Special Report: Coronavirus and Rates | March 5, 2020 As the number of reported cases of the coronavirus around the world has increased, the list of school closings, work interruptions, event cancellations, and other consequences has grown. This decline in economic activity has been brutal for stocks but good for bonds, pushing rates to record low levels. One commonly heard question, though, is why mortgage rates have not fallen as much as government Treasury yields. There are two main reasons. First, mortgage-backed securities (MBS) have prepayment risk while Treasuries do not. When people refinance, their loans are removed from MBS. This makes MBS less valuable to investors relative to Treasuries during periods of declines and more valuable during periods of increases. In other words, mortgage rates rise and fall more slowly than Treasury yields due to the basic properties of prepayment risk. Second, the large mortgage companies which purchase loans and set mortgage rates have the capacity to process only so much business at one time. Currently, there is more demand for loans and refinancings than these firms can handle, so they have less incentive to pass along the lowest possible rates to customers. Here are some actual figures from [...]