Usually, investors can count on gains in the Dow Jones Industrial Average the day after a massive selloff. Of the top 10 worst days measured by points, the Dow finished the day higher in nine of those instances. Over the following year, the average has generally shown strong returns.

So far, the Dow's not doing too well today, due to the ongoing worry about economic weakness and expectations for several more quarters of lousy earnings. It should be noted, of course, that only the debacle in October 1987, when the Dow lost 508 points, is among the top 10 one-day percentage losses in the average.