Recent empirical work indicates that job creation and destruction rates are large, implying significant amounts of job reallocation across firms. This paper builds a general equilibrium model of this reallocation process, calibrates it using data on firm-level dynamics, and evaluates the...

We develop a general model of lending in the presence of endogenous borrowing constraints. Borrowing constraints arise because borrowers face limited liability and debt repayment cannot be perfectly enforced. In the model, the dynamics of debt are closely linked with the dynamics of borrowing...

This paper presents a model of cumulative innovation where firms are heterogeneous in their research ability. We study the optimal reward policy when the quality of the ideas and their subsequent development effort are private information. The optimal assignment of property rights must...

This paper empirically examines the effects of market size on producers' sizes in retail trade industries with many producers. A robust prediction of oligopoly theory is that larger markets are more competitive and have lower price-cost markups. Because producers in more competitive markets must...

Entry restrictions are a common form of regulation in markets and occupations, either as a means of limiting the size of a market or affecting the quality of products or services provided by it. This paper analyzes demand, cost and informational characteristics that affect the impact of this...

We study an optimal patent problem in the spirit of Hopenhayn, et al (2006), but where all innovations arise from two repeated innovators. Following Hopenhayn, et al (2006) we divide patent regimes into those that are exclusive, in the sense that only one firm ever has a claim on the current...

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We compute the model numerically to show various possible outcomes. We show solutions where the model eventually leads to relatively equal rewards, and contrast these cases with ones where the long run has persistent differentials. We compute the average reward as a function of the number of...

We study a multiperiod principal-agent problem with moral hazard in which effort is persistent: the agent is required to exert effort only in the initial period of the contract, and this effort determines the conditional distribution of output in the following periods. We provide a...