $1.00 per share increase or decrease in the stock price of MediaAlpha will result in an approximate $7.00 per share increase or decrease in White Mountains’s book value per share.

White Mountains’s total consolidated portfolio return on invested assets was 9.1% in 2025, which included $30 million of unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the total consolidated portfolio return on invested assets was 8.9% in 2025. Excluding MediaAlpha, investment returns in 2025 were driven primarily by net investment income and net unrealized investment gains from other long-term investments, net investment income from the fixed income portfolio and net realized gains from common equity securities.

White Mountains’s total consolidated portfolio return on invested assets was 6.9% in 2024, which included $38 million of

net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the

total consolidated portfolio return on invested assets was 6.5% in 2024. Excluding MediaAlpha, investment returns in 2024

were driven primarily by net investment income and net realized and unrealized investment gains from other long-term investments, net investment income from the fixed income portfolio and net unrealized gains from common equity securities.

Overview—Year Ended December 31, 2024 versus Year Ended December 31, 2023

White Mountains ended 2024 with book value per share of $1,746, an increase of 6% for the year, including dividends. Comprehensive income attributable to common shareholders was $230 million in 2024 compared to $511 million in 2023.

Results in 2024 were driven primarily by solid results from White Mountains’s operating businesses and good returns in the investment portfolio. Results in 2023 were driven primarily by good results from White Mountains’s operating businesses and strong returns in the investment portfolio. White Mountains’s results included net realized and unrealized investment gains of $147 million in 2024 compared to $407 million in 2023. Results in 2024 also included $38 million of net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha compared to $27 million in 2023.

As of December 31, 2024, White Mountains’s undeployed capital was approximately $0.7 billion, including the net proceeds received from the debt recapitalization completed in January 2025 at Bamboo.

Ark’s combined ratio was 83% in 2024, compared to 82% in 2023. Ark’s combined ratio included 13 points of catastrophe losses in 2024, driven primarily by Hurricanes Milton, Helene, Debby and Beryl, compared to two points of catastrophe losses in 2023, driven primarily by Hurricanes Otis and Idalia as well as the Maui wildfires. The combined ratio in 2024 included four points of net favorable prior year loss reserve development, driven primarily by specialty and property lines of business, compared to two points of net unfavorable prior year loss reserve development in 2023, driven primarily by Hurricane Ian and Winter Storm Elliott.

Ark reported gross written premiums of $2,207 million, net written premiums of $1,593 million and net earned premiums of $1,500 million in 2024 compared to gross written premiums of $1,898 million, net written premiums of $1,411 million and net earned premiums of $1,305 million in 2023. Ark reported pre-tax income of $253 million in 2024 compared to $249 million in 2023. Ark’s results in 2023 included a $51 million net deferred tax benefit related to the Bermuda economic transition adjustment. In November 2024, AM Best affirmed Ark’s financial strength rating at “A/stable.”

WM Outrigger Re’s combined ratio was 60% in 2024, compared to 44% in 2023. The 2024 combined ratio included catastrophe losses from Hurricanes Milton, Helene, Debby and Beryl. Major catastrophe losses affecting WM Outrigger Re in 2023 were minimal. WM Outrigger Re reported gross and net written premiums of $87 million, net earned premiums of $88 million and pre-tax income of $46 million in 2024, compared to gross and net written premiums of $110 million, net earned premiums of $104 million and pre-tax income of $69 million in 2023. Net earned premiums in 2024 decreased due to White Mountains’s lower capital commitment to WM Outrigger Re in 2024 compared to 2023. During the fourth quarter of 2024, Ark renewed Outrigger Re Ltd. for the 2025 underwriting year. White Mountains’s total commitment toward the 2025 underwriting year is $150 million.

As of July 1, 2024, White Mountains no longer consolidates BAM. Upon deconsolidation, the BAM Surplus Notes, including accrued interest receivable, were fair valued in accordance with GAAP at $387 million, which resulted in an unrealized loss on deconsolidation of $115 million. As of December 31, 2024, the BAM Surplus Notes were fair valued at $382 million. The decrease in fair value of $5 million was driven by a $22 million cash payment of principal and interest, partially offset by $16 million of accrued interest and a $1 million increase in fair value as a result of lower market interest rates.

HG Global reported gross written premiums and earned premiums of $52 million and $29 million in 2024 compared to $50 million and $26 million in 2023. HG Global reported gross written premiums net of ceding commission paid of $37 million in 2024 compared to $35 million in 2023. HG Global’s total par value of policies assumed, which represents its first-loss exposure on policies assumed from BAM, was $2,952 million in 2024 compared to $2,356 million in 2023. HG Global’s total gross pricing was 177 basis points in 2024 compared to 213 basis points in 2023.

Kudu reported total revenues of $119 million, pre-tax income of $81 million and adjusted EBITDA of $55 million in 2024 compared to total revenues of $177 million, pre-tax income of $137 million and adjusted EBITDA of $57 million in 2023. Total revenues and pre-tax income in 2024 included $67 million of net investment income and $51 million of net realized and unrealized investment gains compared to $71 million and $106 million in 2023.

Kudu deployed $104 million, including transaction costs, into two new asset management firms in 2024. As of December 31, 2024, Kudu had deployed $989 million, including transaction costs, into 27 asset and wealth management firms globally, including three that have been exited. As of December 31, 2024, the asset and wealth management firms have combined assets under management of approximately $125 billion, spanning a range of asset classes.

Bamboo reported commission and fee revenues of $135 million and pre-tax income of $33 million in 2024. Bamboo reported MGA pre-tax income of $32 million and MGA adjusted EBITDA of $53 million in 2024. Managed premiums, which represent the total premium placed by Bamboo, were $484 million in 2024 compared to $215 million in 2023 (prior to White Mountains’s ownership of Bamboo). The increase in managed premiums was driven by growth in new business volume as well as a growing renewal book.

On May 10, 2024, MediaAlpha completed a secondary offering of 7.6 million shares at $19.00 per share ($18.24 per share net of underwriting fees). In the secondary offering, White Mountains sold 5.0 million shares for net proceeds of $91 million.

As of December 31, 2024, White Mountains owned 17.9 million shares of MediaAlpha, representing a 26.6% basic ownership interest. As of December 31, 2024, MediaAlpha’s share price was $11.29, which increased from $11.15 per share as of December 31, 2023. The carrying value of White Mountains’s investment in MediaAlpha was $202 million as of December 31, 2024, which decreased from $255 million as of December 31, 2023 as a result of the secondary offering.

White Mountains’s total consolidated portfolio return on invested assets was 6.9% in 2024, which included $38 million of net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the total consolidated portfolio return on invested assets was 6.5% in 2024. Excluding MediaAlpha, investment returns in 2024 were driven primarily by net investment income and net realized and unrealized investment gains from other long-term investments, net investment income from the fixed income portfolio and net unrealized gains from common equity securities.

White Mountains’s total consolidated portfolio return on invested assets, both including and excluding White Mountains’s investment in MediaAlpha, was 11.4% in 2023. The total consolidated portfolio return included $27 million of unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, investment returns in 2023 were driven primarily by net investment income and net realized and unrealized investment gains from the other long-term investments and fixed income portfolios.

Book Value Per Share

The following table presents White Mountains’s book value per share as of December 31, 2025, 2024 and 2023:

Goodwill and Other Intangible Assets

The following table presents goodwill and other intangible assets that are included in White Mountains’s book value as of December 31, 2025, 2024 and 2023:

(1)The relative fair values of goodwill and other intangible assets recognized in connection with the Distinguished Transaction and the Enterprise Solutions Transaction have not yet been finalized. See Note 2 — “Significant Transactions”on page F-19.

(2)See Note 4 — “Goodwill and Other Intangible Assets” on page F-34 for details of other intangible assets.

(3) Amounts reflect the basic ownership percentage of the noncontrolling shareholders.

