The document compares the stock performance of companies identified as going from "good to great" (GTG) against companies that were already great performers (FOE) over various time periods from 3 to 15 years. It shows that while the already great performing companies significantly outperformed the market (S&P 500) over all time periods, the good to great companies generally underperformed or matched the market, suggesting that what makes companies great is not explained by simply going from good to great.