Federal Reserve Chairperson Janet Yellen was recently asked if she was comfortable with the Dow approaching 20,000. She replied “Rates of return in the stock market relative to – remember that the level of interest rates is low – and taking that into account. I believe it’s fair to say that they remain within normal ranges.”
Janet Yellen is not the first person to claim that high stock market valuations are normal when interest rates are low. In theory owners of stocks expect a risk premium over the risk-free rate available to holders of government bonds. When the risk-free rate is itself zero, the yield on equities will be nothing more than the risk premium, and a low yield on equities translates into a high price earnings ratio.