U.S. stocks fell Thursday in another frenzied session as investors try to gauge how monetary policy and the prospects for the economy will affect corporate profits and stock valuations.

The Dow Jones Industrial Average fell 7.31 points, or less than 0.1%, to 34160.78, after rising as many as 600 points in the morning. The S&P 500 lost 23.42 points, or 0.5% to 4326.51, while the Nasdaq Composite fell 189.34 points, or 1.4%, to 13352.78.