Technology stocks, which have outrun the broader market for weeks, caused it to topple today. The Dow Jones industrials gave up a 97-point gain to finish with a loss as investors sold stocks, including AT&T and Intel.
The Dow Jones industrial average fell 70.11 points to close at 10,877.81. Broader indicators also closed sharply lower. The Nasdaq composite index fell 85.21, to 3336.16, its worst point loss since Sept. 23. The Standard & Poor's 500-stock index fell 18.76, to 1389.07.
For most of the day, blue chips attracted buyers even as investors sold technology stocks to lock in profits from their big run in the past few weeks.
But as the Nasdaq's losses widened, the broader market dropped, said Gary Kaltbaum, chief technical analyst at J.W. Genesis Securities in Boca Raton, Fla.
"As technology goes, it will take the rest of the market with it," he said. "Technology makes up so much of the S&P 500, and an increasing share of the Dow, that most averages can't hold up without it."
Indeed, over the course of the day, losses spread from newer technology companies such as Yahoo and Amazon.com to more established businesses such as Intel, which ended down 2 1/4, at 76-11/16.
Amazon.com fell 5 3/8, to 85-1/16, and Yahoo plunged 13 3/8, to 212 3/4, during the regular trading session. But during the Nasdaq's extended trading hours, Yahoo soared back to 233 on the news that it will be added to the S&P 500 after the close of trading on Dec. 7.
Stocks typically rise when they are added to the index because fund managers who try to mirror the index will buy the shares.
The Nasdaq has had 16 record-high closes since Oct. 29, a huge run that left the technology-dominated index with a 12.5 percent gain for November, even after today's steep loss. By contrast, the Dow rose just 1.4 percent during the month.