MBB Trailed Treasuries by $9,630 on $300,000 in 2020 as Refinancing Homeowners Capped Its Gains

The article fragment says that a $300,000 investor may lose thousands of dollars from differences in returns between mortgage bonds and Treasuries during a falling-rate environment. It does not provide the return gap, time period, or the reason for the difference; the text ends mid-sentence.