The Dow Jones Industrial Average fell 17.53 points (0.18 percent) to finish at 9,771.91.

The Nasdaq composite meanwhile rose 8.12 points (0.40 percent) to 2,057.32 and the broad-market Standard & Poor's 500 index edged up 2.53 points (0.24 percent) to 1,045.41. The major indices spent most of the session in negative territory in volatile trade as investors worried about the strength of the budding U.S. recovery underway from the worst recession in decades.

"The major stock averages crawled out of an early hole and closed mixed as gains in basic materials and industrial shares offset weakness in financials and semiconductors," said Scott Marcouiller of Wells Fargo Advisors.

"Investors appeared cautious as the Federal Reserve began its meeting on interest rates and the market awaited Friday's employment report."

The market was "continuing to contemplate the sustainability of an economic recovery without global stimulus efforts," Charles Schwab & Co. analysts said.

A huge takeover bid by billionaire investor Warren Buffett's Berkshire Hathaway for the Burlington Northern Santa Fe railway company was not enough to spark a strong rally, analysts said.

Buffett said the acquisition of 77.4 percent shares in BNSF it does not already own would be Berkshire's biggest acquisition and represents "an all-in wager on the economic future of the United States."

Shares in the railway group, valued at US$44 billion including US$10 billion in debt, shot up 27.51 percent to US$97.00.

Berkshire Hathaway climbed 1.85 percent to US$3,325.35.

The Fed was expected to hold its key rates at near-zero to help the economy recover from recession when it concluded a two-day meeting yesterday.