Global Firms
研究了过去二十年国际贸易研究从国家和行业转向企业的变化，提出了一个允许企业拥有大市场份额并同时决定生产地点、出口市场、投入来源等的新理论框架，并用美国数据验证了这些决策之间的相互依赖和互补性。
Research in international trade has changed dramatically over the last twenty years, as attention has shifted from countries and industries towards the firms actually engaged in international trade. The now-standard heterogeneous firm model posits measure-zero firms that compete under monopolistic competition and decide whether to export to foreign markets. However, much of international trade is dominated by a few “global firms,” which participate in the international economy along multiple margins and account for substantial shares of aggregate trade. We develop a new theoretical framework that allows firms to have large market shares and decide simultaneously on the set of production locations, export markets, input sources, products to export, and inputs to import. Using US firm and trade transactions data, we provide strong evidence in support of this framework's main predictions of interdependencies and complementarities between these margins of firm international participation. Global firms participate more intensively along each margin, magnifying the impact of underlying differences in firm characteristics and increasing their shares of aggregate trade.