It was a good run for mortgage rates, relative to the rest of 2018, but after spending 3 days in a row with mild-to-moderate improvements, rates quickly snapped back to multi-year highs today. The general trend in 2018 as well as the general level of volatility deserve some of the credit. The bonds that underlie mortgage rate pricing actually aren't quite back to last week's levels. Lenders are simply quicker to adjust things for the worse when the trend has been unfriendly and when the prices of those underlying bonds have been jumping around as much as they have.
The other part of the credit goes to the market's interpretation of comments made by new Federal Reserve Chair Jerome Powell, who gave his first semi-annual congressional testimony today. Powell didn't do or say anything wrong. In fact, he did a great job conveying what recent speeches and policy documents suggest we already know about the Fed's policy stance.
The only issue was one of his comments was open to the interpretation of pointing toward an additional rate hike in 2018. Many market participants were already planning on that rate hike, but the prevailing view was for a slightly slower pace. After the Powell comment (he simply said he things the economic outlook is stronger now than he did in December), some of the investors in the "prevailing view" camp shifted their rate hike outlook to the "additional hike in 2018" camp. That was enough for mid-day bond market weakness and widespread lender adjustments to higher rates in the middle of the day.