A better option would be to implement time-varying, pro-cyclical floors, forcing banks to hold more capital during housing booms. And, whereas a single, fixed floor might push banks toward riskier loans that offer higher returns for the same amount of capital, a dynamic system would allow lower floors for the lowest-risk mortgages and require higher floors for riskier loans.
尽管这些措施值得欢迎，但步子仍然迈得太小；更重要的是，它们缺少灵活性。更好的办法是实施随时间变化的顺周期下限，强迫银行在房地产繁荣期持有更多资本。此外，一刀切的固定下限可能促使银行将同等资本用于风险更大、回报也更大的贷款；而动态系统允许降低风险最低的按揭贷款的下限，而对风险较大的贷款要求较高的下限。