World shares and commodities fell as lacklustre corporate earnings reports undermined investor confidence before the release of American growth data due out later on Friday.
Gloomy earnings and outlook statements from global giants like as Apple and Amazon, South Korea's Samsung and Renault and Ericsson in Europe have corroded hopes of a recovery in the global economy.
The FTSE Eurofirst 300 index of top European shares was down 0.5% with London's FTSE 100, Paris's CAC-40 and Frankfurt's DAX all around 0.5 to 0.7% lower.
Efforts by the world's major central banks to boost activity and draw a line under the euro zone debt crisis, along with signs of a recovery in the U.S. economy, have been behind a strong rally in global equity markets this year.
But investors want to see the recovery confirmed by the U.S. GDP data, especially with uncertainty growing over the budget problems in Washington, known as the fiscal cliff, which could depress business activity early next year.
"What you have now is no additional oomph coming from the central bankers and you have the data seeming to weaken if you look at the more recent evidence," said William De Vijlder, chief investment officer at BNP Paribas Investment Partners.
"On top of that you have the never ending story of what is going to happen to the (fiscal) cliff, so that is not an environment where people, would say let's now go for equities."
The MSCI world equity index was down 0.5% on Friday at 327.90 points and in line for a loss of 1.85% this week, although its is still up an impressive 9.5% for the year to date.
US stock index futures also pointed to a lower open on Wall Street on Friday though here the broad S&P 500 index <.SPI> is holding onto gains of over 12.3% for 2012.
Modest growth seen
The U.S. third quarter GDP data, due at 1230 GMT, is expected to show the world's biggest economy growing at a sluggish annual rate of 1.9%, according to a Reuters survey of economists.
The modest expansion is seen as falling short of what is needed to make much of a dent in U.S. unemployment, and will not offer much cheer for the White House a little more than a week before the November 6 presidential election.
Concerns that this level of growth will be too little to offset the slowdown caused by Europe's debt crisis and the impact is having on Asia's giant export industries also encouraged selling across the main commodity markets on Friday.
Brent crude slipped 65 cents to $107.83 a barrel extending its losses to 3% this month, with investors also reluctant to take positions before the U.S. elections.
Gold dropped more than half a% to $1,703 an ounce, and was headed for its third week of declines.
While base metals like aluminium, copper, lead, zinc, tin and nickel hit their lowest levels in roughly 1-1/2 months.
"We've got a general 'risk reduction' hitting the markets. It's hitting equities on the back of earnings concerns since big U.S. companies were not meeting earnings expectations," said William Adams, head of research at Fastmarkets.
Copper, which is widely used in power and construction industries, was down 3% for the week at $7,778 a tonne, and could be about to post its biggest weekly fall since early June.
Greenback strength
In the currency markets the dollar rose to its highest in level six weeks against a basket of currencies to 80.27, as the euro lost ground on worries over Greece and the yen staged a small recovery after heavy falls this week.
A robust GDP reading could see the greenback gain further to touch its June peak against the Japanese currency of 80.63 yen, while a poor number would see it pare the recent gains.
But the main focus was on Tokyo where traders are gearing up for the Bank of Japan to ease monetary policy next week, which would be the first time it has taken action for two consecutive months since 2003.
The dollar was actually down 0.5% at 79.95 yen on Friday as traders cut positions before the GDP report, but it is on track to end the week higher, adding to last week's gains of 1.1%.
The Bank of Japan is seen easing next week by expanding asset purchases and it may even make a stronger commitment to boost inflation to try to keep the world's third-largest economy from sliding into recession.
