Investors always have to make decisions on the basis of imperfect information.
And it's no accident that it tumbled so sharply last week. As of Thursday's Thanksgiving Day break, it stood at 2755, down more than 18 percent since the election and more than 32 percent since Jan. 1. The Dow industrial average was off more than 9 percent for the year, too. Indeed, the only big winner has been the 38 percent gain in the Dow utilities average, made up of the ho-hum stocks to which people flee in times of trouble. The Nasdaq's fall is just one sign of a broader anxiety that has been rippling across global financial markets for most of this year.