Recent theories of economic growth, including Romer (1986), Porter (1989) and Jacobs (1969), have stressed the role of technological spillovers in generating growth. Because such knowledge spillovers are particularly effective in cities, where communication between people is more extensive, data...

We study the determinants of the location of sub-contracted activity in a general equilibrium model of outsourcing and trade. We model outsourcing as an activity that requires search for a partner and relationship-specific investments that are governed by incomplete contracts. The extent of...

We develop a framework for studying trade in vertically and horizontally differentiated products. In our model, consumers with heterogeneous incomes and tastes purchase a homogeneous good as well as making a discrete choice of quality and variety of a differentiated product. The distribution of...

We construct a model of growth based on endogenous technological change in a small, open economy. Entrepreneurs develop new intermediate products whenever the present value of potential profits exceeds the cost of R&D. Diversity of intermediates contributes to total factor productivity in the...

We present a model of shadow banking in which financial intermediaries originate and trade loans, assemble these loans into diversified portfolios, and then finance these portfolios externally with riskless debt. In this model: i) outside investor wealth drives the demand for riskless debt and...

We develop a model with a finite number of multi-product firms that populate an industry together with a continuum of single product firms, and study the dynamics of this industry that arises from investments in the invention of new products. Consistent with the available evidence, the model...

We study a two-country two-sector model of international trade in which one sector produces homogeneous products while the other produces differentiated products. The differentiated-product industry has firm heterogeneity, monopolistic competition, search and matching in its labor market, and...

This paper builds a multi-country, multi-sector general equilibrium model that explains the decision of heterogeneous firms to serve foreign markets either through exports or local subsidiary sales (FDI). These modes of market access involve different relative costs, some of which are sunk while...

We study unanticipated tariffs on imports of intermediate goods in a setting with firm-to-firm supply relationships. Firms that produce differentiated products conduct costly searches for potential input suppliers and negotiate bilateral prices with those that pass a reservation level of match...

The efficiency of common law rules is central to achieving efficient resource allocation in a market economy. While many theories suggest reasons why judge-made law should tend toward efficient rules, the question whether the common law actually does converge in commercial areas has remained...