World of Panic Updated: Stocks slide amid fears of global contagion.

No rollercoaster has a ride quite like today's trading in the stock market.

For much of the day, the trip was one way: down. Stocks tumbled in Asia and Europe. When the market opened in the New York, the Dow Jones industrial average quickly shed more than 200 points. By 2 p.m., it was down 800 points. The market appeared to be in a free fall, with investors gripped by fears that the credit crunch had infected the global economy to the point where it was immune from government actions. It was a panic.

In the last hour and a half of trading, however, buyers emerged and the market pared back its losses. The Dow closed down 369.88, or 3.6 percent to below 10,000 for the first time since 2004. The S.&P, 500 ended down 42.38 points, or 3.9 percent, to its lowest level since November 2003.

"It's like a fire,' Emmanuel Soupre, a fund manager at Neuflize OBC Asset Management in Paris,told Bloomberg News. "It's easier to extinguish five minutes after the start. Now we're about an hour into it. We have to act quickly to assure the continuity of the financial system to avoid an irreversible contamination of the entire economy.'

The response confirms that the new U.S. bailout program won't provide immediate relief to the stresses on the global financial system.

On Friday, after the House passed the bailout legislation, stocks quickly tumbled. The measure authorizes the Treasury secretary to spend as much as $700 billion for buying up the illiquid assets on the balance sheets of many U.S. financial institutions.

Skeptics of the bill warned that the plan was flawed from the start, but the frozen credit markets forced legislators into action now instead of waiting until after the election. (For more on the pros and cons of the bailout, see this interactive.)

The response in Europe and Asia indicates that the U.S. effort may be too little, too late. Fear is begetting fear. A more ambitious, globally coordinated response is needed.

Indeed, the global market rout sparked speculation of a coordinated cut in interest rates by the leading central banks. The futures market is pricing in a half-point cut in rates by the Federal Reserve this month.

Over the weekend, Europe's biggest economy, Germany, promised to guarantee private deposits, and Sweden, Austria, and Denmark followed. Ireland offered insurance to deposits last week. The French bank BNP Paribas bought operations of Fortis in an emergency takeover. Iceland halted trading in shares of its banks.