Mortgage refinance applications rose dramatically, according to the Mortgage Bankers Association's (MBA) weekly mortgage applications survey for the week ending Sept. 28.

The MBA's refinance index increased 20% from the previous week, marking its highest point since April 2009. The refinance share of mortgage activity increased to 83% of total applications from 81% the previous week.

The MBA's market composite index increased 16.6% on a seasonally adjusted basis from one week earlier. On an unadjusted basis, the index increased 17% compared with the previous week.  

The seasonally adjusted purchase index increased 4% from one week earlier. The unadjusted purchase index also increased 4% compared with the previous week and was 11% higher than the same week one year ago.