White Mountains Insurance Group Ltd has reported third-quarter net income attributable to common shareholders of $114 million, or $44.18 per share, down from $179 million, or $69.68 per share, in the same quarter last year.

Book value per share rose 3 per cent during the quarter to $1,851, a 6 per cent increase year-to-date including dividends. Manning Rountree, chief executive, said the quarter reflected “good operating results and investment returns”, pointing to strong contributions from the company’s reinsurance arm, Ark; financial guarantor, HG Global; and asset management unit, Kudu.

White Mountains’ comprehensive income for the quarter was $114 million, compared to $180 million a year earlier. Total revenues increased to $864 million, up from $839 million in Q3 2024.

Among subsidiaries, Ark posted a 76 per cent combined ratio and $97 million in pre-tax income, supported by minimal catastrophe losses. Gross written premiums were $366 million in the quarter and $2.3 billion year-to-date, up 18 per cent from last year.

HG Global rebounded with $22 million in pre-tax income, versus a $63 million loss a year ago, and 24 per cent growth in par value of policies assumed.

Kudu delivered $44 million in pre-tax income and a 9 per cent trailing twelve-month return on equity, reflecting gains from new investment participation contracts.

Bamboo, which White Mountains agreed in October to sell a 77 per cent stake in to CVC Capital Partners, reported record results with $15 million in pre-tax income and a 58 per cent year-over-year rise in managed premiums. The sale is expected to add about $325 per share to White Mountains’ book value in the fourth quarter, bringing it to an estimated $2,176 per share.

The group also closed its $224 million acquisition of Distinguished, a speciality managing general agent and programme administrator, on September 2.

White Mountains’ total investment portfolio returned 2.1 per cent in the quarter, or 2.0 per cent excluding its stake in MediaAlpha, where unrealised gains totalled $8 million.

Mr Rountree noted that after the Bamboo sale closes, the company’s undeployed capital will rise from $0.3 billion to $1.1 billion, positioning it for further investments.