NEW YORK — Federal Reserve Chairman Ben Bernanke gave Wall Street a double dose of reassurance, but don't expect the markets to calm down overnight.

Bernanke told Congress yesterday the recession might end this year, and that regulators aren't planning to nationalize banks. The news alleviated some of investors' worries about the economy and the banking industry, and lifted market indexes off their lowest levels since 1997.

Stocks remain on shaky ground, however. Bernanke may have helped stem the market's slide yesterday, but the market also found stability from temporary technical factors: bargain-hunting, the unwinding of short bets, and selling exhaustion after six straight down days for the S&P 500.