Since retiring from the Federal Reserve in mid-2016, our friend Jamie McAndrews has been very busy. Unlike most of us, he is putting his ideas into action: in 2015, he and a number of his colleagues, proposed the creation of segregated balance accounts (SBAs). As they write, “SBAs are accounts that a bank or depository institution (DI) could establish at its Federal Reserve Bank using funds borrowed from a lender.” Their proposal is that a bank would offer a special account that it is fully collateralized by a deposit at the Federal Reserve. Furthermore, the SBA deposits would be remunerated at the interest rate the Fed pays on excess reserves (the IOER), minus a small fee for the bank.

We have no expertise whatsoever in determining whether the Fed has legal grounds for denying TNB a Master Account—the subject of the court case in the opening quote. But we do have concerns about SBAs and narrow banks: we worry that they would shrink the supply of credit to the private sector and aggravate financial instability during periods of banking stress. Compared to what may be large costs, we suspect that the benefits would be small….