By Christina Cooke (The Guardian)

U.S. stocks were little changed on Wednesday, halting the previous session's rally, as doubts arose that the Federal Reserve-led move to ease credit market strains would work.

Health-care stocks were among the biggest drags. Shares of Humana, one of the biggest Medicare plan providers, fell 27 percent to $34.57 after the company cut its first-quarter earnings forecast nearly by half. For details, see ID:nN12144867.

Dow component Caterpillar , the world's largest maker of construction and mining equipment, lent some support to the blue-chip average. Caterpillar upped its forecast for 2010 revenue, crediting in part continued worldwide infrastructure spending. Shares of the company, seen as an economic bellwether, rose 3 percent to $74.49.

The Dow Jones industrial average was up 20.19 points, or 0.17 percent, at 12,177.00. The Standard & Poor's 500 Index was down 0.93 point, or 0.07 percent, at 1,319.72. The Nasdaq Composite Index was down 3.05 points, or 0.14 percent, at 2,252.71.

Major U.S. stock indexes jumped more than 3 percent on Tuesday after a coordinated central bank move to add billions of dollars of liquidity to struggling credit markets. But persistent concerns about the health of the economy led investors to use the gains as an opportunity to take profits.

"I think the air is being let out of the balloon of yesterday's run-up. I would not be completely convinced that this test is finished yet," said Bruce Zaro, chief technical strategist at Delta Global Advisors in Boston.

"We're still seeing people selling into any rally."

Other health-care companies also fell, with UnitedHealth Group Inc shares off 8.1 percent to $35.11. Humana's lower outlook comes a day after a gloomy forecast from rival WellPoint Inc sent the entire health insurance industry reeling.

On Tuesday, the Dow and Nasdaq rang up their biggest daily percentage gains since March 2003 after the Fed said it was expanding a lending program and will accept a broader base of securities as collateral, including mortgage bonds whose value has declined as the housing bubble burst.