Bermuda-based White Mountains Insurance Group Ltd made a net loss of $28 million in the first quarter as its reinsurance segment took a $125 million hit from catastrophe losses.However the group, which includes OneBeacon, White Mountains Re and Esurance, was able to announce a 1.6 percent increase in adjusted book value to $447 per share during the quarter, including dividends.Ray Barrette, chairman and CEO, commented: “It was a good quarter, as we grew adjusted book value despite big earthquakes in Japan and New Zealand. White Mountains Re’s combined ratio was 132 percent, driven by catastrophe losses.“However, the much weaker US dollar boosted results, offsetting a good part of those losses. OneBeacon posted a strong 3.5 percent growth in book value per share and a 94 percent combined ratio.“Esurance’s adjusted combined ratio improved to 102 percent and premiums grew six percent on strong new policy sales at both Esurance and Answer Financial. Investment returns were good. We bought back almost 250,000 shares in the quarter, adding about $3 to adjusted book value per share.”OneBeacon’s combined ratio for the quarter was 94 percent compared to 112 percent for the first quarter of last year.Catastrophe losses added three points to the combined ratio in the first quarter of 2011 compared to 10 points in the first quarter of last year.The first quarter of 2011 included two points of favourable loss reserve development compared to one point for the first quarter of last year. The expense ratio increased by one point compared to the first quarter of last year.Mike Miller, CEO of OneBeacon, said: “During the quarter, we announced and have since completed a cash tender offer for $150 million of our outstanding senior notes, further reducing our debt to capital. Our balance sheet remains in great shape.”Net written premiums were $278 million in the first quarter of 2011, a decrease of 25 percent from the same period last year, reflecting the sale of the personal lines business.White Mountains Re’s combined ratio for the first quarter of both 2011 and 2010 was 132 percent, as both periods were significantly impacted by catastrophe losses.Major losses in the first quarter included $80 million related to the Japan earthquake and tsunami, $42 million from the February New Zealand earthquake and $3 million related to floods and cyclone Yasi in Australia.Catastrophe losses in the first quarter of 2010 were principally from the Chilean earthquake and European windstorm Xynthia. The first quarter of 2011 also included five points of favourable loss reserve development compared to three points for the first quarter of last year.White Mountains Re’s recorded property losses from the earthquake and tsunami in Japan are currently estimated principally using third party and internal catastrophe models, applying overall estimates of industry insured losses to White Mountains Re’s exposure information.The modelled portion of the property loss estimate is based upon an industry loss event of $35 billion, currently the upper end of the AIR and RMS estimates of insured losses.The overall loss estimate also includes estimated losses for marine, accident and health, aviation and contingency lines. Catastrophe exposure modeling and loss estimation is inherently uncertain, and as claims are reported and settled, White Mountains Re’s estimates could change, maybe materially.Allan Waters, CEO of White Mountains Re, said, “While the extent of the devastation in Japan makes our initial loss estimate particularly difficult to pin down at this point, the impact will remain manageable under any foreseeable scenario.“We were intentionally underweighted in Japan, New Zealand and Australia. We continue to be strongly capitalised and well positioned to take advantage of underwriting opportunities in the market.”Gross written premiums were down four percent for the first quarter of 2011, while net written premiums were down one percent. These decreases were primarily due to property lines, where ceding companies are reducing their writings and restructuring programs to retain more net exposure.Esurance’s adjusted combined ratio was 102 percent for the first quarter of 2011 compared to 106 percent for the first quarter of last year. The loss and LAE ratio was 73 percent for the first quarter of 2011 compared to 76 percent for the first quarter of last year. The decrease was primarily due to rate increases put into effect in 2010 across a number of states, especially Florida. The first quarter of 2011 included three points of favorable loss reserve development compared to two points for the first quarter of last year. Other revenues increased to $18 million in the first quarter of 2011 from $14 million in the first quarter of last year, primarily from an increase in referral fees. New policy sales increased 15 percent in the Esurance segment, driven by a 40 percent increase at Answer Financial.Gary Tolman, CEO of Esurance, said, “I was pleased with our results for the first quarter. We had good top-line growth at both Esurance and Answer Financial, driven by strong new policy sales. Answer Financial achieved record results in the quarter for new auto policy sales. Esurance’s adjusted combined ratio improved by four points compared to last year. We continue to compete successfully with our unique choice offering in a competitive personal auto insurance market.”Controlled premiums, which include policies sold by Answer Financial, were $348 million in the first quarter of 2011, up 9% compared to $320 million in the first quarter of last year. Gross premiums written by Esurance were $247 million in the first quarter of 2011, a six percent increase from the first quarter of last year. As of March 31, 2011, the segment had 892,000 policies-in-force, up six percent in the first quarter of 2011.In 2010, Esurance began reporting its expense and combined ratios on an adjusted basis, deducting referral fee revenues from acquisition expenses in order to better reflect this growing benefit, which is a by-product of its advertising expenditures. See “Regulation G” below.The GAAP total return on invested assets for the first quarter of 2011 was two percent, which included 0.8 percent of currency gains, compared to 1.4 percent for the first quarter of last year, which included 0.3 percent of currency losses.