U.S. stocks fell at the open on Monday as investors worried about the strength and timing of an economic recovery, with a drop in oil and commodity prices weighing down shares in those sectors.

The Dow Jones industrial average <.DJI> dropped 66.28 points, or 0.80 percent, to 8,214.46. The Standard & Poor's 500 Index <.SPX> fell 7.45 points, or 0.83 percent, to 888.97. The Nasdaq Composite Index <.IXIC> shed 15.11 points, or 0.84 percent, to 1,781.41.

(Reporting by Rodrigo Campos; Editing by Padraic Cassidy)