Wall St dips at open after 3-day run

U.S. stocks dipped at the open on Wednesday following three days of gains on Wall Street as traders awaited more signals about central bank action in support of a stalling global economy.

The Dow Jones industrial average dropped 36.82 points, or 0.28 percent, to 13,131.78. The Standard & Poor's 500 Index lost 4.09 points, or 0.29 percent, to 1,397.26. The Nasdaq Composite Index shed 12.14 points, or 0.40 percent, to 3,003.72.