Summary of Consolidated Results

The following table presents White Mountains’s consolidated financial results by industry for the years ended December 31, 2025, 2024 and 2023:

I. SUMMARY OF OPERATIONS BY SEGMENT

As of December 31, 2025, White Mountains conducted its operations through four reportable segments: (1) Ark/WM Outrigger, (2) HG Global, (3) Kudu and (4) Distinguished, with our remaining operating businesses, holding companies and other assets included in Other Operations. White Mountains has made its segment determination based on consideration of the following criteria: (i) the nature of the business activities of each of the Company’s subsidiaries and affiliates; (ii) the manner in which the Company’s subsidiaries and affiliates are organized; (iii) the existence of primary managers responsible for specific subsidiaries and affiliates; and (iv) the organization of information provided to the Company’s chief operating decision makers and its Board of Directors. Significant intercompany transactions among White Mountains’s segments have been eliminated herein. White Mountains’s segment information is presented in Note 15 — “Segment Information” on page F-70.

During the fourth quarter of 2022, Ark sponsored the formation of Outrigger Re Ltd. to provide collateralized reinsurance protection on Ark’s Bermuda global property catastrophe excess of loss portfolio written in the 2023 underwriting year. Ark renewed its quota share reinsurance agreement with Outrigger Re Ltd. for the 2024, 2025 and 2026 underwriting years. White Mountains consolidates its segregated account of Outrigger Re Ltd., WM Outrigger Re, in its financial statements. WM Outrigger Re’s quota share reinsurance agreement with GAIL eliminates in White Mountains’s consolidated financial statements. WM Outrigger Re exclusively provides reinsurance protection to Ark. As a result, WM Outrigger Re was aggregated with Ark within the Ark/WM Outrigger segment starting in 2023. See Note 2 — “Significant Transactions”on page F-19.

Effective July 1, 2024, White Mountains no longer consolidates BAM. Through June 30, 2024, BAM’s results of operations, are presented within the HG Global segment. See Note 2 — “Significant Transactions” on page F-19.

On December 5, 2025, White Mountains completed the Bamboo Sale Transaction. As a result, White Mountains deconsolidated the Bamboo Group on December 5, 2025, and Bamboo is no longer a reportable segment. Through December 5, 2025, Bamboo’s results of operations, are presented within the Bamboo segment. White Mountains’s noncontrolling equity interest in the Bamboo SPV is accounted for at fair value in other long-term investments within Other Operations. See Note 2 — “Significant Transactions”on page F-19.

On September 2, 2025, White Mountains completed the Distinguished Transaction. As a result, White Mountains began consolidating Distinguished in its financial statements on September 2, 2025. See Note 2 — “Significant Transactions”on page F-19.

A discussion of White Mountains’s consolidated investment operations is included after the discussion of operations by segment.

Ark is a specialty property and casualty insurance and reinsurance company that offers a wide range of niche insurance and reinsurance products, including property, specialty, marine & energy, casualty and accident & health. Ark underwrites select coverages through its two major subsidiaries in the United Kingdom and Bermuda.

Ark sponsored the formation of Outrigger Re Ltd., a Bermuda company registered as a special purpose insurer and segregated accounts company, to provide collateralized reinsurance protection on Ark’s Bermuda global property catastrophe excess of loss portfolio. White Mountains consolidates its segregated account of Outrigger Re Ltd., WM Outrigger Re, in its financial statements.

The following tables present the components of pre-tax income (loss) included in the Ark/WM Outrigger segment for the years ended December 31, 2025, 2024 and 2023:

Combined Ratio

The following tables present the Ark/WM Outrigger segment’s insurance premiums, insurance expenses and insurance ratios for the years ended December 31, 2025, 2024 and 2023:

The following table presents WM Outrigger Re’s insurance premiums, combined ratio and pre-tax income by underwriting year for the years ended December 31, 2025, 2024 and 2023:

Through December 31, 2025, WM Outrigger Re has generated pre-tax income of $55 million from the 2025 underwriting year, $29 million from the 2024 underwriting year and $76 million from the 2023 underwriting year.

White Mountains’s capital commitment to WM Outrigger Re was $150 million for the 2025 underwriting year, $130 million for the 2024 underwriting year and $205 million for the 2023 underwriting year. During the fourth quarter of 2025, Ark renewed Outrigger Re Ltd. for the 2026 underwriting year with $70 million of capital. The reduced capacity at Outrigger Re Ltd. was replaced by Ark through traditional quota share reinsurance agreements. The capital was provided entirely by third-party investors excluding White Mountains.

Ark/WM Outrigger Results—Year Ended December 31, 2025 versus Year Ended December 31, 2024

Ark/WM Outrigger segment’s combined ratio was 81% in 2025, compared to 82% in 2024. The Ark/WM Outrigger segment reported gross written premiums of $2,557 million, net written premiums of $1,812 million and net earned premiums of $1,697 million in 2025, compared to gross written premiums of $2,207 million, net written premiums of $1,679 million and net earned premiums of $1,588 million in 2024. The Ark/WM Outrigger segment reported pre-tax income of $310 million in 2025 compared to $299 million in 2024.

Ark’s combined ratio was 83% in both 2025 and 2024. Ark’s combined ratio included eight points of catastrophe losses in 2025, driven primarily by Hurricane Melissa as well as losses related to the January 2025 California wildfires of $78 million on a net basis after reinsurance and reinstatement premiums, compared to 13 points of catastrophe losses in 2024, driven primarily by Hurricanes Milton, Helene, Debby and Beryl. Ark’s combined ratio included seven points of net favorable prior year development in 2025, driven primarily by property and specialty lines of business. This included six points of unfavorable development related to aviation losses from the conflict in Ukraine and Russia. This compares to four points of net favorable prior year development in 2024, driven primarily by property and specialty lines of business.

Ark reported gross written premiums of $2,557 million, net written premiums of $1,727 million and net earned premiums of $1,613 million in 2025, compared to gross written premiums of $2,207 million, net written premiums of $1,593 million and net earned premiums of $1,500 million in 2024. The increase in gross written premiums was driven primarily by the addition of new underwriting teams and classes of business in the property and specialty lines of business.

Ark reported pre-tax income of $265 million in 2025 compared to $253 million in 2024. Ark’s results included net realized and unrealized investment gains of $125 million in 2025, driven primarily by net unrealized investment gains on other long-term investments and common equity securities and net foreign currency gains, compared to $50 million in 2024, driven primarily by net unrealized investment gains on other long-term investments and common equity securities, partially offset by net foreign currency losses. Ark’s results in 2025 also included a $173 million increase in the fair value of contingent consideration compared to $61 million in 2024. The increase in the contingent consideration liability was driven primarily by strong growth in Ark’s tangible book value in the year. See “Contingent Consideration Liabilities” in Note 1 — “Basis of Presentation and Significant Accounting Policies”on page F-18. Ark’s results in 2025 also included the reversal of the $51 million deferred tax asset associated with the Bermuda economic transition adjustment.

WM Outrigger Re’s combined ratio was 57% in 2025, compared to 60% in 2024. Catastrophe losses in 2025 included $19 million of losses related to the California wildfires, net of reinstatement premiums. WM Outrigger Re’s losses related to the California wildfires were $2 million for the 2025 underwriting year and $17 million for the 2024 underwriting year. Catastrophe losses in 2024 included Hurricanes Milton, Helene, Debby and Beryl. In 2025, WM Outrigger Re’s combined ratio was 42% for the 2025 underwriting year and 267% for the 2024 underwriting year. In 2024, WM Outrigger Re’s combined ratio was 67% for the 2024 underwriting year and (54)% for the 2023 underwriting year.

