Stocks ended sharply lower after a late-afternoon slide.
The losses extended a downturn in the market last week which gave indexes their worst weekly performance in more than two years.
At the close on Wall Street the Dow Jones industrial average was down 223.03 points, or 1.35 percent, at 16,321.07. The Standard & Poor's 500 index also was down 31.39 points at 1,874.74. The Nasdaq composite lost 62.58 points to 4,213.66.
ENERGY SECTOR SLUMPS: Energy stocks fell nearly 3 percent, much more than the rest of the market. Investors have been dumping those stocks as the price of oil continues to fall.
The price of oil has been slumping as fears of waning demand grow even as production remains high.
THE QUOTE: "The market is basically dealing with the same issues that it was dealing with last week," said Krishna Memani, chief investment officer at OppenheimerFunds. "If the market is going to break out of its recent funk ... it will be because earnings came out in line, and more importantly, the guidance in these earnings calls is far more constructive than what the slow growth environment makes you believe."
TURBULENT WEEK: U.S. stocks swung wildly last week and ended lower. The S&P 500 fell 3.1 percent, its worst weekly performance since a 4.3 percent decline in May 2012. The main factor weighing on stocks has been concern over global growth.