Jumbo rates below conforming rates: When did this happen and why?

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.