This study examines the impacts of both market scope and market concentration on the export performance of Indonesian manufacturing firms for the period 2008-2012. The main findings are that broader market scope and more concentrated market portfolio generate higher export. In the experiment of heterogeneous impacts, it is found that the return on market concentration is higher for older firms, more experienced exporters, and larger firms. An experiment with alternative performance indicators finds that market concentration takes one year before affecting firm productivity and profitability, while it takes two years before market scope affects firm profitability.