Energy companies led the decline. Financial stocks also fell sharply after investors weighed quarterly earnings from several big banks. Bond prices rose, sending yields lower.
The Dow Jones industrial average slid 138.61 points, or 0.7 percent, to 20,453.25.
The Nasdaq composite lost 31.01 points, 0.5 percent, to 5,805.15.
The Russell 2000 index of small-company stocks gave up 13.96 points, or 1 percent, to 1,345.24.
For the week:
The S&P 500 is down 26.59 points, or 1.1 percent.
The Dow is down 202.85 points, or 1 percent.
The Nasdaq is down 72.66 points, or 1.2 percent.
The Russell 2000 is down 19.32 points, or 1.4 percent
For the year:
The S&P 500 is up 90.12 points, or 4 percent.
The Dow is up 690.65 points, or 3.5 percent.
The Nasdaq is up 422.03 points, or 7.8 percent.
The Russell 2000 is down 11.89 points, or 0.9 percent