NEW YORK — Wall Street joined in a worldwide cascade of despair Monday over the financial crisis, driving the Dow Jones industrials to their biggest loss ever during a trading day. Even a big afternoon rally failed to keep the Dow from its first close below 10,000 since 2004.

At its worst point, the Dow was down more than 800 points, an intraday record. The stock market rallied during the final 90 minutes of the trading day, and the Dow finished down about 370 points at 9,955.50.

The average is down almost 30 percent from its all-time high of 14,164.53, set a year ago Thursday.

Speculation among traders late in the session that the market's pullback had been severe enough to force the Federal Reserve into taking other steps to soothe the markets helped stocks rebound from their lows.

"If you can't say that we're oversold now I don't know what you say. You're at least due for a bounce if nothing else," said Bill Stone, chief investment strategist for PNC Wealth Management.

The crush of selling Monday came exactly one week after the Dow lost 778 points, its biggest closing loss in terms of points. On that day, the House voted down an earlier bailout package that had appeared to be a safe bet to pass.

The swings in the Dow on Monday also marked the beginning a fourth week of tumult in the markets. Triple-digit Dow swings have been commonplace since mid-September, when investment house Lehman Brothers went bankrupt and the government stepped in to bail out insurer American International Group.

But even with the bailout package firmly in place — a plan under which the federal government will buy bad mortgage-related assets off the books of banks — investors remain worried that banks are too fearful to lend and are cutting off air to the economy.

Over the weekend, governments across Europe rushed to prop up failing banks, while the governments of Germany, Ireland and Greece also said they would guarantee bank deposits. U.S. investors appeared worried the bailout would not be enough to jump-start the economy. Even other steps, including a Federal Reserve decision to expand a loan program to squeezed banks, didn't help much.

The sharp one-day tumbles over the last two Mondays don't come close to the drops that became black marks on the timeline of Wall Street history. Black Monday, in October 1987, and stock drops that preceded the Great Depression were more than 20 percent. Monday's drop, by comparisons, was less than 8 percent at its worst.

For the day, the Dow lost 3.6 percent. The selling was broad: Little more than 200 stocks finished the day higher on the New York Stock Exchange, while about 3,000 finished lower.