The growing realization that Katrina will do far more economic damage than ordinary hurricanes held back the stock market today, counterbalancing traders who were buying stocks in hope of making money from the disaster.

Shares of Exxon Mobil Corp. and Caterpillar Inc. were the big gainers in the Dow Jones industrial average, which vacillated wildly, finally closing down 22 points at 10,459.63.

The Standard & Poor's 500 stock index basically broke even, ending the day up a point at 1,221.59. The Nasdaq Stock Market composite index fell four points to 2,147.90.

Energy analysts are recommending oil company stocks because their profits keep getting bigger and bigger as oil prices escalate. Caterpillar? Well, it's gonna take a lot of bulldozers to clean up the Gulf coast.

Wall Street puts its own perverse spin on every event and managed to come up with an argument for buying stocks because of the hurricane.

Fallout from Katrina will slow economic growth, traders reasoned. That will prompt the Federal Reserve to hold back on boosting interest rates. Lower rates will make stocks a more attractive investment.

Washington Fed watchers are not so confident about reading the minds of Alan Greenspan and his colleagues. And there is reason to suspect the economic slowdown would hurt corporate profits -- which directly influence stock prices.

Two important sectors of the economy challenged the idea that there is a silver lining in Katrina's cloud.

Sales of national chain stores already were a little disappointing in August and auto sales were a big disappointment.

The monthly report from big retailers showed August sales growing a little more than 3.5 percent rather than the 4 percent that analysts had been predicting.

Despite all the "employee discount" deals, auto sales were down 13 percent at General Motors and up less than forecast at DaimlerChrysler and Ford, where SUV sales slumped 40 percent.

With Katrina whipping gasoline prices past $3 a gallon, SUVs will look even less appealing -- even though Ford and GM have extended their family discounts for another month.

And the fallout from the storm is expected to darken auto and retail sales for as long as gas prices remain high.