CORRECTION: Wall Street ends lower on rate uncertainty

(Corrects to show in 9th paragraph that Research in Motion was the top drag on the Nasdaq 100, not on the Nasdaq)

By Jennifer Coogan

NEW YORK (Reuters) - Stocks fell on Wednesday after the Federal Reserve trimmed interest rates but left unclear the outlook for further rate cuts, prompting profit-taking as the Standard & Poor's 500 index ended its best month since December 2003.

The Fed's failure to deliver an unequivocal statement that the worst was over for the economy caused investors to sell their best performers in the recent rally, led by tech stocks Apple Inc (AAPL.O: Quote, Profile, Research) and Research in Motion (RIM.TO: Quote, Profile, Research) (RIMM.O: Quote, Profile, Research).

Stocks had risen early in the day after quarterly results from blue chips General Motors Corp (GM.N: Quote, Profile, Research) and Procter & Gamble Co (PG.N: Quote, Profile, Research) topped Wall Street expectations and stronger-than-expected economic data eased recession fears.

But the three major indexes shed their gains after the release of the Fed's statement, which left the outlook for further cuts clouded. Short-term rate futures suggested a 1-in-4 chance of a future cut, up from no chance before the end of the Fed meeting.

"Everything I heard coming into today was there could be signals of a pause. It's not seeming like that language was in there, so I think that's what people are reacting to," said Eric Kuby, chief investment officer at North Star Investment Management Corp in Chicago."

Stocks rebounded this month from a miserable March, as the Fed flooded the financial system with cash in the wake of Bear Stearns' collapse and amid signs frozen credit markets are beginning to thaw.

The Dow Jones industrial average finished down 11.81 points, or 0.09 percent, at 12,820.13. The Standard & Poor's 500 Index fell 5.35 points, or 0.38 percent, at 1,385.59. The Nasdaq Composite Index was down 13.30 points, or 0.55 percent, at 2,412.80.