The authors construct a model of a dynamic economy in which lenders cannot force borrowers to repay their debts unless the debts are secured. In such an economy, durable assets play a dual role: not only are they factors of production but they also serve as collateral for loans. The dynamic...

We analyze a general equilibrium model with search frictions and differentiated commodities. Because of the many differentiated commodities, barter is difficult because it requires a double coincidence of wants, and this provides a medium of exchange role for fiat money. We prove the existence...

We extend the analysis of Kiyotaki and Wright, who study an economy in which the different commodities that serve as media of exchange are determined endogenously. Kiyotaki and Wright consider only symmetric, steady-state, pure-strategy equilibria, and find that for some parameter values no such...

We develop a model of gross job and worker flows and use it to study how the wages, permanent incomes, and employment status of individual workers evolve over time. Our model helps explain various features of labor markets, such as the amount of worker turnover in excess of job reallocation, the...

The authors analyze economies in which individuals specialize in consumption and production and meet randomly over time in a way that implies that trade must be bilateral and quid pro quo. Nash equilibria in trading strategies are characterized. Certain goods emerge endogenously as media of...

We develop an equilibrium search model that incorporates job-to-job transitions, exhibits instances of replacement hiring, and conceptually distinguishes between job and worker flows. We propose a notion of competitive equilibrium for random-matching environments and study the extent to which it...

We develop an analytically tractable Phillips curve based on state-dependent pricing. We consider a local approximation around a zero inflation steady state and introduce infrequent idiosyncratic shocks. The resulting Phillips curve is a simple variant of the conventional time-dependent Calvo...

A number of authors have argued that the conventional model of unemployment dynamics due to Mortensen and Pissarides has difficulty accounting for the relatively volatile behavior of labor market activity over the business cycle. We address this issue by modifying the Mortensen-Pissarides...