The S&P 500 Index (SPX) has historically outperformed on Friday the 13th, but things have changed in the last decade
While today's broad-market sell-off may be scary enough for some, those who are superstitious consider Friday the 13th -- tomorrow's date, for those who haven't been keeping track -- to be among the unluckiest days of the year. But superstition rarely plays a part in the performance of stocks. Or does it? In the tables below, Schaeffer's Senior Quantitative Analyst Rocky White explored how the S&P 500 Index (SPX) has historically performed on Friday the 13th, compared to anytime returns.

As you can see, the data going back to 1950 shows that Friday the 13th has historically been a boon for stocks. In fact, the SPX has averaged a gain of 0.07% for the day, compared to an average daily gain of 0.05% anytime. Plus, the index has seen a positive return 57.5% of the time on Friday the 13th -- greater than the 53.6% positive rate for anytime returns. But has this pattern of outperformance changed over time? In the next table, White looked only at data back to 2007:

The difference in results is rather astounding. In the past 10 years, the SPX has notably underperformed on Friday the 13th, yielding a positive return just 50% of the time, and averaging a loss of 0.02%. That's in contrast with the S&P's anytime return of 0.03%, and positive 54% of the time, over the same period.
Need more proof that tomorrow could be a down day? The past three consecutive occurrences of Friday the 13th all saw losses, and reasonably significant ones, at that. Per the table below, these three unlucky days averaged a loss of 0.9 % -- not a great omen for tomorrow.

Don't feel too comfortable once tomorrow passes, either -- this year will have another Friday the 13th in October. Still, for traders trying to spy out a trading opportunity for tomorrow's peculiar date, check out this list of historically
outperforming ETFs. Plus, stay tuned for an upcoming article identifying the best and worst SPX stocks on Friday the 13th in the past decade.
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