WM Outrigger Re reported gross written premiums of $84 million and net earned premiums of $85 million in 2025, compared to gross written premiums of $87 million and net earned premiums of $88 million in 2024. WM Outrigger Re reported pre-tax income (loss) of $45 million in 2025, of which $55 million related to the 2025 underwriting year and $(10) million related to the 2024 underwriting year. WM Outrigger Re reported pre-tax income of $46 million in 2024, of which $38 million related to the 2024 underwriting year and $8 million related to the 2023 underwriting year.

Ark/WM Outrigger Results—Year Ended December 31, 2024 versus Year Ended December 31, 2023

Ark/WM Outrigger segment’s combined ratio was 82% in 2024, compared to 80% in 2023. The Ark/WM Outrigger segment reported gross written premiums of $2,207 million, net written premiums of $1,679 million and net earned premiums of $1,588 million in 2024, compared to gross written premiums of $1,898 million, net written premiums of $1,521 million and net earned premiums of $1,410 million in 2023. The Ark/WM Outrigger segment reported pre-tax income of $299 million in 2024 compared to $318 million in 2023.

Ark’s combined ratio was 83% in 2024 compared to 82% in 2023. Ark’s combined ratio included 13 points of catastrophe losses in 2024, driven primarily by Hurricanes Milton, Helene, Debby and Beryl, compared to two points of catastrophe losses in 2023, driven primarily by Hurricanes Otis and Idalia as well as the Maui wildfires. Ark’s combined ratio included four points of net favorable prior year development in 2024, driven primarily by specialty and property lines of business, compared to two points of net unfavorable prior year development in 2023, driven primarily by Hurricane Ian and Winter Storm Elliott, partially offset by net favorable prior year loss reserve development within the specialty and casualty–runoff reserving lines of business.

Ark reported gross written premiums of $2,207 million, net written premiums of $1,593 million and net earned premiums of $1,500 million in 2024, compared to gross written premiums of $1,898 million, net written premiums of $1,411 million and net earned premiums of $1,305 million in 2023.

Ark reported pre-tax income of $253 million in 2024 compared to $249 million in 2023. Ark’s results included net realized and unrealized investment gains (losses) of $50 million in 2024, driven primarily by net unrealized investment gains on other long-term investments and common equity securities, partially offset by net foreign currency losses, compared to $86 million in 2023, driven primarily by net unrealized investment gains on other long-term investments, fixed maturity investments and common equity securities. Ark’s results in 2024 also included a $61 million increase in the fair value of contingent consideration compared to $49 million in 2023. Ark’s results in 2023 included a $51 million net deferred tax benefit related to the Bermuda economic transition adjustment.

WM Outrigger Re’s combined ratio was 60% in 2024, compared to 44% in 2023. The 2024 combined ratio included catastrophe losses from Hurricanes Milton, Helene, Debby and Beryl. Major catastrophe losses affecting WM Outrigger Re in 2023 were minimal. WM Outrigger Re reported gross written premiums of $87 million and net earned premiums of $88 million in 2024, compared to gross written premiums of $110 million and net earned premiums of $104 million in 2023. Net earned premiums in 2024 decreased due to White Mountains’s lower capital commitment to WM Outrigger Re in 2024 compared to 2023. WM Outrigger Re reported pre-tax income of $46 million in 2024, compared to pre-tax income of $69 million in 2023.

Gross Written Premiums

Ark’s gross written premiums increased 16% to $2,557 million in 2025 compared to $2,207 million in 2024, with risk adjusted rate change of -4%. The increase in gross written premiums was driven primarily by the addition of new underwriting teams and classes of business in the property and specialty lines of business. The risk adjusted rate change on the Outrigger Re Ltd. portfolio of global property reinsurance was -5% in 2025.

Ark’s gross written premiums increased 16% to $2,207 million in 2024 compared to $1,898 million in 2023, with flat risk adjusted rate change. The increase in gross written premiums was across all lines of business but driven primarily by structured property transactions placed in Bermuda and the addition of new products and underwriting teams, including accident & health, marine liability and political violence. The risk adjusted rate change on the Outrigger Re Ltd. portfolio of global property reinsurance was -3% in 2024.

The following table presents Ark’s gross written premiums by line of business for the years ended December 31, 2025, 2024 and 2023:

Ark/WM Outrigger Balance Sheets

The following tables present amounts from Ark and WM Outrigger Re that are contained within White Mountains’s consolidated balance sheet as of December 31, 2025 and 2024:

(1)Amount is net of $43.9 in deferred tax liabilities related to the intangible assets.

(2)See“NON-GAAP FINANCIAL MEASURES” on page 85.

(1)Amount is net of $43.9 in deferred tax liabilities related to the intangible assets.

(2)See“NON-GAAP FINANCIAL MEASURES” on page 85.

HG Global was established to fund the startup of BAM and, through its reinsurance subsidiary HG Re, to provide up to 15%-of-par, first-loss reinsurance protection for policies underwritten by BAM.

The following tables present the components of pre-tax income (loss) included in the HG Global segment for the years ended December 31, 2025, 2024 and 2023. The HG Global segment consists of HG Global, which includes HG Re and its other wholly-owned subsidiaries, and, prior to its deconsolidation on July 1, 2024, BAM. Through June 30, 2024, BAM’s results of operations are presented within the HG Global segment.

(1)Amount includes $0.8 of intercompany revenues that are eliminated in White Mountains’s consolidated financial statements. For segment reporting, HG Global’s intercompany revenues included within the HG Global segment are eliminated against the offsetting intercompany expense included within Other Operations.

(1)Effective July 1, 2024, White Mountains no longer consolidates BAM. For the period from January 1, 2024 through June 30, 2024, BAM’s results of operations were presented within the HG Global segment.

(2)Upon the deconsolidation of BAM, the BAM Surplus Notes, including accrued interest receivable, were fair valued in accordance with GAAP at $387.4, which resulted in an unrealized loss on deconsolidation of $114.5.

(3)Amount includes $0.5 of intercompany revenues that are eliminated in White Mountains’s consolidated financial statements. For segment reporting, HG Global’s intercompany revenues included within the HG Global segment are eliminated against the offsetting intercompany expense included within Other Operations

(4)Amount includes $1.0 of intercompany interest expense that is eliminated in White Mountains’s consolidated financial statements. For segment reporting, HG Global’s intercompany interest expense included within the HG Global segment is eliminated against the offsetting intercompany interest income included within Other Operations.

(5) MSC collected are recorded directly to BAM’s equity, which was recorded as noncontrolling interests on White Mountains’s balance sheet through June 30, 2024.

(1) Amount includes $0.5 of intercompany interest expense that is eliminated in White Mountains’s consolidated financial statements. For segment reporting, HG Global’s intercompany interest expense included within the HG Global segment is eliminated against the offsetting intercompany interest income included within Other Operations.

(2) MSC collected are recorded directly to BAM’s equity, which is recorded as noncontrolling interests on White Mountains’s balance sheet.

HG Global Results—Year Ended December 31, 2025 versus Year Ended December 31, 2024

HG Global reported gross written premiums of $61 million and earned premiums of $31 million in 2025 compared to gross written premiums of $52 million and earned premiums of $29 million in 2024. HG Global reported gross written premiums net of ceding commission paid of $43 million in 2025 compared to $37 million in 2024. HG Global’s total par value of policies assumed, which represents its first-loss exposure on policies assumed from BAM, was $3,170 million in 2025, of which $2,718 million was in the primary market and $452 million in the secondary market, compared to $2,952 million in 2024, of which $2,614 million was in the primary market and $338 million in the secondary market. The increase in primary market par assumed was driven by increased municipal bond issuance. The increase in secondary market par assumed was driven by increased uncertainty in financial markets, which created more demand for bond insurance.

