Aetna profit misses analysts' target, shares fall (Reuters) - Health insurer Aetna Inc reported a lower-than-expected quarterly profit on Thursday as higher claim costs and administrative expenses weighed on results, and shares fell nearly 9 percent. Aetna, whose shares had outperformed rivals this year, is the first major health insurer to miss earnings estimates for the first quarter, after WellPoint Inc and UnitedHealth Group Inc posted higher-than-expected profits and raised their full-year outlooks. Aetna, the No. 3 U.S. health insurer, backed its full-year profit view. "The first quarter miss is clearly disappointing, but revenue and medical costs closely tracked our estimates, suggesting to us the company's full-year 2012 EPS guidance remains achievable," Susquehanna Financial Group analyst Chris Rigg said. Some analysts also were expecting Aetna to recognize gains from money set aside to pay for medical claims from prior periods, which the insurer did a year ago but not in the 2012 first quarter. Aetna shares fell 8.8 percent to $45 in premarket trading. Through Wednesday, Aetna shares had risen about 17 percent this year, compared with a 14 percent rise for the Morgan Stanley Healthcare index of health insurers. Health insurers largely posted higher-than-expected profits in 2011 because of Americans' low use of medical services in the weak economy, leading their shares to far outperform the broader stock market. Aetna's first-quarter net income fell to $511 million, or $1.43 per share, from $586 million, or $1.50 per share, a year earlier. Excluding items, earnings of $1.34 a share missed the analysts' average estimate by 6 cents, according to Thomson Reuters I/B/E/S. Revenue rose 6 percent to $8.92 billion. Aetna spent 81.5 percent of premium revenue on medical claims, up from 79.2 percent a year earlier. Its operating expenses rose nearly 7 percent. Aetna's membership stood at 17.92 million at the end of March, up 0.6 percent from a year ago. The company expects enrollment to swell to 18.2 million by year-end. The insurer still expects operating earnings per share of about $5.00 for 2012. Analysts are looking for $5.15. Reporting By Lewis Krauskopf in New York; Editing by Lisa Von Ahn and Gerald E. McCormick