The following chart shows the average month-to-date percentage change in the S&P 500 index by trading day during June from 1990 through 2010. Day 0 represents the May close. It shows that the index during June tends to be about neutral, with a short-lived month-end dip. We have not used data for trading day 22, because many Junes do not have 22 trading days. Also, sample size is only 18-21 for specific trading days, so these results are only mildly suggestive rather than predictive. For 1990-2010, 11 Junes have been winners and 10 losers.