After Thursday's respite, the tech-infused Nasdaq composite index dropped 64.61 to 1,720.39 Friday. The S&P 500 fell 23.01 to 1,128.43, and the Dow Jones industrial average slid 126.96 to 9,791.09.
Wall Street pessimism was reinforced by a government report showing the economy shed more jobs in any month since 1991. The data fueled fear that the nation's record 10-year-old economic expansion is slowing so rapidly it could be heading toward a recession.
"People are bracing themselves for a slide now," said John Forelli, senior vice president at Independence Investment Associates. "Every piece of data that comes is pushing off the possibility of a second-half economic recovery, and then it becomes a fourth-quarter recovery. The further it gets pushed out, the less likely people are going to step up to the plate and buy."
The European Commission confirmed Friday that it was investigating the business practices of U.S. computer chip giant Intel. The company's shares were down $2 to $23.63.
Telecommunications equipment makers Sycamore Networks, down $1.81 to $7.25, and Extreme Networks, down 5 cents to $15.96, fell after warning that their third quarters wouldn't live up to the Street's expectations.
Tellabs, off $7 to $33.75, slashed its first-quarter targets for the second time, adding yet another warning to the long list from telecommunications equipment makers.
Network services provider Illuminet Holdings, up $3 to $21.50, raised its first-quarter earnings forecast, saying it believes its business model is solid enough to weather the economic slowdown hurting the telecommunications sector.
Amazon.com was off 75 cents to $8.37; AOL Time Warner lost 40 cents to $39.30, and Yahoo lost 44 cents to $14.81.
Cisco Systems fell $1.31 to $13.63; Oracle shed 90 cents to $13.84, and Microsoft was down 56 cents to $56.19.
Staff and Reuters contributed to this report.