"But how do we know when irrational exuberance has unduly escalated asset values, which then become subject to unexpected and prolonged contractions as they have in Japan over the past decade?"

- Alan Greensham

"Immediately after he said this, the stock market in Tokyo, which was open as he gave this speech, fell sharply, and closed down 3%. Hong Kong fell 3%. Then markets in Frankfurt and London fell 4%. The stock market in the US fell 2% at the open of trade. The strong reaction of the markets to Greenspan's seemingly harmless question was widely noted, and made the term irrational exuberance famous."