When yields on risky bonds decline toward those on safe assets, it is fair to conclude, he argues, that someone is taking on excessive risk. The problem, then, is how to determine exactly when risk premiums are too low.
这就引出了一个问题：如何确定过度的程度以及如何对策。斯特恩提出应该专注于债券市场的风险溢价。当高风险债券收益率向安全资产下跌靠拢时，他指出，就可以认为有人在过度冒险。于是，问题就变味如何确定风险溢价太低。