Urgent: U.S. stocks open sharply lower following global rout

U.S. stocks opened sharply lower Friday, as a heavy sell-off in global markets and a plunge in oil prices rattled nervous investors.

Shortly after the opening bell, the Dow tumbled 1.87 percent, and the S&P 500 shed 1.75 percent, while the Nasdaq slumped 3.06 percent. Endi