Welcome to Morning Brief presented by Robin Hood, the home to commission free trading. I'm Yahoo Finance executive editor Brian Sazy. Let's fire up three things you need to know on this day after Christmas trading session.First up, I remain on Santa Claus rally watch as the Grinch may not rip this from the mouths of the bulls. Stocks flirting with fresh records as the Santa rally period is now underway. A little news you can use here.Stocks have enjoyed a Santa Claus rally in nearly 80% of the last 50 years ...