WHITE MOUNTAINS INSURANCE GROUP LTD

SELECTED FINANCIAL DATA

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

(2)Total net capital drawn represents equity and debt capital drawn and invested less cumulative distributions.

(3)Return on equity is calculated based on the GAAP net income (loss) divided by the average of Kudu’s beginning and ending GAAP equity.

(1) As of June 30, 2025, December 31, 2025 and 2024, Kudu’s other long-term investments also include $6.1, $6.4 and $5.6 related to a private debt instrument.

(2)Includes contributions to new and existing participation contracts.

(3)Includes $3.5 of non-cash contributions to (proceeds from) participation contracts for the nine months ended September 30, 2026.

(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.

(6) As of September 30, 2025, Kudu’s other long-term investments also include $6.2 related to a private debt instrument.

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

(1) Includes results for periods subsequent to the acquisitions of Enterprise Solutions on April 1, 2025, Basesix on April 1, 2026 and Hawkeye Electric on May 1, 2026.

Regulation G

This earnings release includes non-GAAP financial measures that have been reconciled from their most comparable GAAP financial measures.

•Ark’s tangible book value and growth in tangible book value are non-GAAP financial measures.

Tangible book value is a non-GAAP financial measure derived by adjusting GAAP book value to exclude (i) goodwill and other intangible assets, (ii) the deferred tax liability on other intangible assets and (iii) the contingent consideration liability. The contingent consideration liability represents the estimated fair value of the additional shares that could be earned by management rollover shareholders if and to the extent that White Mountains achieves certain multiple of invested capital return thresholds. If earned, these additional shares would result in a reallocation of economics among Ark’s shareholders, which is reflected in the fair value of the contingent consideration liability recorded by White Mountains, but would have no impact on Ark’s stand-alone book value or tangible book value.

Growth in tangible book value equals the change in tangible book value plus dividends for the period divided by beginning tangible book value.

White Mountains believes that these non-GAAP financial measures are useful to management and investors in evaluating Ark’s enterprise value.

The following table presents the reconciliation of Ark’s GAAP book value to tangible book value.

(1) Amounts are net of deferred tax liabilities related to other intangible assets of $43.9.

•Kudu’s EBITDA, adjusted EBITDA, annualized adjusted EBITDA, annualized revenue and cash revenue yield are non-GAAP financial measures.

EBITDA is a non-GAAP financial measure that adds back interest expense on debt, income tax (expense) benefit, depreciation and amortization of other intangible assets to GAAP net income (loss).

Adjusted EBITDA is a non-GAAP financial measure that excludes certain other items in GAAP net income (loss) in addition to those added back to calculate EBITDA. The items relate to (i) net realized and unrealized investment gains (losses) on Kudu’s revenue and earnings participation contracts, (ii) non-cash equity-based compensation expense and (iii) transaction expenses. A description of each item follows:

•Net realized and unrealized investment gains (losses) - Represents net unrealized investment gains and losses recorded on Kudu’s revenue and earnings participation contracts, which are recorded at fair value under GAAP, and realized investment gains and losses from participation contracts sold during the period.

•Non-cash equity-based compensation expense - Represents non-cash expenses related to Kudu’s management compensation that are settled with equity units in Kudu.

•Transaction expenses - Represents costs directly related to Kudu’s mergers and acquisitions activity, such as external lawyer, banker, consulting and placement agent fees, which are not capitalized and are expensed under GAAP.

Annualized adjusted EBITDA is a non-GAAP financial measure that (i) annualizes partial year revenues related to Kudu’s revenue and earnings participation contracts acquired during the previous 12-month period and (ii) removes partial year revenues related to revenue and earnings participation contracts sold during the previous 12-month period.

Annualized revenue is a non-GAAP financial measure that adds the adjustments for annualized adjusted EBITDA to GAAP net investment income.

Cash revenue yield is a non-GAAP financial measure that is derived using annualized revenue as a percentage of total net capital drawn and invested. The most directly comparable GAAP financial measure is net investment income revenue yield, which is derived using GAAP net investment income as a percentage of total net capital drawn and invested.

