The Dow industrial average <.DJI> fell for the fourth straight day on Wednesday, while the S&P 500 and Nasdaq gained although well off their session highs, after the U.S. Federal Reserve reiterated concerns about the economic outlook.

Based on the latest available data, the Dow Jones industrial average <.DJI> fell 23.05 points, or 0.28 percent, to close unofficially at 8,299.86 -- capping a fourth straight daily decline for the blue-chip average.

But the Standard & Poor's 500 Index <.SPX> gained 5.84 points, or 0.65 percent, to finish unofficially at 900.94, below its session high at 910.85. The Nasdaq Composite Index <.IXIC> rose 27.42 points, or 1.55 percent, to end unofficially at 1,792.34, off its session high at 1,807.08.

(Reporting by Ellis Mnyandu; Editing by Jan Paschal)