5 In December 2015, the Board invited public comment on a proposed policy statement describing the framework  that the Board would use to set the amount of the U.S. CCyB. See Regulation Q—Capital Adequacy of Bank Holding Companies, Savings and Loan Holding Companies, and State Member Banks, 12 C.F.R. pt. 217, app. A (2018).
Regulators have long realised that capital is the backbone of a bank; it absorbs losses and it can prevent bank failures. What the capital base of a bank should be is a grand question. The determination of the right amount of capital has always been a very demanding exercise. Why is it so?