White Mountains believes that these non-GAAP financial measures are useful to management and investors in evaluating Kudu’s underlying performance. White Mountains also believes that annualized adjusted EBITDA is useful to management and investors in understanding the full earnings profile of Kudu’s business as of the end of any 12-month period. See page 18 for the reconciliation of Kudu’s GAAP net income (loss) to EBITDA, adjusted EBITDA and annualized adjusted EBITDA, and the reconciliation of Kudu’s GAAP net investment income to annualized revenue.

•Distinguished’s ScaleCo net income (loss), ScaleCo EBITDA and ScaleCo adjusted EBITDA are non-GAAP financial measures.

ScaleCo net income (loss) is a non-GAAP financial measure that excludes the results of the GrowthCo vertical, which is consolidated under GAAP, from Distinguished’s consolidated GAAP net income (loss).

ScaleCo EBITDA is a non-GAAP financial measure that adds back interest expense on debt, income tax (expense) benefit, depreciation and amortization of other intangible assets to ScaleCo net income (loss).

ScaleCo adjusted EBITDA is a non-GAAP financial measure that excludes certain other items in GAAP net income (loss) in addition to those items added back to calculate ScaleCo EBITDA. The items relate to (i) non-cash equity-based compensation expense, (ii) restructuring expenses, (iii) transaction expenses, (iv) software impairment and (v) legal settlement expenses. A description of each item follows:

•Non-cash equity-based compensation expense - Represents non-cash expenses related to Distinguished’s management compensation that are settled with equity units in Distinguished.

•Restructuring expenses - Represents costs related to Distinguished’s corporate restructuring and capital planning activities.

•Transaction expenses -Represents costs directly related to transaction activities at Distinguished, which are not capitalized and are expensed under GAAP.

•Software impairment - Represents expense related to Distinguished’s write-off of capitalized software that is no longer in use.

•Legal settlement expenses- Represents amounts incurred related to legal settlements.

White Mountains believes that these non-GAAP financial measures are useful to management and investors in evaluating Distinguished’s underlying performance. White Mountains also believes that excluding the results of the GrowthCo vertical, which Distinguished views as an investment in start-up programs, is useful to understanding the underlying performance of Distinguished’s established programs. See page 21 for the reconciliation of Distinguished’s consolidated GAAP net income (loss) to ScaleCo net income (loss), ScaleCo EBITDA and ScaleCo adjusted EBITDA.

•WTM Partners’s EBITDA and adjusted EBITDA are non-GAAP financial measures. EBITDA is a non-GAAP financial measure that adds back interest expense on debt, income tax (expense) benefit, depreciation and amortization of other intangible assets to GAAP net income (loss). Adjusted EBITDA is a non-GAAP financial measure that excludes certain other items in GAAP net income (loss) in addition to those added back to calculate EBITDA. The items relate to (i) transaction expenses and (ii) restructuring and integration expenses. A description of each item follows:

•Transaction expenses - Represents costs directly related to WTM Partners’s mergers and acquisitions activity, such as external lawyer, banker, consulting and placement agent fees, which are not capitalized and are expensed under GAAP.

•Restructuring and integration expenses - Represents costs related to WTM Partners’s corporate restructuring and mergers and acquisitions integration activities.

White Mountains believes that these non-GAAP financial measures are useful to management and investors in evaluating WTM Partners’s underlying performance. See page 22 for the reconciliation of WTM Partners’s GAAP net income (loss) to EBITDA and adjusted EBITDA.

•Total consolidated portfolio return excluding MediaAlpha and total equity portfolio return excluding MediaAlpha are non-GAAP financial measures that remove the net investment income and net realized and unrealized investment gains (losses) from White Mountains’s investment in MediaAlpha. White Mountains believes these measures to be useful to management and investors by showing the underlying performance of White Mountains’s investment portfolio and equity portfolio without regard to White Mountains’s investment in MediaAlpha. The following tables present reconciliations from GAAP to the reported percentages: