The Stock Market Is Getting Dangerously Close to Becoming the Most Expensive It's Ever Been (Dating Back to 1871) -- and History Points to Trouble Ahead

But this time-tested valuation tool can be easily tripped up by shock events and recessions. If corporate profits turn into losses, the P/E ratio won't be of much help. This is where the Shiller P/E Ratio can come in handy. Note: the Shiller P/E is also commonly referred to as the cyclically adjusted P/E Ratio, or CAPE Ratio.Most investors turn to the traditional price-to-earnings (P/E) ratio as the foundation for evaluating a stock. A company's P/E ratio is arrived at by dividing its share price into its t ...