Rational IPO Waves

We argue that the number of firms going public changes over time in response to time variation in market conditions. We develop a model of optimal initial public offering (IPO) timing in which IPO waves are caused by declines in expected market return, increases in expected aggregate profitability, or increases in prior uncertainty about the average future profitability of IPOs. We test and find support for the model's empirical predictions. For example, we find that IPO waves tend to be preceded by high market returns and followed by low market returns. Copyright 2005 by The American Finance Association.