FactSet Senior Earnings Analyst John Butters provides a preview of the key metrics for the fourth quarter earnings season for the S&P 500 which is about four weeks away. He then discusses expectations for the S&P 500 for 2021. Specifically, he looks at expectations for earnings growth, revenue growth, and profit margins, as well as analysts' ratings on the S&P 500 as we head into the start of a new year.