A theory of bank liquidity requirements

We develop a general equilibrium theory of financial intermediation and its implications for liquidity regulation. The model is built around an agency problem arising from leveraged intermediation: banks finance loan origination with deposits and face moral hazard in risk management, while holding cash mitigates these incentives at the cost of foregone investment returns. Liquidity demand therefore emerges endogenously from incentive considerations rather than from exposure to exogenous funding shocks. In equilibrium, financial experts choose between allocating equity to the banking sector relative to the non-bank financial sector that can provide ex-post liquidity by buying bank assets. Asset prices are determined endogenously in liquidation states, linking banks’ ex ante liquidity choices to market liquidity and the allocation of intermediation across sectors. Comparing the decentralized equilibrium to a planner’s allocation, we show that liquidity regulation mandating higher cash holdings improves incentives within banks but is not sufficient to implement the efficient allocation. In particular, it leads to an inefficiently large banking sector that free-rides on liquidity provision by non-bank investors. Implementing the planner’s allocation requires a second policy instrument, such as limits on bank size or subsidies to equity-financed liquidity provision outside the banking sector. JEL Classification: G21, G28, D82, D6