HG Global’s total gross pricing was 194 basis points in 2025, compared to 177 basis points in 2024. Pricing in the primary market increased to 160 basis points in 2025 compared to 140 basis points in 2024, due to an increase in the volume of large, higher-priced issuances insured by BAM in 2025. Pricing in the secondary market, which is more transaction specific than pricing in the primary market, decreased to 398 basis points in 2025 compared to 464 basis points in 2024, due to a decrease in the volume and pricing of larger secondary market issuances insured by BAM in 2025. Total pricing net of ceding commission paid increased to 136 basis points in 2025 compared to 125 basis points in 2024.

The following table presents HG Global’s par value assumed, reinsurance premiums and pricing for the years ended December 31, 2025 and 2024:

(1) For capital appreciation bonds, par is adjusted to the estimated equivalent par value for current interest paying bonds.

HG Global reported pre-tax income (loss) of $46 million in 2025 compared to $(66) million in 2024. HG Global’s results included net realized and unrealized investment gains (losses) on its fixed income portfolio of $23 million in 2025 compared to $(6) million in 2024, driven by movements in interest rates. HG Global’s results included interest income on the BAM Surplus Notes of $30 million in 2025 compared to $29 million in 2024. HG Global’s results in 2025 included a $38 million decline in the fair value of the BAM surplus notes, which was driven by changes in certain key inputs used in the discounted cash flow analysis. HG Global’s results in 2024 included an increase $1 million in the fair value of the BAM surplus notes. In addition, HG Global’s results in 2024 included the $115 million unrealized loss on deconsolidation of BAM. See Note 10 — “Municipal Bond Guarantee Insurance - BAM Surplus Notes” on page F-61. HG Global’s results in 2025 also included the reversal of the $22 million deferred tax asset associated with the Bermuda economic transition adjustment.

During 2025, HG Global received cash payments of principal and interest on the BAM Surplus Notes totaling $35 million. Of these payments, $24 million was a repayment of principal held in the Supplemental Trust, less than $1 million was a payment of accrued interest held in the Supplemental Trust and $11 million was a payment of accrued interest held outside the Supplemental Trust.

During 2024, HG Global received cash payments of principal and interest on the BAM Surplus Notes totaling $30 million. Of these payments, $21 million was a repayment of principal held in the Supplemental Trust, $1 million was a payment of accrued interest held in the Supplemental Trust and $8 million was a payment of accrued interest held outside the Supplemental Trust.

During 2025, HG Re received a distribution from the Supplemental Trust of $61 million, which consisted of an assignment of accrued interest on the BAM Surplus Notes of $30 million and a cash distribution of $31 million. During 2024, HG Re received a distribution from the Supplemental Trust of $80 million, which consisted of an assignment of accrued interest on the BAM Surplus Notes of $59 million and a cash distribution of $21 million.

HG Global Results—Year Ended December 31, 2024 versus Year Ended December 31, 2023

Effective July 1, 2024, White Mountains no longer consolidates BAM. Upon deconsolidation, the BAM Surplus Notes, including accrued interest receivable, were fair valued in accordance with GAAP at $387 million, which resulted in an unrealized loss on deconsolidation of $115 million. As of December 31, 2024, the BAM Surplus Notes were fair valued at $382 million. The decrease in fair value of $5 million was driven by a $22 million cash payment of principal and interest, partially offset by $16 million of accrued interest and a $1 million increase in fair value as a result of lower market interest rates.

HG Global reported gross written premiums of $52 million and earned premiums of $29 million in 2024 compared to gross written premiums of $50 million and earned premiums of $26 million in 2023. HG Global reported gross written premiums net of ceding commission paid of $37 million in 2024 compared to $35 million in 2023. HG Global’s total par value of policies assumed, which represents its first-loss exposure on policies assumed from BAM, was $2,952 million in 2024, of which $2,614 million was in the primary market and $338 million in the secondary market, compared to $2,356 million in 2023, of which $1,930 million was in the primary market and $426 million in the secondary market.

HG Global’s total gross pricing was 177 basis points in 2024 compared to 213 basis points in 2023. Pricing in the primary market decreased to 140 basis points in 2024 compared to 164 basis points in 2023, due to tighter municipal bond spreads and an increase in the volume of large, higher-credit issuances insured by BAM. Pricing in the secondary market, which is more transaction specific than pricing in the primary market, increased to 464 basis points in 2024 compared to 434 basis points in 2023. Total pricing net of ceding commission paid decreased to 125 basis points in 2024 compared to 148 basis points in 2023.

The following table presents HG Global’s par value assumed, reinsurance premiums and pricing for the years ended December 31, 2024 and 2023:

(1) For capital appreciation bonds, par is adjusted to the estimated equivalent par value for current interest paying bonds.

HG Global reported pre-tax income (loss) of $(66) million in 2024 compared to $56 million in 2023. The change in pre-tax income (loss) was driven primarily by the loss on deconsolidation of BAM of $115 million in 2024. HG Global’s results included net realized and unrealized investment gains (losses) on its fixed income portfolio of $(6) million in 2024 compared to $14 million in 2023, driven by movements in interest rates. HG Global’s results included interest income on the BAM Surplus Notes of $29 million in 2024 compared to $26 million in 2023. The increase in interest income is driven by an increase in the interest rate on the BAM Surplus Notes in 2024. See Note 10 — “Municipal Bond Guarantee Insurance - BAM Surplus Notes” on page F-61. HG Global’s results also included a $5 million net deferred tax benefit related to the Bermuda economic transition adjustment in 2024 compared to $17 million in 2023.

During 2024, HG Global received cash payments of principal and interest on the BAM Surplus Notes totaling $30 million. Of these payments, $21 million was a repayment of principal held in the Supplemental Trust, $1 million was a payment of accrued interest held in the Supplemental Trust and $8 million was a payment of accrued interest held outside the Supplemental Trust.

During 2023, HG Global received a cash payment of principal and interest on the BAM Surplus Notes of $27 million. Of this payment, $18 million was a repayment of principal held in the Supplemental Trust, $2 million was a payment of accrued interest held in the Supplemental Trust and $7 million was a payment of accrued interest held outside the Supplemental Trust.

During 2024, HG Re received a distribution out of the Supplemental Trust of $80 million, which was comprised of the assignment of $59 million of accrued interest on the BAM Surplus Notes and a cash distribution of $21 million. During 2023, HG Re did not receive any distributions out of the Supplemental Trust.

HG Global Balance Sheets

The following tables present amounts for the HG Global segment that are presented within White Mountains’s consolidated balance sheet as of December 31, 2025 and 2024:

(1)The fair value of the BAM Surplus Notes includes accrued interest receivable.

(2)HG Global’s preferred dividends payable to White Mountains are eliminated in White Mountains’s consolidated financial statements. For segment reporting, these amounts are included within the HG Global segment and are eliminated against the offsetting receivables included within Other Operations.

Kudu

Kudu provides capital solutions for boutique asset and wealth managers for a variety of purposes, including generational ownership transfers, management buyouts, acquisition and growth finance and legacy partner liquidity. Kudu also provides strategic advice to managers from time to time.

Kudu deployed a total of $197 million, including transaction costs, into three new asset management firms in 2025. As of December 31, 2025, Kudu had deployed a total of $1.2 billion, including transaction costs, into 30 asset and wealth management firms globally, including three that have been exited. As of December 31, 2025, the asset and wealth management firms have combined assets under management (“AUM”) of approximately $153 billion, spanning a range of asset classes, including real estate, real assets, wealth management, hedge funds, private equity and alternative credit strategies. Since inception, Kudu’s capital was deployed at an initial average gross cash yield of 9.3% based on expected cash flows in the first year following deployment.

The following table presents the components of GAAP net income (loss), EBITDA and adjusted EBITDA included in the Kudu segment for the years ended December 31, 2025, 2024 and 2023:

(1) Net investment income includes revenues from Participation Contracts and income from short-term and other long-term investments.

(2) See“NON-GAAP FINANCIAL MEASURES” on page 85.

The following table presents the changes to the fair value of Kudu’s Participation Contracts for the years ended December 31, 2025 and 2024:

(1) As of December 31, 2025, 2024 and 2023, Kudu’s other long-term investments also include $6.4, $5.6 and $5.8 related to a private debt instrument.

