We provide a theory of trading through intermediaries in over-the-counter markets. The role of intermediaries is to sustain trade. In our model, traders are connected through an informational network. Agents observe their neighbors’ actions and can trade with their counterparty in a given period through a path of intermediaries in the network. Nevertheless, agents can renege on their obligations. We show that trading through an informational network is essential to support trade when agents infrequently meet the same counteparty. However, intermediaries must receive fees to implement trades. Concentrated intermediation, as represented by a star network, is both constrained efficient and stable when agents incur linking costs. The center agent in a star can receive higher fees as well.

Drawing on a novel database of the 401(k) plans of 296 firms, we examine the international equity allocations of 3.8 million individuals over the 2005–2011 period. We find enormous cross-individual variation, ranging from zero to more than 75%, and strong cohort effects, with younger cohorts investing more internationally than older ones and each cohort investing more internationally over time. Access to financial advice, lower fees, and more international fund choices are associated with higher international allocations, suggesting a role for plan design and policy. Education, financial literacy, and the fraction of foreign-born population in the ZIP code also have positive effects on international diversification, consistent with explanations based on familiarity bias and information barriers.