We show that jumbo mortgage rates were above conforming rates before the financial crisis, consistent with previous studies, and that the spread between them widened during the crisis. However, the spread turned negative in 2013 and remained so through 2019, with jumbo rates about a quarter percentage point below conforming rates. A rise in the government‐sponsored enterprise (GSE) guarantee fees appears to be the main reason for the change. Increased bank supply of jumbo loans also may have played some role, though the evidence is weak. With the onset of the Covid‐19 pandemic, we estimate that the jumbo‐conforming spread increased enough to move slightly above zero.

中文翻译：

---

巨无霸率低于合格率：什么时候发生？为什么？

我们证明，在金融危机之前，超大抵押贷款利率高于合格利率，这与以前的研究一致，而且在金融危机期间，两者之间的差距扩大了。但是，利差在2013年转为负值，并一直持续到2019年，巨型利率比合格利率低约四分之一。政府赞助企业（GSE）担保费的上涨似乎是这一变化的主要原因。尽管证据不足，但银行增加的巨额贷款供应也可能起到了一定作用。随着Covid-19大流行的爆发，我们估计符合巨型标准的点差增加到足以略微高于零的程度。