Flagstone Reinsurance Holdings last night announced a net loss of $326.1 million for 2011, driven by hefty catastrophe claims.The loss broke down to $4.65 per share and compared to net income of $97.1 million, or $1.23 per share, in 2010.The Class of 2005 reinsurer, now domiciled in Luxembourg, booked a fourth quarter net loss of $85.2 million, or $1.21 per share, compared to net income of $15 million, or 20 cents per share, for the same period a year earlier.Flagstone’s quarter was hit by upward revisions of loss estimates relating to catastrophes that occurred in the first half of 2011 and by the flooding in Thailand.The company saw increases of 10 to 15 percent in US reinsurance rates at January 1 renewals, while rates in Europe were up five percent and loss-affected regions up even more significantly.Chief executive officer David Brown said Flagstone “had now put 2011 behind us”. The company said it was making significant progress in divesting its Lloyd’s and Island Heritage businesses, with a shortlist of qualified purchasers in discussions for them.The company’s combined ratio, reflecting the proportion of premium dollars spent on claims and expenses, was 160.4 percent for the fourth quarter and 153.6 percent for the full year.Diluted book value of $10.90 was down by 9.6 percent for the quarter.Mr Brown said: “2011 was the worst year on record for industry losses resulting from international catastrophes, and as a global reinsurer with a historical focus on international business, our results reflected this unprecedented number of significant events.“We have now put 2011 behind us and expect that our realigned underwriting focus and our steps to streamline our operating platform will allow us to return to producing quality underwriting results.“We continued to make progress on our strategic business realignment during the fourth quarter, and we look forward to providing updates as we make progress on the divestitures. We also continue to work closely with our clients and brokers and we are pleased with our book of business at the January 1 renewal period.”Flagstone continues to execute its plan to reduce overall firm risk by cut overall gross premiums written by 30, or by around $300 million per year.