Stocks fell at the open on Friday in a light day on the economic calendar, but the benchmark S&P 500 index remained on track for its third straight weekly advance.

The Dow Jones industrial average <.DJI> dropped 6.36 points, or 0.05 percent, to 12,973.94. The Standard & Poor's 500 Index <.SPX> dipped 1.26 points, or 0.09 percent, to 1,372.83. The Nasdaq Composite Index <.IXIC> shed 2.54 points, or 0.08 percent, to 2,986.43.

(Reporting By Chuck Mikolajczak; Editing by Padraic Cassidy)