If you bought the S&P 500 at the start of any quarter, what would your return be 10, 20, or 30 years later?
Method: Total returns include reinvested dividends. Built from Robert Shiller's monthly S&P 500 series spliced with Yahoo Finance ^SP500TR for recent data. Each point is a hypothetical lump-sum purchase at quarter-start; the return is measured to the same calendar quarter N years later.
Data availability: The 10-year line ends Q2 2016 (last entry that has a full 10 years of forward data), the 20-year ends Q2 2006, the 30-year ends Q2 1996. Beyond those points, the future hasn't happened yet.