The current bull market is one of the longest in history. The extended duration certainly makes it difficult to find slam-dunk buying opportunities at bargain prices, which is supported by the fact that the market looks expensive by many metrics. In fact, the Shiller price-to-earnings (PE) ratio, or the cyclically adjusted PE ratio, of the S&P 500 is higher today than at any other time in history, save for the run-up to the dot-com bubble burst in 2000.