They have a formula that defines how much Tier I and Tier II capital a bank has to hold and the amount depends on the risk class of their investments.

有一个公式可以计算出,一个银行到底需要持有多少一级和二级资本,其数量取决于他们投资项目的风险等级

耶鲁公开课 - 金融市场课程节选