As of yesterday, Mortgage News Daily reported: Mortgage Rates Drop to New 14-Month Lows
Mortgage rates dropped convincingly today, bringing them to new long-term lows. The average lender hasn't offered anything lower for more than a year (January 2018). The improvement came on a combination of news headlines, economic data, and the scheduled sale of US 10yr Treasury debt. [30YR FIXED - 4.375% - 4.5%]The graph shows the relationship between the monthly 10 year Treasury Yield and 30 year mortgage rates from the Freddie Mac survey.
emphasis added
To fall to 4% on the Freddie Mac survey, and based on the historical relationship, the Ten Year yield would have to fall to around 2.1%
To increase to 5% (on the Freddie Mac survey), based on the historical relationship, the Ten Year yield would have to increase to about 3.3%.