FactSet Senior Earnings Analyst John Butters provides an update of the key metrics for the fourth quarter earnings season for the S&P 500, as we're in the middle of the peak weeks of the earnings season. He then discusses estimate revisions for the S&P 500 for the first quarter. Analysts have been increasing their EPS estimates for S&P 500 companies in aggregate in recent quarters. Has this trend continued in the first quarter?