(2) Includes $6.6 of non-cash contributions to (proceeds from) Participation Contracts for the year ended December 31, 2025.

(3) Includes $28.1 of proceeds receivable from Participation Contracts sold during the year ended December 31, 2024.

(4) Includes net realized and unrealized investment gains (losses) recognized from Participation Contracts beginning in the quarter a contract is classified as pending sale.

(5) Includes net unrealized investment gains (losses) recognized from (i) ongoing Participation Contracts and (ii) Participation Contracts prior to classification as pending sale.

Kudu Results — Year Ended December 31, 2025 versus Year Ended December 31, 2024

Kudu reported total revenues of $183 million, pre-tax income of $140 million and adjusted EBITDA of $65 million in 2025 compared to total revenues of $119 million, pre-tax income of $81 million and adjusted EBITDA of $55 million in 2024.

Total revenues, pre-tax income and adjusted EBITDA included $79 million of net investment income in 2025 compared to $67 million in 2024. The increase in net investment income was driven primarily by amounts earned from new deployments that Kudu made in 2024 and 2025. Total revenues and pre-tax income also included $104 million of net realized and unrealized investment gains in 2025 compared to $51 million in 2024. Net realized and unrealized investment gains in 2025 were driven by an increase in the fair value of Kudu’s Participation Contracts, primarily due to growth in assets under management at several managers and foreign currency exchange gains from a weakening U.S. dollar. Net realized and unrealized investment gains in 2024 were driven by an increase in the fair value of Kudu’s Participation Contracts, primarily due to growth in assets under management at several managers and lower discount rates across the portfolio, partially offset by foreign currency exchange losses resulting from a strengthening U.S. dollar and an unrealized loss from a publicly listed security received by Kudu in a prior sales transaction.

Kudu Results—Year Ended December 31, 2024 versus Year Ended December 31, 2023

Kudu reported total revenues of $119 million, pre-tax income of $81 million and adjusted EBITDA of $55 million in 2024 compared to total revenues of $177 million, pre-tax income of $137 million and adjusted EBITDA of $57 million in 2023.

Total revenues, pre-tax income and adjusted EBITDA included $67 million of net investment income in 2024 compared to $71 million in 2023. The decrease in net investment income was driven primarily by a $12 million realization of carried

interest for one of Kudu’s Participation Contracts in 2023, partially offset by amounts earned from new deployments that Kudu made during 2023 and 2024. Total revenues and pre-tax income also included $51 million of net realized and unrealized investment gains in 2024 compared to $106 million in 2023. Net realized and unrealized investment gains in 2024 were driven by an increase in the fair value of Kudu’s Participation Contracts, primarily due to growth in assets under management at several managers and lower discount rates across the portfolio, partially offset by foreign currency exchange losses resulting from a strengthening U.S. dollar and an unrealized loss from a publicly listed security received by Kudu in a prior sales transaction. Net realized and unrealized investment gains in 2023 were driven by an increase in the fair value of Kudu’s Participation Contracts, primarily due to a step-up in valuation related to a pending transaction, lower discount rates across the portfolio and growth in assets under management at several managers.

Bamboo

On January 2, 2024, White Mountains acquired a controlling interest in Bamboo.

On December 5, 2025, White Mountains completed the Bamboo Sale Transaction. As a result, White Mountains deconsolidated the Bamboo Group on December 5, 2025, and Bamboo is no longer a reportable segment. Through December 5, 2025, Bamboo’s results of operations are presented within the Bamboo segment. White Mountains’s noncontrolling equity interest in the Bamboo SPV is accounted for at fair value in other long-term investments within Other Operations. See Note 2 — “Significant Transactions”on page F-19.

Bamboo is a capital-light, tech- and data-enabled insurance distribution platform providing homeowners’ insurance and related products to the residential property market in California and, beginning in the third quarter of 2025, in Texas. Bamboo operates primarily through Bamboo MGA, its full-service MGA business, where the company manages all aspects of the placement process on behalf of its Capacity Providers, including product development, marketing, underwriting, policy issuance and claims oversight, and it earns commissions based on the volume and profitability of the insurance that it places.

The following table presents the components of GAAP net income (loss), MGA net income (loss), MGA EBITDA and MGA adjusted EBITDA included in White Mountains’s Bamboo segment for the period from January 1, 2025 to December 5, 2025 and for the year ended December 31, 2024:

Bamboo Results—Period ended December 5, 2025 versus Year Ended December 31, 2024

Bamboo reported commission and fee revenues of $211 million and pre-tax income of $40 million for the period from January 1, 2025 to December 5, 2025, while Bamboo reported commission and fee revenues of $135 million and pre-tax income of $33 million for the year ended December 31, 2024. Bamboo reported MGA pre-tax income of $41 million and MGA adjusted EBITDA of $91 million for the period from January 1, 2025 to December 5, 2025, while Bamboo reported MGA pre-tax income of $32 million and MGA adjusted EBITDA of $53 million for the year ended December 31, 2024.

Managed Premiums

Managed premiums represent the total premiums placed by Bamboo during the period. Managed premiums were $705 million for the period from January 1, 2025 to December 5, 2025 and $484 million for the year ended December 31, 2024. The increase in managed premiums was driven by growth in the renewal book as well as new business volume.

The following table presents Bamboo’s managed premiums for the years ended December 31, 2025, 2024 and 2023, which includes periods prior to White Mountains’s ownership of Bamboo and subsequent to the deconsolidation of Bamboo. White Mountains believes this information is useful in understanding the overall growth in Bamboo’s premium base.

(1) Total managed premiums were $705.2 for the period from January 1, 2025 to December 5, 2025, including $271.7 related to new

business and $433.5 related to net renewals, endorsements, reinstatements and cancellations.

On September 2, 2025, White Mountains acquired a controlling financial interest in Distinguished. White Mountains funded the Distinguished Transaction through a combination of cash on hand and new borrowings by Distinguished. White Mountains paid $225 million of cash consideration, including a post-closing purchase price adjustment of $1 million. In addition, Distinguished borrowed $50 million of incremental debt and utilized $7 million of cash on hand as part of the transaction. The consideration is subject to customary purchase price adjustments. At closing, White Mountains owned 55.5%, inclusive of its 1.7% previously-held interest, of Distinguished on a basic units outstanding basis (43.6% on a fully-diluted/ fully-converted basis, taking account of management’s equity incentives), while Distinguished management owned 4.2% of the basic units outstanding (24.7% on a fully-diluted/fully-converted basis). See Note 2 — “Significant Transactions”on page F-19.

Distinguished is a full-service MGA and program administrator for specialty property and casualty insurance. Distinguished places insurance across a diversified portfolio of programs broadly grouped into two verticals. The ScaleCo vertical consists of established programs, primarily focused on real estate and hospitality end markets. The GrowthCo vertical consists of start-up programs, focused on a diversified set of specialty property and casualty insurance products across multiple industries. On behalf of its insurance carrier partners, Distinguished typically manages all aspects of the placement process, including product development, marketing, underwriting and policy issuance. Distinguished earns commissions based on the volume and profitability of the insurance that it places. Distinguished does not retain insurance risk.

The following table presents the components of GAAP net income (loss), ScaleCo net income (loss), ScaleCo EBITDA and ScaleCo adjusted EBITDA included in White Mountains’s Distinguished segment for the period from September 2, 2025, the date of acquisition, through December 31, 2025:

Distinguished Results – Period from September 2, 2025 through December 31, 2025

Distinguished reported commission and fee revenues of $57 million, pre-tax loss of $17 million and ScaleCo adjusted EBITDA of $9 million for the period from September 2, 2025 through December 31, 2025.

