Can we detect a share price bubble at present?
A rational bubble is a deviation from the fundamental level of share prices that rise, in anticipation, in line with the nominal interest rate plus the (theoretical) equity risk premium . The fundamental level is equal to the discounted sum of future dividends. The presence of a rational bubble is reflected in an abnormal fall in the (calculated) equity risk premium. There was a rational share price bubble: In the United States from 1995 to 2001, but not today, as the equity risk premium is now only slightly lower than its historical average; In the euro zone from 1995 to 2001, but not today, as the equity risk premium is now slightly higher than its historical average.