Not that long ago, Political Calculations mapped the extremes of the calendar year to calendar year performance of the S&P 500 stock market index over 105 years from 1900 through 2004. What Political Calculations didn't do was to find the average rates of return for the S&P 500 index for each given holding period over that interval. So, it was back off to the data mines, and what we found is remarkable: the average nominal rate of return for the S&P 500 is essentially flat for any stock holding period, whether it be 1 year, 50 years or 105 years!
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That's right! With vary little variation, the average of average rates of return for each investment holding period from the beginning of 1900 through the end of 2004 is 7.78%. So, if you're interested in calculating the future of your investment in the S&P 500 based on average annual rates of return, just plug 7.78% into Political Calculations' Investing: Future Value calculator for your results!