Traders' superstitious fears about Friday the 13th are based somewhat on history.
Back to 1980, there have been five Friday 13ths in March and they have been pretty negative for the Dow Jones Industrial Average and the S&P 500 Index, according to Kensho, a quantitative analysis tool used by hedge funds.
On those days, the Dow and S&P 500 have been positive just 2 out of 5 times, or 40 percent of the time, with an average return of 0.03 percent for the Dow and 0.12 percent for the S&P.
Looking at all the Friday the 13ths throughout the year going back to 1990, the markets do a little better, but not great.
The S&P 500 is positive 63 percent of the time with an average return of 0.24 percent on Friday 13ths in the last 25 years.The Dow is positive 67 percent of the time with an average return of 0.21 percent.