Two of the most robust results from dynamic competitive models of industrial organization suggest that higher-sunk-cost industries should exhibit higher intertemporal variability in the market value of their firms and lower intertemporal variability in the size of their industries. These predictions have done well empirically. This paper argues on theoretical and empirical grounds that depreciation generates countervailing effects.

Lockups are agreements made by insiders of stock-issuing firms to abstain from selling shares for a specified period of time after the issue. Brav and Gompers (2003) suggest that lockups are a bonding solution to a moral hazard problem and not a signaling solution to an adverse selection problem. We challenge this conclusion theoretically and empirically. In our model, insiders of good firms signal by putting and keeping (locking up) their money where their mouths are. Our model yields two comparative statics: lockups should be shorter when a firm is i) more transparent and/or ii) more risky. Using a sample of 4,013 initial public offerings and 3,279 seasoned equity offerings between 1988 and 1999, we find empirical support for our theoretical predictions.

We examine the sex differences in the pay of school teachers in Missouri. In Missouri school districts, pay is determined by a salary schedule that maps teaching experience and education level of an individual to a salary level. In spite of this apparently mechanical rule for determining pay, female teachers earn less than male teachers, after controlling for experience and education. We explore how such a difference could arise from differential job mobility and find some evidence to support this idea. However, within district differences in pay are a more important source of differences in pay between men and women.