What are stocks worth?
It's a loaded question. Any stock can appear overvalued or undervalued depending on which valuation metrics you use.
The same logic applies to the broader stock market. Right now, some think the market is undervalued as the U.S. economy appears poised for a solid long-term upturn. Others think we're headed for a market downturn as the Federal Reserve winds down its aggressive liquidity-boosting efforts.
Yet by at least one measure, which happens to be a favorite market gauge for Warren Buffett, the market has just become...