We use detailed data on exporters from Costa Rica, Ecuador and Uruguay as well as on their buyers to show that: aggregate exports are disproportionally driven by few multi-buyers exporters; and each multi-buyer exporter's foreign sales of any product are in turn accounted for by few dominant...

We document how demand shocks in export markets lead French multi-product exporters to re-allocate the mix of products sold in those destinations. In response to positive demand shocks, those French firms skew their export sales towards their best performing products; and also extend the range...