In a sequence of op-eds in the Wall Street Journal, an article in the Atlantic Monthly, and a book, James Glassman and Kevin Hassett of the American Enterprise Institute argue that the stock market is undervalued, possibly by a factor of three or more. Their case is predicated on the assumption that the expected return of equities should equal that of treasury bonds, or equivalently, that equity risk premium is undeserved.
As evidence in support of this view, they borrow from Jeremy Siegel's superb study of the history of U.S. capital markets, which shows that stocks have outperformed bonds over every single 20 year period from 1802 to the present time. Unfortunately, the logic that underlies their argument contains a number of flaws, and it behooves us to explore these flaws in some detail.