Shiller Version 2 for Wk Open 9/14

In 1998, Robert Shiller--the Yale economist and Nobel Prize winner-- formalized that idea in a paper, "Valuation Ratios and the Long-Run Stock Market Outlook" and a book, "Irrational Exuberance." The latter made Shiller something of an economic prophet. In his book, which came out shortly before the dotcom crash, he warned that stocks were overvalued.

What is the CAPE ratio? It describes the price-earnings ratio over 10 years, rather than on a particular date. Called the Shiller P/E, it is calculated by dividing the price of a stock by its average earnings over the past 10 years, adjusted for inflation . It can also be used on an index such as the S&P 500 .