Wall Street opens higher after Fed plan

Dow Jones, S&P 500 index and Nasdaq up 0.5% each

U.S. stocks opened higher on Friday, putting the S&P 500 on track for a fourth straight gain in the wake of an aggressive plan by the Federal Reserve to stimulate the economy.

The Dow Jones industrial average  was up 29.66 points, or 0.22 percent, at 13,569.52. The Standard & Poor's 500 Index  was up 3.74 points, or 0.26 percent, at 1,463.73. The Nasdaq Composite Index  was up 11.24 points, or 0.36 percent, at 3,167.07.