For what it's worth, Powell isn't alone in cautioning Wall Street, investors, and everyday Americans about potentially inflated asset values. In December 1996, famed Fed Chair Alan Greenspan delivered a speech at the American Enterprise Institute, where he introduced the now well-known phrase "irrational exuberance" to describe a rapid increase in asset valuations during the advent and proliferation of the internet.The emphasis is these six words: "equity prices are fairly highly valued." When the head of t ...