We study the gains from trade in a model with oligopolistic competition, heterogeneous firms and innovation, and provide a formula to decompose the mechanism. The new insight we provide is that market concentration can be a welfare-relevant feature of market power above and beyond markup...

Gravity equations have been used for more than 50 years to estimate ex post the partial effects of trade costs on international trade flows, and the well-known - and traditionally presumed exogenous - "trade-cost elasticity" plays a central role in computing general equilibrium trade-flow and...

We study the gains from trade in an economy with oligopolistic competition, firm heterogeneity, and innovation. Oligopolistic competition together with free entry make markups responsive to firm productivity and trade costs. Lowering trade costs reduces markups on domestic sales but increases...

We study cross-country price differences in the European market for new passenger cars based on detailed pricing and technical data. Car prices in Europe converged until the year 2003, but not thereafter. Within the EU 15 countries the price range of the median model in 2004 was close to 20...

We build a model of tacit collusion between firms that operate in multiple markets to study the effects of trade costs. A key feature of the model is that cartel discipline is endogenous. Thus, markets that appear segmented are strategically linked via the incentive compatibility constraint....

We develop a method to measure the incidence of monopolistic markup distortions in the global economy. Using semi-parametric formulas, we measure how trade modifies the deadweight loss of markups through two channels: (1) trade-induced change in markup dispersion, and (2) international...

We develop a model that combines monopolistic competition on goods markets with skill-type heterogeneity on the labor market to analyze the effects of trade and migration on welfare and inequality. Skill-type heterogeneity and partial specificity to firms' endogenously chosen skill requirements...

We argue that the narrative of variety-induced gains from trade in differentiated goods needs revision. If producing differentiated varieties of a good requires differentiated skills and if the work force is heterogeneous in these skills, then firms are likely to have monopsony power. We show...