The main US share indexes fell sharply on Friday, hit by ongoing concerns about the impact of the US mortgage debt crisis on leading banks.
The markets are fearful of yet more banking losses
Fourth largest lender Wachovia sparked the latest share falls after it said its losses on bad mortgage debt would total $1.1bn (£525m) for October alone.
Its admission, just the latest from a major US bank, saw the Dow Jones index end down 224 points or 1.7% to 13,042.
The Nasdaq index also fell heavily, down 68 points or 2.6% to 2,628.
Dominated by technology companies, sentiment on the Nasdaq was further hit by weak results from wireless telecoms firm Qualcomm.
The bad debt crisis centres on sub-prime home loans.
As US mortgage rates have risen sharply over the past year, the sub-prime sector, which specialises in loans to people with poor credit histories or those on low incomes, has seen record levels of loan defaults.
The losses US banks have had to swallow are twofold.
Firstly, their direct exposure to bad sub-prime debt, and secondly, the knock-on fall in the value of all mortgage debt.
This situation has been exacerbated by the fact the banks have, in recent years, increasingly packaged their sub-prime debt into wider debt packages called collateralised debt obligations (CDOs), which are then sold on to investors.
Yet with investor confidence at rock bottom, banks have struggled to find buyers for these CDOs, which have thus fallen in value.
This has sparked the wider credit crisis as banks and other lenders have been less willing to lend to each other.
"The problem right now isn't so much the size of the write-down at Wachovia, as it is the belief that the market is going to be stuck with these write-down announcements from the sector for some time," said analyst Patrick O'Hare of Briefing.com.
The Standard & Poor's 500 index ended down 23 points, or 1.5% to 1,452.12.