This from one of my favorite bloggers who has been investing for over 40 years, StockChartist.
Even though it feels frustration looking at a chart that stretches years, I find it worthwhile to periodically update the "Regression to the Mean" graph because it helps keep our expectations in check. Whether today we are bearish or bullish about prospects for the market's near-term future, this "Regression to the Mean" will help moderate our views and help contain them within the realm of possibilities.
First, some background is necessary and warranted. I had accumulated monthly statistics on the S&P 500 Index going back to 1939 while working on my book, Run with the Herd, during the Financial Crisis Crash in 2007-08. What I had discovered was that when viewed within the broad sweep of history, the market had risen risen at a 7.5% rate, through bull market and bear, war and peace, economic boom and bust. In order to be able to make that statement, I added a boundary 44% on either side of
