I came across the chart above recently. It plots the 10 year return on a rolling basis for the S&P 500 since inception back in 1937. So if you had held the S&P for 10 years, it gives you the return per year. The chart isn't the easiest to read, but it gives a pretty blunt message. If you are in the market for 10 years or more, there is a very good chance you will have a great return on investment. In fact the average 10 year return is 120%. To date the 10 year return is 64%.