Predictable Long-run Stock Market Returns?
February 20, 2013
Are there exploitable long-term cycles in U.S. stock market returns? In the January 2013 update of his paper entitled “Secular Mean Reversion and Long-Run Predictability of the Stock Market”, Valeriy Zakamulin explores mean reversion of the S&P Composite Index over intervals ranging from two to 40 years. He then runs an out-of-sample horse race using inception-to-date data to compare three regression-based models for forecasting long-term stock market returns: (1) mean reversion over the dynamically optimal horizon; (2) the random walk (future mean return equals (evolving) historical mean return); and, (3) valuation based on Robert Shiller’s cyclically adjusted price-to-earnings ratio (P/E10). Using real (Consumer Price Index-adjusted) S&P Composite Index total annual returns and earnings over the period 1871 through 2011 (141 years), he finds that: (more…)