Health insurer WellPoint Inc posted slightly lower first-quarter profit on Wednesday, hurt by large investment losses, but results far surpassed Wall Street forecasts.

WellPoint lifted the lower end of its 2009 profit forecast, but maintained the high end.

Net income at the largest U.S. health insurer by membership fell to $580.4 million from $588.1 million. Earnings per share rose to $1.16 from $1.07 a year earlier when the company had more shares outstanding.

Results in the 2009 quarter included net realized investment losses of $228.4 million, or 46 cents per share. Excluding those losses, earnings were 37 cents ahead of the average estimate of analysts, according to Reuters Estimates.

Revenue fell 0.4 percent to $15.3 billion.

WellPoint's benefit expense ratio, which measures the percent of premiums spent on medical costs, improved substantially to 81.6 percent from 85.1 percent a year ago. Analysts at UBS had expected 83.8 percent.

The Indianapolis-based company cited disciplined pricing and operational improvements in its Medicare plans for seniors and health plans for local businesses.

WellPoint expects 2009 earnings of $5.14 to $5.20 per share including the investment losses -- which equates to $5.60 to $5.66 excluding them. In February, WellPoint forecast $5.51 to $5.66 per share for 2009 excluding any potential investment losses.

On Tuesday, rival UnitedHealth Group Inc posted sharply higher-than-expected earnings, but shares fell after it refrained from raising its full-year profit forecast.

WellPoint shares are down about 1 percent in 2009, compared with a 9 percent drop for the S&P Managed Health Care index <.GSPHMO>, amid wide concerns over the financial impact of U.S. health reform measures.

(Reporting by Lewis Krauskopf; Editing by Derek Caney)