Washington - US stock indices posted steep drops Friday, plunging more than 3.5 per cent to end another week of uncertainty over the state of the global economy.

The sell-off in New York followed even sharper falls in Europe, Asia and the Middle East earlier in the day on fears of a recession following the widening financial crisis.

The downturn came despite some improvement in the US housing market at the centre of the credit crisis. The National Association of Realtors said existing home sales rose an unexpected 5.5 per cent in September, partly due to bargain prices fed by a record number of foreclosures since 2007.

The Dow Jones Industrial Average tumbled 312.30 points, or 3.59 per cent to 8,378.95. The broader Standard & Poor's 500 lost 31.34 points, or 3.45 per cent, to 876.77. The technology heavy Nasdaq Composite Index fell 51.88 points, or 3.23 per cent, to 1,552.03.

For the week, the Dow dropped 5.4 per cent, the S&P 500 lost 6.8 per cent and the Nasdaq was down 9.3 per cent.

Both the S&P 500 and Nasdaq have fallen more than 40 per cent since the start of 2008 as a global credit crunch has wreaked havoc with markets worldwide. The Dow has tumbled nearly 37 per cent.

On currency markets, the dollar fell to its weakest level against the Japanese currency in 13 years, trading at 94.21 yen compared to 97.26 yen on Thursday. The US currency rose against the euro to 79.21 euro cents from 77.37 euro cents on Thursday. (dpa)