Measured by the cyclically adjusted price-earnings ratio, the current valuation of the S&P 500 index is 40.8 times. This indicator was promoted by Yale University economist Robert Schiller, who won the Nobel Prize in Economics in 2013 for his research on asset prices. In Schiller's 145-year data record, the only time the indicator broke through the 40 mark was a few years before and after the internet bubble peaked in early 2000.

Measured by the cyclically adjusted price-earnings ratio, the current valuation of the S&P 500 index is 40.8 times. This indicator was promoted by Yale University economist Robert Schiller, who won the Nobel Prize in Economics in 2013 for his research on asset prices. In Schiller's 145-year data record, the only time the indicator broke through the 40 mark was a few years before and after the internet bubble peaked in early 2000.