Demand for mortgage refinancing hit a 15-month high in the week ending Aug 13, according to The Mortgage Bankers Association.

The MBA's Refinance Index rose 17.1% from a year earlier, and is now at its highest since May 2009, the MBA said in a statement. The refinance share of total mortgage applications rose to 81.4%, the highest since January 2009.

Demand for refinancing loans helped drive The Market Composite Index up by 13% on a seasonally adjusted basis from a week earlier. The index is a measure of total mortgage loan applications.

The average contract interest rate for 30-year fixed-rate mortgages was 4.6%, up from 4.57% a week earlier.