Humana Inc forecast a profit for this year below Wall Street estimates, suggesting that investors may be overestimating how much it will earn from a burgeoning Medicare business, and its shares fell almost 6 percent.

Humana, one of the largest providers of Medicare health insurance plans for U.S. seniors, also posted a fourth-quarter profit that was in line with analyst estimates, another disappointment after the company's earnings exceeded expectations for most of 2011.

The Street has gotten ahead of itself a little bit, Morningstar analyst Matthew Coffina said. There is upside to the guidance they put out there ... but I think the Street was maybe discouraged by them not being a little more optimistic.

Humana and its peers who also specialize in Medicare plans they administer on behalf of the government hope to benefit from providing services to an aging U.S. postwar population. Shares in Humana soared 60 percent last year alone.

Humana raised its 2012 earnings outlook to a range of $7.50 to $7.70 per share from its prior projection of $7.40 to $7.60. Analysts, on average, expect $7.99.

For this early in the year, consensus was 6.5 percent above the guidance. That's a lot, Jefferies & Co analyst David Windley said. To have an expectation that management would move to that after one month of data ... is pretty aggressive.

After Monday's results, some investors may have been selling to lock in profits, said Les Funtleyder, a portfolio manager with Miller Tabak.

The results were good; expectations were too high, said Funtleyder.

Humana raised its forecast for membership additions to its Medicare Advantage enrollment by 40,000. It now expects to add about 190,000 individual members to such plans this year.

ADDING TO MEDICARE ROLLS

Health insurers had performed well beyond expectations for most of 2011, benefiting from lower medical claims costs as a weak economy kept more Americans out of the doctor's office.

But their financial results have been more tepid in the latest quarter, and some are expecting those claims costs to pick up this year. Besides Humana, Cigna and UnitedHealth Group Inc also forecast 2012 profit that fell short of Wall Street targets.

Humana's quarterly net income rose to $199 million, or $1.20 per share, from $107 million, or 63 cents per share, a year earlier.

Earnings were in line with Wall Street's average estimate, according to Thomson Reuters I/B/E/S. Excluding a charge of 13 cents a share for its charitable fund, earnings would have been 11 percent above expectations, according to Jefferies' Windley.

Revenue rose 9 percent to $9.06 billion, below the $9.24 billion that analysts expected.

Medicare Advantage enrollment stood at 1.64 million at the end of December, up 12 percent from a year earlier. The company gained 173,000 members in January, reflecting results from the annual enrollment period for 2012.

Humana shares were off 5.8 percent to $84.89 in afternoon trading on the New York Stock Exchange. Through Friday they were up 3 percent this year.

(Reporting By Lewis Krauskopf; Editing by John Wallace and Mark Porter)

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