This article highlights a novel channel through which the level of deposits matters for bank fragility and efficiency. We augment a global-game model of bank runs with a consumption-saving choice that determines deposit size in the initial period. We derive two key results. First, depositors’ incentives to run increase with the amount of savings held as bank deposits. Second, a saving externality emerges because individual depositors fail to internalize the impact of their deposit decisions on the likelihood of a bank run. This leads to depositors’ over-saving and inefficient bank liquidity provision, as well as excessive bank fragility. Finally, we characterize the optimal policy to implement the efficient allocation.

We develop a growth model with banks and markets to reconcile the observed decreasing trend in the relative liquidity of many financial systems around the world with the increasing household participation in direct market trades. At low levels of economic development, the presence of fixed entry costs prevents the agents from accessing the market, and pushes them towards the banks, which provide high relative liquidity. We characterize the threshold after which the agents are rich enough to access the market, where the relative liquidity is lower, and show that the relative liquidity of the whole financial system (banks and markets) drops because of the increasing market participation. We provide some evidence consistent with this theoretical prediction: a one-unit increase in an index of securities market liberalization leads to a drop in the relative liquidity of between 17 and 27 per cent.