This paper characterizes strongly stable networks under general threshold contagion. Among other applications, the theory is applied to interbank lending and financial contagion wherein a government can intervene to stop contagion. In the absence of intervention, banks form disjoined clusters to minimize contagion. In the presence of intervention, banks become less concerned with the counterparties of their counterparties, which we dub network hazard. Network hazard allows some banks to become systemically important and gives the network a core-periphery structure. The counterparty risk of a large part of the economy becomes correlated through the core banks’ solvency. Core banks serve as a buffer against contagion when solvent and an amplifier of contagion when insolvent. As such, bailouts create welfare volatility and increase systemic risk via network hazard. It is shown that network hazard is a novel force distinct from moral hazard. Results are historically relevant to the pyramiding of reserves and the establishment of the Federal Reserve.
This paper introduces a simple model of endogenous network formation and systemic risk. In the model, firms form joint ventures called ‘links’ which are subsequently subjected to shocks that are either good or bad. Bad shocks incentivize default. Links yield full benefits only if the counterparty does not subsequently default on the project. Accordingly, defaults triggered by bad shocks render firms insolvent and defaults propagate via links. The model yields three insights. First, stable networks with ex-ante identical agents exhibit a core-periphery structure. Second, an increase in the probability of good shocks increases systemic risk. Third, the network formed critically depends on the correlation between shocks to links. As a consequence, an observer who misconceives the correlation will significantly underestimate the probability of systemwide default.
This paper develops a model to study the formation and regulation of information networks. We analyze a cat and mouse game between a regulator, who sets and enforces a regulatory environment, and agents, who form networks to disseminate and share insider information. For any given regulatory environment, agents adapt by forming networks that are sufficiently complex to circumvent prosecution by regulators. We show that regulatory ambiguity arises as an equilibrium phenomenon – regulators deliberately set broad legal boundaries in order to avoid explicit gaming by agents. As a response, we show that agents form a core-periphery network, with core members acting as conduits of information on behalf of their stakeholders, effectively intermediating all transmissions of information within the network.