Mortgage rates were higher heading into the end of the previous week. To make matters worse, as of Friday afternoon, it didn't look like the average lender had fully accounted for the losses in the bond market.
Bonds dictate interest rate movement. When it comes to mortgages, lenders are paying close attention to trading levels in bond markets, but only change their rate sheet terms if markets move enough. This is known as a "mid-day reprice." Bonds were weak enough for some lenders to reprice on Friday, but most didn't. That meant we were likely to see that bond market weakness reflected in this morning's new rate sheet offerings.
As it happened, bonds staged a somewhat impressive recovery with help from investor concern about global growth. Oftentimes, a big loss in equities markets can send money running to the bond market where it benefits interest rates. This was the case overnight with Chinese stocks leading the way. The strong start in bonds allowed lenders to keep rates roughly unchanged and--in some cases--slightly lower.
All this having been said, the general trend in rates has been slightly higher ever since hitting long-term lows at the beginning of the month. It makes sense to remain defensive when it comes to lock/float decisions until this gently higher trend reverses course.