With fear paralyzing the global money markets, the world's leading central banks are riding to the rescue, announcing that they will pump in huge amounts of U.S. dollars into the system.

More than $180 billion will be made available to banks for short-term financing, under a coordinated effort among the Federal Reserve, the European Central Bank, the Bank of Japan, the Bank of England, the Bank of Canada, and the Swiss National Bank.

The Fed also says that it's taking steps in order to be better able to transfer dollars to foreign banks. While the crisis of confidence has gripped nearly all money markets, the stress in dollar-denominated markets has been particularly acute in recent days.

In a joint statement, the banks said: "These measures, together with other actions taken in the last few days by individual central banks, are designed to improve the liquidity conditions in global financial markets. The central banks continue to work together closely and will take appropriate steps to address the ongoing pressures."

The tidal wave of money quickly steadied markets around the world. Stock markets in Asia and then Europe turned higher.

More important, the overnight interest rates that banks charge each other, which had spiked higher in recent days—fueling the crisis—retreated today.

The question is how long can the market stay calm. 

The fear that another big financial institution will collapse is still very much with us, as is the fear that there is more toxic debt in the system to be discovered—a realization illustrated by the announcement on Tuesday by a "safe" large money-market fund that investors might lose money because of a write-down of Lehman Brothers securities that were held by the fund.

There is a reason for the fear in the market, even if that fear is now feeding on itself.

Another reason not to be too encouraged by the joint central bank action is that the central banks have shown themselves to be largely impotent in wresting with the 14-month crisis.

"Markets know that central banks don't own a magic bullet, otherwise they would have used it already," Sean Callow, currency strategist at investment firm Westpac, told the BBC.

John Jansen on the Across the Curve blog says: "Volatility will not end suddenly but will diminish over time. So expect the same forces that have assaulted the markets recently to buffet the markets once again today. The winds of change blow slowly, and it is too soon to expect the market to turn placid."