We analyze the role of retail central bank digital currency (CBDC) and reserves when banks exert deposit market power and liquidity transformation entails externalities. Optimal monetary architecture minimizes the social costs of liquidity provision, and optimal monetary policy follows modified Friedman rules. Interest rates on reserves and CBDC should differ. Calibrations robustly suggest that CBDC provides liquidity more efficiently than deposits unless the central bank must refinance banks and this is very costly. Accordingly, the optimal share of CBDC in payments tends to exceed that of deposits.

中文翻译：

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货币和银行业的准备金和 CBDC


我们分析了当银行发挥存款市场力量且流动性转型带来外部性时，零售央行数字货币（CBDC）和准备金的作用。最优货币架构将流动性供给的社会成本最小化，最优货币政策遵循修正的弗里德曼规则。储备金和 CBDC 的利率应该有所不同。校准有力地表明，CBDC 比存款更有效地提供流动性，除非央行必须为银行再融资，而这是非常昂贵的。因此，CBDC 在支付中的最佳份额往往会超过存款。