CHAPEL HILL, N.C. — I have some advice for you if you pay close attention to those initial reports on how Black Friday or Cyber Monday sales are going:Not only are those initial reports worthless as a leading indicator of how the holiday shopping season will turn out, you might even want to bet that they are downright misleading.
The same reversal pattern emerges if we broaden our focus to include this index’s return over the two post-Thanksgiving trading sessions — encompassing both Black Friday and Cyber Monday. Over those two days, the S&P Retail Select Industry Index rose 2.2%, before proceeding to fall 10.0% from then until the end of 2018.
To be sure, since this index has existed only since 1999, there is not enough data to draw conclusions with great statistical confidence. So, as a double check, I looked at the Dow Jones Industrial Average DJIA, +0.15% for all years since 1975, which is the first year that I was able to determine that the term “Black Friday” began being used.
Even if you don’t want to bet on this contrarian story about overreaction, you at a minimum must conclude that the trading days following Thanksgiving are nothing more than statistical noise.