Behavioral characteristics of IPO underpricing

Earlier studies document positive first-day return for initial public offerings (IPOs), commonly interpreted as underpricing of the issue. The empirical evidence also indicates that IPO underpricing is negatively related to the public float (the fraction of the firm sold to the public). One possible explanation for this relation is that firms allocate a fixed amount of money for underpricing, and set an issue price accordingly - a behavioral characteristic. But, if indeed firms allocate a fixed amount of money to underpricing, then this underpricing should diminish in the public float. Using a sample of IPOs between 1996 and 2008, we provide empirical evidence that indeed the relation between underpricing and the public float is non-linear. Specifically, the higher the public float, the less the decrease of underpricing in the public float. Moreover, in our regression analysis, regressing underpricing on the reciprocal of the public float provides the best fit. As we show, this result is consistent with firms allocating a fixed amount of money for underpricing. This finding is important because it helps predict underpricing and has implications for firms, investors and regulators.