The Crisis Goes From Bad to Worse - WSJ.com

Each of the past six recessions has been accompanied by a bear market, with the Standard & Poor's 500-stock index losing, on average, 31%. By that measure, the stock market's current decline -- with the S&P 500 down 43% from its peak -- is already worse than usual.

But stocks lost only 3%, on average, between the start and end dates of those recessions, as defined by the National Bureau of Economic Research. Stocks gained, on average, 6% during the six months after the recessions ended. That suggests buying and holding stocks during a recession is not a bad idea.