A period of low catastrophe activity helped Bermuda reinsurer Platinum Underwriters Holdings Ltd to post net income of $67.5 million for the second quarter.The profit broke down to diluted earnings per common share of $1.97 for the second quarter.The results for the quarter include net premiums earned of $145.1 million, net favourable development of $23.2 million, net investment income of $26.2 million and net realised gains on investments of $25 million.Michael Price, Platinum’s chief executive officer, said: “Our results reflect favourable non-catastrophe prior period development, strong investment results on a total return basis and active capital management.“Catastrophe activity did not meaningfully impact our results this quarter. Our book value per common share grew to $51.84 as of June 30, 2012, an increase of 5.8 percent from March 31, 2012.“With our strong balance sheet, low expense structure, specialised analytic capabilities, and broad market access, we are well positioned to participate in those underwriting and investment opportunities that may exist during this soft portion of the insurance pricing cycle.”Net income was $67.5 million and diluted earnings per common share were $1.97. Gross premiums written were $141.2 million.Shareholders’ equity was $1.7 billion as of June 30, 2012, an increase of $31 million (or 1.8 percent) from the end of last year. Book value per common share was $51.84 as of June 30, based on 33.2 million common shares outstanding, an increase of $4.25 (or 8.9 percent) from $47.59 as of the end of last year.During the quarter, the company repurchased an aggregate of 1.65 million of its common shares for $60.4 million at a weighted average cost, including commissions, of $36.51 per share.The combined ratio, which reflects the proportion of premium dollars spent on claims and expenses, was 76.3 percent.