Friday the 13th to Save the Week?

To make a bad week for the market worse, tomorrow is Friday the 13th. But recent history suggests that Friday the 13ths aren't as ominous as some may think -- at least based on the S&P 500's performance. Below is a table highlighting the S&P 500's change on the 31 Friday the 13ths that have occurred over the last 20 years. As shown, the average change on these days has been +0.34%, with positive returns 68% of the time. The average change for the market on all days over the last 20 years has been +0.03%, so +0.34% is pretty significant outperformance. The last Friday the 13th occurred on November 13th, 2009. On that day, the S&P gained 0.57%. In fact, the index has been higher on seven of the last eight Friday the 13ths.