The Dow today, at its high, was up more than 1 percent from yesterday. At its low, it was down more than 1 percent.

It was the first such day in more than four years. The last one was April 9, 2003, another day on which, as today, the bears prevailed at the close. But not for long. The Dow ended that day at 8,197.94. It has not been that low since.

Over the last 20 years, those days have come in spurts. There were 12 such days in 1987, the year of a soaring stock market that ended in a crash, and there were 22 in 2002, the year the market hit bottom after the 2001 recession and the bursting of the technology bubble. But no other year had more than nine.