After the sharp run-up in stock prices during the bull market of the late 1990s and their subsequent collapse in 2001–2002, the prices of equities as measured by the S&P 500 are once again uncommonly high relative to companies’ current and prospective earnings, causing some to question...

While the prospect for equity values naturally concerns traders and investors, it also is a concern for public policy. Because investors’ wealth depends on the value of corporate equity, the demand for consumption goods can vary with the price of stocks. The valuation of corporations’...