To estimate correctly the effect of variable trade costs on firms’ exports, the gravity equation should control for the number of firms that participate in foreign markets. Due to the absence of these data, previous studies control for this omitted variable using econometric strategies that...

Using data for all exporters, we show that it is a small group of firms that dominate exports in Spain. For example, in 2015 the top 200 firms were responsible for half of Spanish exports. This concentration has not changed substantially over the 1997–2015 period. The dominance of a few firms,...