Wall Street has had yet another dismal day, extending its heavy losses as investors' worries about the financial sector wiped out early enthusiasm over the Federal Reserve's efforts to inject confidence into the credit markets.

Trading remained fractious and grew more turbulent in the last hour, with the Dow Jones industrial average losing more than 500 points and all the major indexes falling more than five percent.

This latest plunge, which followed a big drop on Monday, came after Bank of America Corp. reported its third-quarter profits fell 68 percent. The market's gloom was also fed by comments from Fed Chairman Ben Bernanke, who warned that the financial crisis could prolong the difficulty the economy is facing.

The Dow is down 508, or 5.11 percent, at the 9,447 level, after falling nearly 370 Monday. The broader Standard & Poor's 500 index is down 5.73 percent and the Nasdaq composite index is down 5.80 percent.