By JLP | September 18, 2009
Okay, here is an updated version of a post I did a couple of years ago where I took the returns for the S&P and analyzed them by various rolling-periods (5-years, 10-years, and 20-years). Today, I want to look at 20-year rolling-period returns. Check out the graphic I prepared (you can click on the graphic to see a larger version):
It’s incredible just how skewed results can become due to one bad or good year. Notice how 2008′s -37% return dropped the average annual return over the last 20 years to 5.60% (note that these returns include inflation).
Here are some other interesting findings:
• 0 The number of 20-year periods that had a negative return.
• 64 The number of periods that had a positive return.
• 403.02% The average TOTAL return of all the 20-year periods.
• $50,302 The average amount (after inflation) that $10,000 grew to over each 20-year period.
• $130,946 The most $10,000 would have grown to during a 20-year period.
• $11,082 The smallest amount that $10,000 would have become over each 20-year period.