Gartner (NYSE:IT) has outperformed the market over the past 15 years by 12.96% on an annualized basis producing an average annual return of 24.83%. Currently, Gartner has a market capitalization of $40.63 billion. Buying $100 In IT: If an investor had bought $100 of IT stock 15 years ago, it would be worth $2,677.82 today based on a price of $527.30 for IT at the time of writing. Gartner’s Performance Over Last 15 YearsFinally — what’s the point of all this? The key insight to take from this article is to note how much of a difference compounded returns can make in your cash growth over a per…