Managed Premiums and Commission and Fee Revenues

Managed premiums, which represent the total premiums placed by Distinguished, were $188 million for the period from September 2, 2025 through December 31, 2025. The following table presents Distinguished’s managed premiums and commission and fee revenues by vertical for the period from September 2, 2025 through December 31, 2025.

For the year ended December 31, 2025, Distinguished’s total managed premiums were $568 million, which increased 6% compared to the year ended December 31, 2024. This includes periods prior to White Mountains’s ownership of Distinguished, which White Mountains believes is useful in understanding the overall size and growth in Distinguished’s premium base.

On December 5, 2025, White Mountains closed the Bamboo Sale Transaction. White Mountains received net cash proceeds at closing of $848 million and retained an indirect equity interest valued at $250 million. White Mountains’s indirect equity interest is held through the Bamboo SPV. White Mountains’s Other Operations recognized a net gain of $816 million, which was comprised of an $849 million net gain on sale of the Bamboo Group, partially offset by $33 million of parent company compensation costs recorded within general and administrative expenses. See Note 2 — “Significant Transactions”on page F-19.

The following table presents the components of pre-tax income (loss) included in White Mountains’s Other Operations for the years ended December 31, 2025, 2024 and 2023:

Other Operations Results—Year Ended December 31, 2025 versus Year Ended December 31, 2024

White Mountains’s Other Operations reported pre-tax income of $810 million in 2025 compared to $9 million in 2024. Results in 2025 were driven primarily by the Bamboo Sale Transaction, which resulted in a net gain of $816 million, including the impact of parent company compensation costs recorded within general and administrative expenses. White Mountains’s Other Operations reported unrealized investment gains from its investment in MediaAlpha of $30 million in 2025 compared to net realized and unrealized investment gains of $38 million in 2024. Excluding MediaAlpha, White Mountains’s Other Operations reported net realized and unrealized investment gains of $80 million in 2025 compared to $57 million in 2024. The increase in net realized and unrealized investment gains was driven primarily by higher gains from other long-term investments in 2025 compared to 2024. White Mountains’s Other Operations reported net investment income of $32 million in 2025 compared to $36 million in 2024. See “Summary of Investment Results” on page 74.

White Mountains’s Other Operations reported $201 million of other revenues in 2025 compared to $57 million in 2024. White Mountains’s Other Operations reported $152 million of cost of sales in 2025 compared to $30 million in 2024. The increases in other revenues and cost of sales were driven primarily by the acquisition of Enterprise Solutions by WTM Partners in 2025.

White Mountains’s Other Operations reported general and administrative expenses of $237 million in 2025 compared to $170 million in 2024. The increase in general and administrative expenses was driven primarily by higher incentive compensation costs, largely in connection with the Bamboo Sale Transaction, higher transaction costs and the consolidation of Enterprise Solutions. General and administrative expenses included $120 million of parent company compensation and benefits in 2025 compared to $92 million in 2024.

The Bamboo CRVs reported $5 million of pre-tax loss in 2025 compared to $9 million of pre-tax income in 2024. The Bamboo CRVs’ results included earned premiums of $22 million, loss and LAE of $20 million and acquisition expenses of $8 million in 2025 compared to earned premiums of $33 million, loss and LAE of $12 million and acquisition expenses of $12 million in 2024. Loss and LAE in 2025 included approximately $12 million related to the January 2025 California wildfires.

Share Repurchases

In the year ended December 31, 2025, White Mountains repurchased and retired 100,581 of its common shares for $203 million at an average share price of $2,013.67, or 92% of White Mountains’s book value per share as of December 31, 2025. This included 64,064 shares repurchased through the self-tender offer in December.

Other Operations Results—Year Ended December 31, 2024 versus Year Ended December 31, 2023

White Mountains’s Other Operations reported pre-tax income of $9 million in 2024 compared to $113 million in 2023. White Mountains’s Other Operations reported net realized and unrealized investment gains from its investment in MediaAlpha of $38 million in 2024 compared to unrealized investment gains of $27 million in 2023. Excluding MediaAlpha, White Mountains’s Other Operations reported net realized and unrealized investment gains of $57 million in 2024 compared to $189 million in 2023. The decrease in net realized and unrealized investment gains was driven primarily by lower unrealized gains from other long-term investments in 2024 compared to 2023. White Mountains’s Other Operations reported net investment income of $36 million in 2024 compared to $30 million in 2023. See “Summary of Investment Results” on page 74.

White Mountains’s Other Operations reported $57 million of other revenues in 2024 compared to $81 million in 2023. White Mountains’s Other Operations reported $30 million of cost of sales in 2024 compared to $40 million in 2023. The decreases in other revenues and cost of sales were driven primarily by a business sold within Other Operations in 2023.

White Mountains’s Other Operations reported general and administrative expenses of $170 million in 2024 compared to $182 million in 2023. General and administrative expenses included $92 million of parent company compensation and benefits in 2024 compared to $94 million in 2023.

White Mountains’s Other Operations reported $9 million of pre-tax income in 2024 related to the Bamboo CRV that incepted on April 1, 2024. The Bamboo CRV’s results included earned premiums of $33 million, loss and LAE of $12 million and acquisition expenses of $12 million.

Share Repurchases

In the year ended December 31, 2024, White Mountains repurchased and retired 5,269 of its common shares for $8 million at an average share price of $1,505.01.

II. Summary of Investment Results

White Mountains’s total investment results include results from all segments. For purposes of discussing rates of return, percentages are presented gross of management fees and trading expenses.

Effective December 5, 2025, White Mountains no longer consolidates Bamboo. Through December 5, 2025, White Mountains’s consolidated financial statements included Bamboo’s investment results. Effective July 1, 2024, White Mountains no longer consolidates BAM. Through June 30, 2024, White Mountains’s consolidated financial statements included BAM’s investment results. See Note 2 — “Significant Transactions”on page F-19.

Gross Investment Returns and Benchmark Returns

The following table presents the pre-tax time-weighted investment returns for White Mountains’s consolidated portfolio for the years ended December 31, 2025, 2024 and 2023:

Investment Returns—Year Ended December 31, 2025 versus Year Ended December 31, 2024

White Mountains’s total consolidated portfolio return on invested assets was 9.1% in 2025, which included $30 million of unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the total consolidated portfolio return on invested assets was 8.9% in 2025. Excluding MediaAlpha, investment returns in 2025 were driven primarily by net investment income and net unrealized investment gains from other long-term investments, net investment income from the fixed income portfolio and net realized gains from common equity securities.

White Mountains’s total consolidated portfolio return on invested assets was 6.9% in 2024, which included $38 million of

net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the

total consolidated portfolio return on invested assets was 6.5% in 2024. Excluding MediaAlpha, investment returns in 2024

were driven primarily by net investment income and net realized and unrealized investment gains from other long-term investments, net investment income from the fixed income portfolio and net unrealized gains from common equity securities.

Fixed Income Results

White Mountains’s fixed income portfolio, including short-term investments, totaled $4.7 billion and $3.5 billion as of December 31, 2025 and 2024, which represented 56% and 54% of total invested assets. The duration of White Mountains’s fixed income portfolio, including short-term investments, was 1.5 years and 1.9 years as of December 31, 2025 and 2024. The change in the fair value and duration was driven primarily by cash inflows into the fixed income portfolio, principally related to the proceeds from the Bamboo Sale Transaction. White Mountains’s fixed income portfolio includes fixed maturity and short-term investments held on deposit or as collateral. See Note 3 — “Investment Securities” on page F-23.

White Mountains’s fixed income portfolio returned 5.9% in 2025 compared to 4.3% in 2024, underperforming and outperforming the Bloomberg U.S. Intermediate Aggregate Index returns of 7.5% and 2.5% for the comparable periods. Results in 2025 were driven primarily by net investment income and White Mountains’s short duration positioning as interest rates declined in the period. Results in 2024 were driven primarily by net investment income.

