With the stock market continuing to hit new highs almost daily despite the appalling geopolitical disasters and human tragedies unfolding in Ukraine, Gaza, Syria and Iraq, there has been much head-scratching about the baffling indifference among investors. Many economists and analysts see this apparent complacency as a symptom of a deeper malaise: an “irrational exuberance” that has pushed stock prices to absurdly overvalued levels.
The most celebrated proponent of this view is Robert Shiller, the Nobel Prize-winning, Yale University economist who is often credited with predicting both the 2000 stock market crash and the bursting of the U.S. housing bubble. Shiller may or may not have deserved a Nobel Prize for his academic work on behavioral economics but as a practical guide to investing, his approach has been thoroughly refuted by real-world experience.
Shiller’s status as an investment guru owes much to the timing of his book “Irrational Exuberance,” published just days before the collapse of Internet and technology stocks in March 2000. What is less widely advertised, however, is that for decades, both before and after that predictive triumph, the stock market strategy implied by his analysis has turned out to be plain wrong.
Shiller’s argument that stock prices have been inflated to irrational levels is centered on a statistic called the cyclical adjusted price-earnings ratio, or the Shiller price-earnings ratio. Conventional price-earnings ratios divide the current level of share prices by the earnings estimated by analysts for the year ahead.
This ratio for the Standard & Poor’s 500 is now around 17. On this basis many conventional analysts, including Federal Reserve economists, conclude that U.S. stock prices are reasonably valued. A price-earnings ratio of 17 implies that if companies can sustain this level of profitability, they will provide investors with annual earnings of one-17th, or 5.9 percent, which compares favorably with long-term interest rates on government bonds of around 1 percent, after adjusting for inflation.