I build a simple dynamic model of the formation of an international social network of importers and exporters. Firms can only export into markets in which they have a contact. They acquire new contacts both at random, and via their network of existing contacts. This model explains (i) the...

The gravity equation in international trade is one of the most robust empirical finding in economics: bilateral trade between two countries is proportional to size, measured by GDP, and inversely proportional to the geographic distance between them. While the role of size is well understood, the...

I build a model of international trade with liquidity constraints. If firms must pay some entry cost in order to access foreign markets, and if they face liquidity constraints to finance these costs, only those firms that have sufficient liquidity are able to export. A set of firms could...

I develop a novel theory of GATT/WTO negotiations. This theory provides new answers to two prominent questions in the trade policy literature: first, what is the purpose of trade negotiations? And second, what is the role played by the fundamental GATT/WTO principles of reciprocity and...