The last decades were characterized by large increases in world trade, not only in absolute terms, but also in relation to world GDP. This was in large parts caused by increasing exchanges of parts and components between countries as a consequence of international fragmentation of production....

In a North-South model of international trade, we analyze the ways firms procure their inputs in the presence of relationship-specific investments and incomplete contracts. There are heterogenous final-good producers that are located in the North and compete in monopolistic competition....