Irrational Exuberance

What Is Irrational Exuberance?

Irrational exuberance is a phrase describing the kind of unfounded investor enthusiasm that can drive asset prices far above levels justified by underlying economic fundamentals. Federal Reserve Chairman Alan Greenspan used the phrase in a 1996 speech questioning whether stock values had become excessive, and it is often retrospectively linked to the speculation of the dot-com era. Economist Robert Shiller later made the term famous with his book Irrational Exuberance, published in March 2000 — coincidentally right around the NASDAQ Composite's peak — which warned that the stock market had become dangerously overvalued.

Why It Matters

The phrase matters because it captures the psychological dimension of speculative bubbles that pure economics can struggle to explain. During the dot-com boom, investors valued companies on website traffic or eyeballs rather than profits, and belief in a transformative New Economy encouraged the sense that old valuation rules no longer applied. When that exuberance faded, the NASDAQ fell about 78% from its 2000 peak and took roughly 15 years to recover. The term endures as shorthand for the moment when optimism detaches prices from value, a warning sign that behavioral economists study to understand how crowds and confidence, not just fundamentals, shape markets.

Test Your Knowledge

Questions on this topic from the EconRecall fact bank:

• What phrase did Federal Reserve Chairman Alan Greenspan use in a 1996 speech that is often retrospectively linked to dot-com era stock speculation?
  "Irrational exuberance"
• Which economist's book "Irrational Exuberance," warning of stock market overvaluation, was published in March 2000, coincidentally right around the NASDAQ's peak?
  Robert Shiller
• Which Fed Chair famously used the phrase "irrational exuberance" to describe financial markets?
  Alan Greenspan