This paper presents a three-period model to analyze why banks need bank reserves for interbank payments despite the availability of other liquid assets like Treasury securities. The model shows that banks need extra liquidity if they settle bank transfers without the central bank. In this case, each pair of banks sending and receiving bank transfers must determine the terms of settlement between them bilaterally in an over- the-counter transaction. As a result, a receiving bank can charge a sending bank a premium for the settlement of bank transfers, because depositors'demand for timely payments causes a hold-up problem for a sending bank. In light of this result, the large value payment system operated by the central bank can be regarded as an interbank settlement contract to save liquidity. A third party like the central bank must operate this system because a custodian of collateral is necessary to implement the contract. This result implies that bank reserves are not independent liquid assets, but the balances of collateral submitted by banks to participate into a liquidity-saving contract. The optimal contract is the floor system. Whether a private clearing house can replace the central bank depends on the range of collateral it can accept.
Payment Instruments and Collateral in the Interbank Payment System
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