IBD research shows that the 600 best-performing stocks between 1952 and 2001 had one thing in common: strong earnings growth. “During bull markets (major market uptrends), I prefer to concentrate on stocks that show powerful earnings gains of 40% to 500% or more,” IBD founder and Chairman William J. O’Neil wrote in “How to Make Money in Stocks.” The “C” in IBD’s CAN SLIM investing system stands for current quarterly earnings.