U.S. stocks fell sharply on Friday, with benchmark indexes falling for a third week in a row, as computer-chip manufacturers led the losses after Microchip Technology lowered its sales outlook.
"With the Fed going away, and the slowdown in Europe, the market is trying to figure out are these valuations fair, that's what this whole week has been about," said JJ Kinahan, chief strategist at TD Ameritrade..
Equities fell further after Standard & Poor's downgraded its outlook for France to negative from stable.
The CBOE Volatility Index, a measure of investor uncertainty, rose above 20 for the first time since early February, and spiked 13 percent to 21.24.
"Adding insult to injury after the bell on Thursday was a revenue warning from the CEO at Microchip Technology," noted Andrew Wilkinson, chief market strategist at Interactive Brokers.
"Investors may have to worry beyond Friday about the consequences of the Microchip warning," he added.
Juniper Networks declined after posting initial third-quarter results that came in below its own forecast.