U.S. stocks fell sharply at the open on Thursday as an increase in the number of workers filing for jobless benefits and concerns over the fiscal health of Greece made investors worry about the state of the global economy.

The Dow Jones industrial average <.DJI> dropped 155.15 points, or 1.50 percent, to 10,219.01. The Standard & Poor's 500 Index <.SPX> fell 15.89 points, or 1.44 percent, to 1,089.35. The Nasdaq Composite Index <.IXIC> lost 32.78 points, or 1.47 percent, to 2,203.12.

(Editing by Jeffrey Benkoe)