Freddie Mac released its weekly update on national mortgage rates on Thursday morning, showing a mixed bag that included a slight drop in the average rate for 30-year fixed-rate mortgages and a spike in the rate for 5/1 adjustable-rate mortgages.

Fixed-rate mortgages (FRMs) moved in opposing directions over the past week, with 30-year FRMs dropping two basis points to land at 4.51%, while 15-year FRMs added a single b.p. to reach 3.56%.

A year ago, 30-year FRMs were averaging 3.40% and 15-year FRMs averaged 2.66%.

Among adjustable-rate mortgages (ARMs), 5/1 ARMs spiked sharply over the past week -- up 10 basis points to 3.15%. In contrast, shorter one-year ARMs held steady at 2.56% for the third week in a row.

A year ago, 5-year ARMs averaged 2.67% while one-year ARMs averaged 2.60%.

Commenting in a statement, Frank Nothaft, Freddie Mac's vice president and chief economist, said rates were "little changed amid a week of light economic reports."

There was one private-sector jobs report -- from ADP -- which showed 238,000 jobs added in December, and this was a better number than had been expected. Counteracting this positive news was a report from the Institute for Supply Management that suggested growth in America's non-manufacturing industry is slowing down.