According to a piece on Bloomberg, U.S. equities entered this week the cheapest that they had been in 16 years: "The benchmark for American equity is valued at 15.5 times estimated profit, the lowest since January 1991, according to data compiled by Bloomberg."

But does that really mean anything? More importantly, is it indicative of strong returns?

In his great book The only three questions that count, Ken Fisher presents compelling data suggesting that a low price/earnings ratio for the market is not a predictor of strong future returns. In fact, markets tend to perform better when they are "overvalued" based on this metric.

Pick up the book to learn about more paradoxes of investing, and learn to think like one of the best investment minds in business today.