Wall Street surged on a burst of optimism Monday, propelling the Dow Jones industrials up more than 400 points on more signs of a reviving credit market and comments from Federal Reserve Chairman Ben Bernanke.

Investors who had sold furiously in recent weeks in response to immobile credit markets became more optimistic as bank-to-bank lending rates eased further. There’s also less demand for the safest Treasury bills. And Bernanke has hinted that the government will take more steps to help the economy.

The improvement in lending rates helped to temper concerns about tight credit contributing to a prolonged recession, but Bernanke still warned that the economy is likely to be “weak for several quarters, and with some risk of a protracted slowdown.” He told the House Budget Committee that a fresh round of government moves might help ease the country’s economic weakness.

The S&P 500 rallied 44.85, or 4.8 percent, to 985.40. The Dow surged 413.21, or 4.7 percent, to 9,265.43, with all 30 of its companies increasing. The Nasdaq Composite Index rose 58.74, or 3.4 percent, to 1,770.03. More than five stocks advanced for each that fell on the New York Stock Exchange.

(Bloomberg / Associated Press)