OKLAHOMA CITY -- For investors pained by UnitedHealth's ( UNH) weak forecast, WellPoint ( WLP) offered little comfort. Unlike its struggling rival -- which last week lowered its long-term growth rate -- WellPoint has promised to keep increasing annual profits by at least 15% next year. But the company has reported mixed results for the third quarter, sending its shares modestly lower. Revenue rose just 5.2% to $15 billion, missing Wall Street targets, as enrollment gains remained weak. But profits jumped 7.1% to $868 million, with earnings per share of $1.45 topping the consensus estimate by a penny. Cost controls and share repurchases offset rising medical expenses, leading to that upside. WellPoint's all-important medical loss ratio ticked up to 81.8% in the latest quarter, disappointing those who had been looking for a decline. The company - which had forecasted possible improvements in this metric itself - blamed a special Medicare-related charge for much of the deterioration. Specifically, WellPoint underestimated the risk it shared under the Medicare Part D program and suffered a negative prior-period reserve development as a result. "We are surprised that the company misestimated this amount by such a wide margin," Credit Suisse analyst Gregory Nersessian fretted on Wednesday. "While we understand the Medicare true-up is a one-time item related to 2006 and 2007 claims experience, it is an uncharacteristic mistake for a company that prides itself on its actuarial discipline."