Aetna Inc. posted a remarkably low quarterly profit, on Friday. Its fourth-quarter net income fell to $165.9 million, or 38 cents per share, from $194.7 million, or 42 cents per share, the previous year.

Aetna had previously warned the investors that 2010 would be a repositioning year.

The company spent 85 percent of premium revenue on medical costs, compared with 80.6 percent, the previous year.

Its life, disability and long-term care products business posted an operating loss of $14.1 million, compared with the previous year's earnings of $17.7 million.

The company said it had to boost its disability reserves by about $50 million, in part to handle longer disability claim durations.

It also had to suffer the higher costs for pensions for its employees. The company forecasts operating earnings per share of $2.55 to $2.65 for 2010.