A market anomaly that arises when the market price of an asset (stocks, real estate, etc) begins to divert from its intrinsic value (fundamental value). In a bubble, asset prices increase quickly to exaggerated levels. This may occur gradually or quite quickly but the bubble bursts rapidly as the market returns back to its normal levels, or even drop below its fundamental value. A bubble can occur within a particular industry, sector, or the broader market.

A bubble is also known as a speculative bubble.