Platinum Underwriters Holdings Ltd posted a net loss of $157.2 million first quarter after taking a near quarter billion dollar hit from catastrophes during the first three months of 2011.The insurer posted catastrophe losses of $248.1 million, net of retrocession and reinstatement premiums, including $136.9 million from the New Zealand earthquake, $86.6 million from the Japan’s Tohoku earthquake and $24.6 million asa a result of the Australian floods and Cyclone Yasi.The loss compared to a profit of $15.4 million for the same period in 2010, while net premiums earned dropped to $182.9 million from $194.8 million over that period and net premiums written were down more than $50 million at $194.8 million from $247.4 million.Net favourable development was $33.1 million, net investment income and net realised gains on investments $32.8 million.Michael Price, Platinum’s CEO, said: “There were numerous natural catastrophes in the first quarter of 2011 that gave rise to significant insured losses. Our book value per common share was $44.68 as of March 31, 2011, a decrease of 11 percent from December 31, 2010, reflecting strong non-catastrophe performance, the negative impact of catastrophe losses and the repurchase of options on the company’s common shares.“Due to the accumulation of international catastrophe losses in the past 15 months in combination with changes to vendors’ catastrophe models, we generally expect property catastrophe reinsurance rates to improve for the balance of the year and the upcoming renewal period will allow us to benefit from a rising rate environment.“While it has been a challenging start to 2011, we are well positioned to take advantage of quality reinsurance underwriting opportunities as they may arise.”Platinum’s combined ratio - which reflects the percentage of premium dollars spent on claims and expenses - more than doubled from 98.7 percent for the first three months of 2010 to 200.4 percent for the same period this year.Net investment income dropped to $32.4 million from $37.5 million, while net realised gains on investments were down at $407,000 from $5.5 million over the prior-year period.Total assets were $4.62 billion as of March 31, an increase of $2.5 million (or 0.1 percent) from $4.61 billion as of December 31, 2010. Fixed maturity investments and cash and cash equivalents were $4.14 billion as of March 31, 2011, a decrease of $72.2 million (or 1.7 percent) from $4.21 billion as of December 31, 2010.Shareholders’ equity was $1.67 billion, a decrease of $230.3 million (or 12.1 percent) from $1.9 billion as of December 31, 2010. Book value per common share was $44.68.During the first quarter, Platinum repurchased 762,000 common shares for approximately $33.9 million at a weighted average cost, including commissions, of $44.50 per share. The company also purchased 2.5 million options held by RenaissanceRe Holdings Ltd for $47.9 million on January 20.