Empirical work shows that a large majority of individuals get most of their information from a very small subset of the group, viz., the influencers; moreover, there exist only minor differences between the observable characteristics of the influencers and the others. We refer to these empirical...

We develop a model in which connections between individuals serve as social collateral to enforce informal insurance payments. We show that: (i) The degree of insurance is governed by the expansiveness of the network, measured with the per capita number of connections that groups have with the...

Geography and social links shape economic interactions. In industries, schools, and markets, the entire network determines outcomes. This paper analyzes a large class of games and obtains a striking result. Equilibria depend on a single network measure: the lowest eigenvalue. This paper is the...

This paper argues that the extent of financial contagion exhibits a form of phase transition: as long as the magnitude of negative shocks affecting financial institutions are sufficiently small, a more densely connected financial network (corresponding to a more diversified pattern of interbank...

I develop a general theory of monopoly pricing of networks. Platforms use insulating tariffs to avoid coordination failure, implementing any desired allocation. Profit maximization distorts in the spirit of A. Michael Spence (1975) by internalizing only network externalities to marginal users....

Mobile money allows households in Kenya to spread risk more efficiently. In this paper we show that these efficiencies are achieved through deeper financial integration and expanded informal networks. Active networks are more geographically dispersed and support more reciprocal financial...

We study cascades of failures in a network of interdependent financial organizations: how discontinuous changes in asset values (e.g., defaults and shutdowns) trigger further failures, and how this depends on network structure. Integration (greater dependence on counterparties) and...

Motivated by empirical evidence I uncover on the dynamics of French firms exports, I offer a novel theory of trade frictions. Firms only export into markets where they have a contact. They directly search for new trading partners, but also use their existing network of contacts to remotely...

We study the departure time decisions of commuters traversing a traffic network with the goal of arriving at a common destination at a specified time. There are costs associated with arriving either too early or too late, and with delays experienced at bottlenecks. Our main hypothesis, based on...

We report evidence that Bitnet adoption facilitated increased research collaboration between US universities. However, not all institutions benefited equally. Using panel data from seven top engineering journals, Bitnet connection records, and institution ranking data, we find that middle-tier...