Centro de Informacion y Documentacion Cientifica (CINDOC). C/Joaquin Costa, 22. 28002 Madrid. SPAIN / CINDOC - Centro de Informaciòn y Documentaciòn Cientìfica

We investigate the socially optimal design of financial networks, that allows to tackle the trade-off between risk sharing and contagion. We identify conditions on the shock distribution under which full integration or maximal segmentation is optimal. We also show that, under different conditions, the optimal network displays different levels of strength of linkages to other firms or intermediate degrees of segmentation. In the latter case, the individual and social incentives to establish linkages are not necessarily aligned. When firms face heterogeneous distributions of risks, they should optimally form linkages only with firms facing risks of the same kind.

We propose a stylized dynamic model to understand the role of social networks in the phenomenon we call “globalization”. In a nutshell, this term refers to the process by which even agents who are geographically far apart come to interact, thus being able to overcome what would otherwise be a fast saturation of local opportunities. A key feature of our model is that the social network is the main channel through which agents exploit new opportunities. Therefore, only if the social network becomes global (heuristically, it “reaches far in few steps”) can global interaction be steadily sustained. An important insight derived from the model is that, for the social network to turn global, the long-range links required (bridges) cannot endogenously arise unless the matching mechanism displays significant local structure (cohesion). This sheds novel light on the dichotomy between bridging and cohesion that has long played a prominent role in the socio-economic literature. Our analysis also relates the process of globalization to other features of the environment such as the quality of institutions or the arrival rate of fresh ideas. The model is partially studied analytically for a limit scenario with a continuum population and is fully solved numerically for finite-population contexts.

We investigate the socially optimal design of financial networks, that allows to tackle the trade-off between risk sharing and contagion. We identify conditions on the shock distribution under which full integration or maximal segmentation is optimal. We also show that, under different conditions, the optimal network displays different levels of strength of linkages to other firms or intermediate degrees of segmentation. In the latter case, the individual and social incentives to establish linkages are not necessarily aligned. When firms face heterogeneous distributions of risks, they should optimally form linkages only with firms facing risks of the same kind. Received November 8, 2014; editorial decision April 28, 2017 by Editor Itay Goldstein.

We show that bank shocks to firms propagate along the production network with stronger upstream than downstream effects. Our identification relies on (i) administrative datasets from Spain covering supplier-customer transactions and bank loans, (ii) bank credit supply shocks from the global financial crisis, and (iii) a general equilibrium model of a production network with financial frictions, estimated structurally. We find network propagation amplifies the impact of bank shocks on GDP growth by nearly 50 percent. Moreover, bank shocks to firms’ distant suppliers and customers contribute similarly to this aggregate effect as bank shocks to firms’ direct customers and suppliers.

In contexts ranging from public goods provision to information collection, a player's well-being depends on his or her own action as well as on the actions taken by his or her neighbours. We provide a framework to analyse such strategic interactions when neighbourhood structure, modelled in terms of an underlying network of connections, affects payoffs. In our framework, individuals are partially informed about the structure of the social network. The introduction of incomplete information allows us to provide general results characterizing how the network structure, an individual's position within the network, the nature of games (strategic substitutes vs. complements and positive vs. negative externalities) and the level of information shape individual behaviour and payoffs.