Policy-makers have increasingly turned to ‘in-work transfers’ to boost incomes among poorer workers and strengthen work incentives. One attraction of these is that labour supply elasticities are typically greatest at the extensive margin. Because in-work transfers are normally subject to...

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...