After a strong start the New York Stock Exchange plunged into the red again. At the beginning of the session, the Dow Jones Industrial Average had been up 50 points to 9020, with winners outnumbering losers 2-to-1, but finally the bears got the upper hand.

Investors remembered Asia's economic crisis and the turmoil on Russia's financial markets, and they sent the Dow Jones down 70.25 points to end at 8,899.95.

The loss for the week was the second-biggest of the year at 214 points. Nonetheless, share winners led the losers 17 to 12 on a moderate volume of 556 million shares traded on the New York Stock Exchange.

The Nasdaq composite index went into the red as well, losing 15.73 points to close at 1,778.89.

The Standard & Poor's 500 index ended off 6.78 points at 1090.82 - off 20 points on the week.

According to analysts, investors played safe, still baffled by the uncertainties of Asia's markets, the problems of the Russian government, and the nuclear tests in Pakistan and India. "There is a lot of concern as we head into the weekend surrounding the Asian, Russian and Indian potential crises", said Tony Dwyer, chief market strategist at Ladenberg Thalman.

There was one winner of the day: Icos Corp, which ended the day sharply higher after a report said that the biotechnology company's anti-impotence drug candidate could have fewer side effects than Pfizer's bestseller Viagra.