Mortgage application volume leapt to 4.1 percent from the week before on the strength of a boom in refinance applications, according to the Mortgage Bankers Association (MBA).

The trade group released its data in a Weekly Mortgage Applications Survey for the week.

The MBA’s Market Composite Index noted a 4.2-percent increase on a seasonally unadjusted basis from the week before, with 9.3 percent for the Refinance Index and 8.2 percent in declines for the seasonally adjusted Purchase Index.

Figures for the unadjusted Purchase Index meanwhile

declined by 11.8 percent, compared with numbers from the past week. The four-week moving average for the Market Index crept forward by 0.65 percent while it moved forward by 0.69 percent for the Refinance Index.

The MBA said that the refinance share of mortgage activity surged forward by 79.7 percent, up from 76 percent from the week before.

“This is the highest refinance share since this year,” the trade group said, adding that the adjustable-rate mortgage (ARM) share of activity deflated from 5.7 percent to 5.6 percent of total applications last week.

Purchase applications fell in all loan categories over November, as mortgages more than $729,000 leapt forward by 1.9 percent in total applications from last month. Loan applications between $150,000 and $300,000 fell 8.9 percent, with those in the range of $150,000 and $300,000 declining 8.6 percent.

The MBA said that applications for loans between $625,000 and $729,000 fell 20.2 percent.

Contract interest rates for mortgages fell on average, with rates for the 30-year fixed-rate mortgage and loans backed by the Federal Housing Administration hitting rock bottom this year.