Stocks in the United States slid in a broad sell-off on Thursday.
Markets were under severe selling pressure after a downgrade was issued by Standard & Poor's for Britain's triple-A credit rating.
Investors fear the United States could face a similar fate.
Latest unemployment data was also weaker than expected. But the number of people filing new claims for jobless benefits declined by 12,000 last week.
Shares of big manufacturers dropped: United Technologies Corp fell 1.9% to $US50.76 and Boeing Co shed 2.9% to $US43.29. Apple Inc was down 1.3% at $US124.18.
The Dow Jones industrial average dropped 129.91 points, or 1.54%, to 8,292.13.
Standard & Poor's 500 Index fell 15.14 points, or 1.68%, to 888.33. The Nasdaq Composite Index lost 32.59 points, or 1.89%, to 1,695.25.
Trading was moderate on the New York Stock Exchange, with about 1.44 billion shares changing hands - below last year's estimated daily average of 1.49 billion.
About 2.24 billion shares were traded on the Nasdaq - below last year's daily average of 2.28 billion.