Analysts blamed heightened fears about Egypt, uncertainty about plans by the U.S. Federal Reserve to end its quantitative easing program and missed expectations in earnings reports.
The Dow Jones industrial average finished the week at 15,081.47 after losing 30.72 or 0.2 percent on the day. For the week, the Dow was off 416.85 or 2.69 percent.
On the New York Stock Exchange 1,078 issues advanced and 2,021 declined on total trading volume of 3.2 billion shares.
The Standard & Poor's 500 gave up 5.49 points or 0.33 percent to close at 1,655.83 and the Nasdaq dropped 3.34 points or 0.9 percent to close at 3,602.78.
In Asia, Japan's Nikkei 225 lost 102.83 or 0.75 percent to close at 13,650.11 and the Hang Seng index in Hong Kong dropped 21.44 points or 0.1 percent to 22,517.81.
European markets were higher. The London FTSE 100 added 16.65 points or 0.26 percent to close at 6,499.99, the German DAX gained 15.65 points or 0.19 percent to 8,391.94 and the French CAC 40 was up 30.69 points or 0.75 percent to 4,123.89.
The 10-year U.S. treasury note shed 15/32 to yield 2.829 percent.
In after-hours trading, crude oil was up 31 cents to $107.50 a barrel on the New York Mercantile Exchange. On the Comex division, gold rose $14.10 to close at $1,375 per troy ounce and silver gained 26 cents to close at $23.245.
The euro fell against the dollar to $1.3328 while the dollar rose to 97.53 yen.
On the Chicago Board of Trade December corn fell 9 1/4 cents to $4.63 a bushel, November soybeans shed 7 cents to $12.58 1/2 and December wheat dipped 6 cents to $6.43 1/2.