DOW JONES NEWSWIRES FPL Group Inc. (FPL) reported a 53% jump in first-quarter earnings on mark-to-market gains at its generation business. The company also reported higher retail sales, a reversal from last year as demand slumped amid the recession at utilities nationwide. Earnings climbed to $556 million, or $1.36 a share, compared with $364 million, or 90 cents a share, a year earlier. The latest quarter included 42 cents in mark-to-market and other impacts related to NextEra Energy Resources, its power-generation business. Revenue fell 2.2% to $3.62 billion. Analysts' mean estimates were for earnings of 87 cents on revenue of $3.68 billion. Earnings jumped at Florida Power & Light on a 6.6% increase in retail energy sales as weather was colder than normal this winter in the Sunshine State. NextEra's earnings fell 14% excluding the gains. Shares of FPL, which reiterated its 2010 earnings forecast, closed Monday at $51.06 and were inactive premarket. -By Kevin Kingsbury; Dow Jones Newswires; 212-416-2354; kevin.kingsbury@dowjones.com