Bleak outlooks from Intel, Alcoa and Time Warner and unnerving signs about unemployment have sent stocks sharply lower.

The forecasts from industry bellwethers have caused investors to reconsider the notion that the economy might begin to rebound in the second half of the year.

The Dow Jones industrials are ending down 245 points, or 2.7 percent, at the 8,770 level. The Standard & Poor’s 500 index is down 3 percent and the Nasdaq composite is down 3.2 percent.