So, today is the day. An unlucky day, some would have it (although nobody is quite sure why or when it became so). Black cats, broken mirrors etc.
Theres a branch of financial economics that looks at the effect of superstition on the stock market. It has a somewhat different story to tell about Friday the 13th, which is that the effect is perhaps different. There is a large literature on F13 in health, especially mental health which I dont review here but the papers noted below do reference.
- Lucey, Brian M., Friday the 13th: International Evidence (June 2000). maybe there is REVERSE effect and returns are greater…published as Friday the 13th: International evidence (2001) Applied Economics Letters, 8 (9), pp. 577-579
- Coutts, J.A. Friday the thirteenth and the financial times industrial ordinary shares index 1935-94 (1999) Applied Economics Letters, 6 (1), pp. 35-37. ; there is an effect in the UK but its muted
- Keefe, S and Mohammed, K (2011) The friday the thirteenth effect in stock prices: international evidence using panel data
What is the story? Below we see the SP500 returns by day measured from 1928 to presentM -0.056% T 0.009% W 0.071% Th 0.032% Fri 0.046%
For the 147 instances of Friday the 13th the average return falls to 0.011%, still positive but statistically different from both the average daily return of 0.02% and especially from the normal friday return.