It's December and time to deck the halls with boughs of holly, or in CNBC's case, the business channel with chatter of a potential Santa Claus rally and 2019 fortunes.

Santa's performance for the Dow Jones Industrial Average has been fairly reliable over the past five years, with investors rewarded in every year except 2015. But in each of the years when Santa delivered the goods, the market was already trending higher — 2015, the exception, saw a weaker market so Santa stayed away.