Financial institutions are connected to each other by a series of bilateral transactions. In normal times, institutions' connections may result in efficient risk transfer. But in crises, connections can facilitate contagion - as initial problems lead to chains of defaults and liquidity shortages...

An epidemiologist calculating the risk of a localised epidemic becoming a global pandemic would investigate every possible channel of contagion from the infected region to the rest of the world. Focusing on, say, the incidence of close human contact would underestimate the pandemic risk if the...