We use transaction-level US import data to compare firms from virtually all countries in the world competing in a single destination market. Guided by a simple theoretical framework, we decompose countries' market shares into the contribution of the number of firm-products, their average...

Does economic uncertainty promote the implementation of structural reforms? We answer this question using one of the most exhaustive cross-country panel data set on reforms in six major areas and measuring economic uncertainty with stock market volatility. To address endogeneity concerns, we...

We use transaction-level US import data to compare firms from virtually all countries in the world competing in a single destination market. Guided by a simple theoretical framework, we decompose countries. market shares into the contribution of the number of firm-products, their average...

We use transaction-level data to study changes in the concentration of US imports. Concentration has fallen in the typical industry, while it is stable by industry and country of origin. The fall in concentration is driven by the extensive margin: the number of exporting firm has grown, and the...