We derive a simple equation for the welfare gains from trade when tariffs are liberalized or iceberg trade costs fall. Covering various one-sector trade models that may or may not feature extensive margins and imperfect competition, we generalize the analysis of Arkolakis, Costinot and...

This paper challenges the common assumption of market segmentation in international trade. To analyze export entry and pricing decisions of firms in integrated vs. segmented markets, we develop a novel tractable approach based on stochastic export costs that allows us to compare firm-level and...

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...