White Mountains Insurance Group, Ltd. filed an earnings press release on November 5, 2026, reporting third-quarter and first-nine-months 2026 results, including a 1% decrease in book value per share to $2,243 as of September 30, 2026.

Key Highlights

  • Book value per share: $2,243 as of September 30, 2026, down 1% for the third quarter and up 3% for the first nine months of 2026, including dividends.
  • MediaAlpha impact: MediaAlpha's share price declined 24% in the third quarter, producing $54 million of mark-to-market losses on White Mountains's remaining position, according to the filing.
  • Ark combined ratio: Ark reported a combined ratio of 75% in the third quarter and 83% in the first nine months of 2026, each one point better than the comparable prior-year periods.
  • Ark gross written premiums: $386 million in the third quarter and $2,254 million in the first nine months of 2026.
  • HG Global record quarter: HG Global generated gross written premiums of $19 million in the third quarter of 2026, described by the company as a record.
  • Comprehensive income (loss): Comprehensive loss attributable to common shareholders was $(39) million in the third quarter of 2026, compared to $114 million in the third quarter of 2025.
  • Undeployed capital: The CEO stated that undeployed capital remains at "roughly $0.8 billion."

White Mountains Reports Mixed Q3 2026 Results Across Business Segments

White Mountains Insurance Group, Ltd. (NYSE:WTM) disclosed third-quarter 2026 results showing a 1% decline in book value per share to $2,243, while the first-nine-months figure remained up 3%, including dividends. According to the filing, higher interest rates and a lower MediaAlpha share price drove unrealized investment losses during the quarter. Net realized and unrealized investment losses were $(69) million in the third quarter of 2026 versus gains of $76 million in the third quarter of 2025. Losses attributable to the company's MediaAlpha position were $(54) million in the third quarter of 2026, compared to gains of $8 million in the same period of 2025.

Ark, the company's (re)insurance segment, reported a combined ratio of 75% for the quarter and 83% year to date, both one point better than the prior-year periods, the filing stated. Ark's results included two points of catastrophe losses in the third quarter of 2026, driven primarily by losses related to the war in Iran. Ark recorded estimated losses of $10 million in the third quarter and $52 million in the first nine months of 2026 related to that war, net of reinsurance and reinstatement premiums. Ark's pre-tax income was $64 million in the third quarter of 2026, down from $97 million in the third quarter of 2025, with the difference attributed in part to net realized and unrealized investment losses of $(40) million versus gains of $18 million in the year-ago quarter.

Kudu reported adjusted EBITDA of $18 million in the third quarter of 2026, up from $15 million in the same period of 2025, though its trailing 12-month return on equity declined to 8% as of September 30, 2026, from 15% as of June 30, 2026, primarily due to lower unrealized investment gains, the filing disclosed. HG Global reported gross written premiums of $19 million in the third quarter, up from $16 million a year earlier, with total par value of policies assumed reaching $929 million for the quarter.

What Was Disclosed

White Mountains reported Q3 and first-nine-months 2026 financial results for its insurance and investment segments, covering book value per share, comprehensive income, Ark's underwriting metrics and premiums, Kudu's revenues and adjusted EBITDA, and HG Global's gross written premiums and par value figures.