Since 1950, the S&P 500 has gained an average of 1.3%% and the Dow gained 2.2% during the seven-day period in which the rally takes place, and it's gained in 34 of the past 45 years.

Santa Claus rally performance over the years

The Dow rose 77% in the years since the index was created in 1896, and produced an average gain of 1.5%. Over 126 years, the Dow has risen 56%. 

Potential for a stronger Santa Claus Rally this year

Also encouraging is that this tendency is stronger in years, like this year, in which the stock market lost ground year-to-date until Christmas. On average across all such years since 1896, the Dow from Christmas until the second day of January gained 2.2%. 

Thank you Santa :)

So, please, let’s not take Santa’s good name in vain. Besides giving presents to children, he is responsible for the stock market’s Christmas-New Year performance. History suggests that a Santa Claus rally won’t arrive until Christmas, just like the big man himself.