Why is this important? Well, some economists think that the economy is already in a recession. Earlier this month, the Merrill Lynch economist David A. Rosenberg said that recent employment data suggested the economy might have slipped into a recession at the end of last year. If it did, that could turn out to be reasonably good news for the equity markets now.

Keep in mind that in three of the last four recessions, stocks didn’t simply hold steady  they actually gained ground. In the recession from July 1990 to March 1991, for instance, the S.& P. 500 rose 2.5 percent, despite a severe sell-off in the summer of 1990. And in the recession from January to July of 1980, stocks climbed nearly 6 percent.

There is something else to consider. If the economy is already in recession, the Fed will probably have more impetus to cut short-term interest rates to fuel economic activity. And as Nick Raich, director of equity research at the National City Private Client Group in Cleveland, said, “if the Fed is going to get aggressive from here, it could give a boost to stocks later in the year.”

Aggressive rate cuts could also shorten the duration or severity of a slowdown.

In most cases, stocks tend to rebound as the economy emerges from a recession. The S.& P. study found that after 10 of the last 11 recessions, stocks soared in the ensuing six months. On average, the S.& P. index gained 12.1 percent.

If you measure the market’s performance from recession lows, rebounds are even more compelling. Ned Davis Research looked at the last 10 recessions and found that stocks rose 24 percent, on average, in the six months after hitting a recession low. That is why Tim Hayes, chief investment strategist at Ned Davis, said that while a recession could continue to pressure the stock market, “it could also lead to a great buying opportunity.”

Of course, there are no guarantees that the market will hit bottom in the middle of this slowdown. For instance, after the last recession ended in November 2001, stocks fell 18 percent over the next 12 months.

Still, there are reasons to believe that this will not be a repeat of the bear market of 2000-2.

For starters, Mr. Stovall said, “valuations in the market lead me to believe that this market decline will end up being either a correction or a very light bear market.” Although the price-to-earnings ratio of the S.& P. 500 approached 40 in the final stages of the 2001 recession, the ratio today is only around half of that, indicating that stocks aren’t nearly as pricey.

Moreover, Mr. Raich noted that while profits were likely to take a hit in an actual recession, the weakness in earnings in the third and fourth quarters of 2007 would make for relatively favorable comparisons in the second half of 2008. “So there are some bright spots for the market,” he said. “They’re just being overshadowed right now by all this recession talk.”