A benign catastrophe season and continued improvement in underwriting margins at majority-owned OneBeacon OB led to a 3% sequential increase in adjusted book value to $606 per share at White Mountains Insurance Group WTM . In comparison with last year’s first quarter, the combined ratio (expense divided by earned premiums) fell to 81% from 84% at Sirius Group, White Mountains’ reinsurance subsidiary, while OneBeacon also … Continue reading White Mountains’ Underwriting Margins Drive 1Q Book Value Increase