Stocks in the United States have fallen before an address by the head of the Federal Reserve.
Chairman Ben Bernanke is due to address central bankers at a symposium in Jackson Hole, Wyoming, on Friday.
His speech last year laid the groundwork for a $US600 billion bond-buying programme to revive the economy in a second round of stimulus, known as quantitative easing.
Stocks on Thursday rose initially after Berkshire Hathaway took a $US5 billion stake in Bank of America, whose shares had fallen to two-year lows earlier this week.
But new unemployment claims rose last week, suggesting the job market is still struggling.
There is also speculation that Germany will follow the example of other European nations and ban short selling in financial stocks.
The Dow Jones Index fell 171 points, or 1.5%, to close at 11,150. The Nasdaq Composite was down 48 points, or 2%, to end at 2420.
In Europe: the FTSE 100 in London was down 1.4%, the DAX in Frankfurt was down 1.7% and the CAC-40 in Paris was down 0.6%.
The Nikkei in Japan was up 133 points to 8772.
The Australian 200 Index was up 45 points, or 1%, at 4213. The NZX 50 rose 14 points, or 0.4%, to 3302.
At 8.25am on Friday, the New Zealand dollar was trading at 82.82 US cents, 79.35 Australian cents, 50.77 pence, 64.10 yen and 0.5752 euro. The Trade Weighted Index was at 71.24.
Brent crude oil fell to $US112.71 per barrel and gold was trading at $US1755.79 per ounce.