Wall Street plunged again lower today amid renewed fears that the financial sector’s troubles with bad credit won’t soon end and that some consumers are buckling under signs of a slowing economy. The Dow Jones industrials finished down nearly 250 points.

The arrival of earnings season has investors worried about how banks and brokerages have fared after suffering losses in the collapse of the subprime mortgage market. Traders appeared to grow more pessimistic ahead of reports next week from the nation’s biggest financial institutions. Merrill Lynch & Co., Citigroup Inc., and JPMorgan Chase & Co. are all slated to weigh in next week.

Adding to investors’ unease, Merrill Lynch might take a $15 billion hit from its exposure to soured subprime mortgage investments, according to The New York Times. The nation’s largest brokerage is also said to be seeking another capital infusion to help shore up its balance sheet.

Investors also grew nervous after American Express Corp. warned late yesterday that slower spending and more delinquencies on credit card payments will hamper profit throughout 2008. A profit warning from Tiffany & Co. added to Wall Street’s unease about the fortitude of the consumer.

Today’s session revealed the extent of investors’ misgivings about the financial sector’s efforts to sew up its troubles. Bank of America Corp. agreed today to buy Countrywide Financial Corp. for $4 billion, a deal that rescues the country’s largest mortgage lender but pays less than the company’s market value.

According to preliminary calculations, the Dow fell 246.69, or 1.92%, to 12,606.30. The Dow had been down more than 300 points in the last hour.

Broader stock indicators also declined. The Standard & Poor’s 500 index fell 19.31, or 1.36%, to 1,401.02, and the Nasdaq composite index fell 48.58, or 1.95%, to 2,439.94.