Deepening worries about global economic growth, particularly in China, set off a rout in riskier assets including technology stocks, copper and crude oil. U.S. retailers took a drubbing after Macy's reported weaker sales.
The S&P 500 index lost 21.59 points, or 0.8 percent, to 2,818.37.
The Dow Jones Industrial Average slipped 137.51 points, or 0.5 percent, to 25,162.41.
The Nasdaq composite retreated 96.78 points, or 1.2 percent, to 7,774.12.
The Russell 2000 index of smaller-company stocks skidded 21.91 points, or 1.3 percent, to 1,670.67.
For the week:
The S&P 500 is down 14.91 points, or 0.5 percent.
The Dow is down 150.73 points, or 0.6 percent.
The Nasdaq is down 64.99 points, or 0.8 percent.
The Russell 2000 is down 16.14 points, or 1 percent.
For the year:
The S&P 500 is up 144.76 points, or 5.4 percent.
The Dow is up 443.19 points, or 1.8 percent.
The Nasdaq is up 870.73 points, or 12.6 percent.
The Russell 2000 is up 135.15 points, or 8.8 percent.