The sight of a big, round number gets traders so excited that they go ahead and screw it up right away.
Two weeks after the passing of such a big, round number, the S&P 500 averages a 1% gain and is positive 79% of the time, according to Mr. Gassaway. Three months later, the index averages a 3.6% gain and is positive 89% of the time. When the S&P 500 surpassed 1900 back in May, it rallied for another five straight days and nine of the next 10.
Here’s What Happens After Major Market Milestones [WSJ MoneyBeat blog]