Common Equity Securities, Investment in MediaAlpha and Other Long-Term Investments Results

White Mountains’s portfolio of common equity securities, its investment in MediaAlpha and other long-term investments totaled $3.7 billion and $3.0 billion as of December 31, 2025 and 2024, which represented 44% and 46% of total invested assets. The change was driven primarily by increased exposure to other long-term investments, principally due to investments in new unconsolidated equities and an increase in the fair value of Kudu’s Participation Contracts. See Note 3 — “Investment Securities” on page F-23.

White Mountains’s portfolio of common equity securities, its investment in MediaAlpha and other long-term investments returned 13.1% in 2025, which included $30 million of unrealized investment gains from White Mountains’s investment in MediaAlpha. White Mountains’s portfolio of common equity securities and other long-term investments returned 13.0% in 2025. White Mountains’s portfolio of common equity securities, its investment in MediaAlpha and other long-term investments returned 10.0% in 2024, which included $38 million of net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha. White Mountains’s portfolio of common equity securities and other long-term investments returned 9.4% in 2024.

White Mountains’s portfolio of common equity securities generally consists of international listed equity funds, primarily held at Ark, and passive ETFs. White Mountains’s ETFs seek to provide investment results generally corresponding to the performance of the S&P 500 Index. White Mountains’s portfolio of common equity securities was $483 million and $650 million as of December 31, 2025 and 2024. The decrease in common equity securities in 2025 was due to the sale of White Mountains’s ETF portfolio in the first half of 2025 to fund planned capital deployments. See Note 2 — “Significant Transactions”on page F-19. Subsequent to the Bamboo Sale Transaction, White Mountains began to reestablish its ETF portfolio.

White Mountains’s portfolio of common equity securities returned 10.6% in 2025 compared to 11.3% in 2024, underperforming the S&P 500 Index returns of 17.9% and 25.0% for the comparable periods. The underperformance in each period was driven primarily by certain international listed equity funds that employ a market neutral strategy. In 2025, the underperformance was also attributable to the sale of White Mountains’s ETF portfolio in the first half of the year.

White Mountains maintains a portfolio of other long-term investments that consists primarily of unconsolidated entities, including Kudu’s Participation Contracts, the Bamboo SPV, PassportCard/DavidShield and the BroadStreet SPV, as well as private equity funds and hedge funds, a bank loan fund and Lloyd’s trust deposits. White Mountains’s portfolio of other long-term investments totaled $3.0 billion and $2.2 billion as of December 31, 2025 and 2024.

White Mountains’s portfolio of other long-term investments returned 13.2% in 2025 compared to 8.9% in 2024. Returns for 2025 were driven primarily by net investment income and net realized and unrealized investment gains from Kudu’s Participation Contracts, as well as net investment income and net realized and unrealized investment gains from certain unconsolidated entities, private equity funds and hedge funds. Returns for 2024 were driven primarily by net investment income and net realized and unrealized investment gains from Kudu’s Participation Contracts, as well as net unrealized investment gains from a bank loan fund and ILS funds.

Investment Returns—Year Ended December 31, 2024 versus Year Ended December 31, 2023

White Mountains’s total consolidated portfolio return on invested assets was 6.9% in 2024, which included $38 million of net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the total consolidated portfolio return on invested assets was 6.5% in 2024. Excluding MediaAlpha, investment returns in 2024 were driven primarily by net investment income and net unrealized investment gains from other long-term investments, net investment income from the fixed income portfolio and net unrealized gains from common equity securities.

White Mountains’s total consolidated portfolio return on invested assets, both including and excluding White Mountains’s investment in MediaAlpha, was 11.4% in 2023. The total consolidated portfolio return included $27 million of unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, investment returns in 2023 were driven primarily by net investment income and net realized and unrealized investment gains from the other long-term investments and fixed income portfolios.

Fixed Income Results

White Mountains’s fixed income portfolio, including short-term investments, totaled $3.5 billion and $3.6 billion as of December 31, 2024 and 2023, which represented 54% and 56% of total invested assets. The duration of White Mountains’s fixed income portfolio, including short-term investments, was 1.9 years as of both December 31, 2024 and 2023. White Mountains’s fixed income portfolio includes fixed maturity and short-term investments held on deposit or as collateral. See Note 3 — “Investment Securities” on page F-23.

White Mountains’s fixed income portfolio returned 4.3% in 2024 compared to 5.8% in 2023, outperforming the Bloomberg U.S. Intermediate Aggregate Index returns of 2.5% and 5.2% for the comparable periods. Results in 2024 were driven primarily by net investment income. Results in 2023 were driven primarily by net investment income and net unrealized investment gains as shorter-term interest rates declined marginally in the period.

Common Equity Securities, Investment in MediaAlpha and Other Long-Term Investments Results

White Mountains’s portfolio of common equity securities, its investment in MediaAlpha and other long-term investments totaled $3.0 billion and $2.8 billion as of December 31, 2024 and 2023, which represented 46% and 44% of total invested assets. See Note 3 — “Investment Securities” on page F-23.

White Mountains’s portfolio of common equity securities, its investment in MediaAlpha and other long-term investments returned 10.0% in 2024, which included $38 million of net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha. White Mountains’s portfolio of common equity securities and other long-term investments returned 9.4% in 2024. White Mountains’s portfolio of common equity securities, its investment in MediaAlpha and other long-term investments returned 18.5% in 2023, which included $27 million of unrealized investment gains from White Mountains’s investment in MediaAlpha. White Mountains’s portfolio of common equity securities and other long-term investments returned 19.0% in 2023.

White Mountains’s portfolio of common equity securities was $650 million and $538 million as of December 31, 2024 and 2023. White Mountains’s portfolio of common equity securities returned 11.3% in 2024 compared to 13.4% in 2023, underperforming the S&P 500 Index returns of 25.0% and 26.3% for the comparable periods. The underperformance in 2024 and 2023 was driven primarily by certain international listed equity funds that employ a market neutral strategy.

White Mountains’s portfolio of other long-term investments totaled $2.2 billion and $2.0 billion as of December 31, 2024 and 2023. White Mountains’s portfolio of other long-term investments returned 8.9% in 2024 compared to 20.6% in 2023. Returns for 2024 were driven primarily by net investment income and net realized and unrealized investment gains from Kudu’s Participation Contracts, as well as net unrealized investment gains from a bank loan fund and ILS funds. Returns for 2023 were driven primarily by net investment income and net realized and unrealized investment gains from Kudu’s Participation Contracts, net realized and unrealized investment gains from private equity funds, hedge funds and unconsolidated entities, as well as net investment income and unrealized gains from ILS funds.

Portfolio Composition

The following table presents the composition of White Mountains’s total investment portfolio as of December 31, 2025 and 2024:

The following table presents the breakdown of White Mountains’s fixed maturity investments as of December 31, 2025 and 2024 by credit class, based upon issuer credit ratings provided by Standard & Poor’s, or if unrated by Standard & Poor’s, long-term obligation ratings provided by Moody’s:

(1)Includes mortgage-backed securities, which carry the full faith and credit guarantee of the U.S. government (i.e., GNMA) or are guaranteed by a government sponsored entity (i.e., FNMA, FHLMC).

(1)Includes mortgage-backed securities, which carry the full faith and credit guarantee of the U.S. government (i.e., GNMA) or are guaranteed by a government sponsored entity (i.e., FNMA, FHLMC).

The following table presents the cost or amortized cost and carrying value of White Mountains’s fixed maturity investments by contractual maturity as of December 31, 2025 and 2024. Actual maturities could differ from contractual maturities because borrowers may have the right to call or prepay certain obligations with or without call or prepayment penalties.

The following table presents the composition of White Mountains’s other long-term investments portfolio as of December 31, 2025 and 2024:

Foreign Currency Exposure

As of December 31, 2025, White Mountains had foreign currency exposure on $376 million of net assets, primarily related to Ark/WM Outrigger’s non-U.S. contracts, Kudu’s non-U.S. Participation Contracts and a private debt instrument, as well as certain other foreign consolidated and unconsolidated entities.

