We develop a model of liquidity shortages that incorporates a general equilibrium feature of liquidity: when banks hold more liquidity, other agents in the economy hold less of it and will supply less in times of crisis. We show that the private holdings of liquidity at banks are inefficient, with the direction of the bias being determined by the characteristics of the suppliers of liquidity to banks. Minimum liquidity requirements for banks may reduce welfare; in such cases interest rate policies that stimulate the ex-post supply of liquidity can restore efficiency. Overall, our results show that optimal liquidity policies critically depend on a financial institution’s (marginal) source of liquidity and will hence differ across institutions of different types.

我们建立了一个流动性短缺模型，该模型纳入了流动性的一般均衡特征：当银行持有更多的流动性时，经济中的其他主体持有的流动性就会减少，并且在危机时期的供应量也会减少。我们表明，私人持有的银行流动性效率低下，偏向的方向取决于银行的流动性供应商的特征。银行的最低流动资金要求可能会减少福利；在这种情况下，刺激事后流动性供应的利率政策可以恢复效率。总体而言，我们的结果表明，最佳流动性政策主要取决于金融机构的（边际）流动性来源，因此，不同类型的机构之间会有所不同。