Mortgage applications declined 2.4% this past week as home purchases fell to a 15-year low, an industry trade group said. The Mortgage Bankers Association's weekly mortgage applications survey – a measure of the number of refinance and purchase applications filed across the U.S. – fell 2.4% from last week on a seasonally adjusted basis, while the refinance index declined 1.7%. The purchase index – a measure of applications filed to acquire new homes – fell 5.7%, reaching the lowest level on file since December 1996. "Another week of volatile markets and rampant uncertainty regarding the economy kept prospective homebuyers on the sidelines, with purchase applications falling to a 15-year low," said Mike Fratantoni, the MBA's vice president of research and economics. "This decline impacted borrowers across the board, with purchase applications for jumbo loans falling by more than 15 percent, and purchase applications for the government housing programs falling by 8.2 percent." The four-week moving average for the seasonally adjusted market index is now up 6.9%, while the four-week moving average for the purchase index is down 2.6%. The average on the refinance index is up 9.9%. The refinance share of all mortgage activity grew to 79.8% from 78.8% last week. Meanwhile, the rate on a 30-year, fixed-rate mortgage increased to 4.39%, up from 4.32% a week ago, while the 15-year, FRM grew from 3.47% to  3.56%. Write to: Kerri Panchuk.