The following table presents the fair value of White Mountains’s foreign denominated net assets (liabilities) by segment as of December 31, 2025:

III. Income Taxes

As of December 31, 2025, the primary jurisdictions in which the Company’s subsidiaries and branches operated and were subject to tax are Israel, Luxembourg, the United Kingdom and the United States.

On December 15, 2022, European Union Member States voted to adopt the EU Minimum Tax Directive in conformity with the OECD Pillar Two initiative. The Pillar Two initiative includes a set of model rules that are generally designed to impose a top-up tax on a large multinational enterprise group to the extent that the group is not subject to an effective tax rate of at least 15% in each jurisdiction in which the group has a consolidated affiliate or permanent establishment. The EU Minimum Tax Directive required European Union Member States to enact conforming law by December 31, 2023. The main rule of the EU Minimum Tax Directive, the IIR, was to become effective for fiscal years beginning on or after December 31, 2023, while the UTPR was to become effective for fiscal years beginning on or after December 31, 2024. The EU Minimum Tax Directive also permits European Union Member States to elect to apply a QDMTT for fiscal years beginning on or after December 31, 2023.

On July 11, 2023, the United Kingdom enacted conforming Pillar Two legislation including the IIR and QDMTT, which became effective for fiscal years beginning on or after December 31, 2023. On March 20, 2025, the United Kingdom enacted legislation adopting the Pillar Two UTPR effective for fiscal years beginning on or after December 31, 2024. Under the legislation, the effective date of the UTPR is deferred until fiscal years beginning on or after December 31, 2029 for U.K. companies in consolidated groups that meet certain requirements. To qualify for the deferral, generally the group must (i) have consolidated affiliates and permanent establishments in six or fewer countries and (ii) have no more than €50 million of net tangible assets outside of the country where the group has the largest amount of net tangible assets. White Mountains expects to meet the requirements to be exempt from the U.K. UTPR until January 1, 2030.

On December 20, 2023, Luxembourg enacted conforming Pillar Two legislation including the IIR and QDMTT, which became effective for fiscal years beginning on or after December 31, 2023, and the UTPR, which became effective for fiscal years beginning on or after December 31, 2024. The Luxembourg Pillar Two legislation defers the effective date of the QDMTT and UTPR until fiscal years beginning on or after December 31, 2028 and 2029, respectively, for Luxembourg companies in consolidated groups that meet certain requirements. To qualify for the deferral, generally the group must (i) have consolidated affiliates and permanent establishments in six or fewer countries and (ii) have no more than €50 million of net tangible assets outside of the country where the group has the largest amount of net tangible assets. White Mountains expects to meet the requirements to be exempt from the Luxembourg QDMTT and UTPR until January 1, 2029 and 2030, respectively.

On December 27, 2023, Bermuda enacted a 15% corporate income tax that became effective on January 1, 2025. The Bermuda legislation defers the effective date for five years for Bermuda companies in consolidated groups that meet certain requirements. To qualify for the deferral, generally the group must (i) have consolidated affiliates and permanent establishments in six or fewer countries, (ii) have no more than €50 million of net tangible assets outside of the country where the group has the largest amount of net tangible assets and (iii) not have a consolidated Bermuda affiliate or Bermuda permanent establishment directly or indirectly owned by a parent entity that is subject to the Pillar Two IIR in any jurisdiction. White Mountains expects to meet the requirements to be exempt from the Bermuda corporate income tax until January 1, 2030.

The Bermuda legislation also provides for an optional economic transition adjustment that can decrease or increase future years’ taxable income. Under GAAP, this economic transition adjustment was required to be recorded as a deferred tax asset or liability as of December 31, 2023 if a company intended to apply the adjustment to compute its taxable income. Accordingly, White Mountains recognized a net deferred tax benefit of $68 million in 2023, of which $51 million was recognized at Ark and $17 million was recognized at HG Global. As of July 1, 2024, White Mountains no longer consolidates BAM. As a result of the deconsolidation, the BAM Surplus Notes are recorded at fair value, which resulted in the reversal of a $5 million deferred tax liability related to the economic transition adjustment, generating a $5 million deferred tax benefit in 2024. On December 11, 2025, Bermuda enacted legislation that changed the scope of assets and liabilities subject to the economic transition adjustment. This legislation resulted in the reversal of a $5 million deferred tax liability related to the economic transition adjustment, generating a $5 million deferred tax benefit in 2025.

On January 15, 2025, the OECD released administrative guidance on its Pillar Two model rules. The January 2025 OECD Administrative Guidance provides that, subject to limited exceptions, deferred tax expense attributable to deferred tax assets resulting from the introduction of a new corporate income tax after November 30, 2021 is to be excluded when assessing whether a multinational enterprise group has an effective tax rate of at least 15% in the jurisdiction that adopted the corporate income tax. Deferred tax assets associated with the economic transition adjustment recorded under the Bermuda corporate income tax are expected to be within the scope of the January 2025 OECD Administrative Guidance.

On December 17, 2025, Luxembourg enacted legislation that adopts the January 2025 OECD Administrative Guidance. Accordingly, in any future year in which the economic transition adjustment deferred tax asset is utilized, White Mountains expects to incur a top-up tax under the Luxembourg UTPR equal to the amount of the deferred tax expense for that year associated with the economic transition adjustment. Consequently, White Mountains expects to derive no economic benefit from the Bermuda economic transition adjustment and intends to opt out of the economic transition adjustment upon becoming subject to Bermuda corporate income tax. Accordingly, White Mountains recognized a deferred tax expense of $78 million in 2025 to reverse the net deferred tax asset related to the Bermuda economic transition adjustment.

On December 11, 2025, the Bermuda government enacted legislation providing certain incentives for Bermuda-based employment, training, local expenditure and community development. The incentives are based on qualifying expenditures of eligible Bermuda entities and are provided in the form of a refundable tax credit. A Bermuda entity may be eligible for the incentives regardless of whether it is subject to the Bermuda corporate income tax. For the year ended December 31, 2025, White Mountains accrued a $10 million benefit for the incentives as a reduction to general and administrative expenses.

On July 4, 2025, the U.S. enacted the OBBBA. White Mountains does not expect the OBBBA to have a material impact on its financial statements.

White Mountains reported income tax expense of $127 million in 2025 on pre-tax income of $1,329 million. The difference between White Mountains’s effective tax rate and the current U.S. statutory rate of 21% was driven primarily by income generated in jurisdictions with lower tax rates than the United States, income attributable to certain gains not subject to tax in Luxembourg, a full valuation allowance on net deferred tax assets in certain U.S. operations (consisting of Other Operations), withholding taxes and state income taxes. The effective rate also differed from the U.S. statutory rate of 21% due to the $73 million net deferred tax expense related to the reversal of the Bermuda economic transition adjustment.

White Mountains reported income tax expense of $33 million in 2024 on pre-tax income of $317 million. The difference between White Mountains’s effective tax rate and the current U.S. statutory rate of 21% was driven primarily by income generated in jurisdictions with lower tax rates than the United States, a full valuation allowance on net deferred tax assets in certain U.S. operations (consisting of Other Operations and BAM), withholding taxes and state income taxes.

White Mountains reported income tax benefit of $16 million in 2023 on pre-tax income of $565 million. The difference between White Mountains’s effective tax rate and the current U.S. statutory rate of 21% was driven primarily by income generated in jurisdictions with lower tax rates than the United States, a full valuation allowance on net deferred tax assets in certain U.S. operations (consisting of Other Operations and BAM), withholding taxes and state income taxes. The effective rate also differed from the U.S. statutory rate of 21% due to the $68 million deferred tax benefit related to the Bermuda economic transition adjustment.