The number of mortgage applications last week rose 2.7% on a seasonally adjusted basis from the prior week, once again pushed up by refinancing activity that remains at the highest level since May 2009, according to the Mortgage Bankers Association. The MBA said the index rose 2.3% on an unadjusted basis. The seasonally adjusted refinance index climbed 2.8% for the week ended Aug. 27 from the week earlier. The purchase index rose 1.8% for the week. "Refinancing activity picked up again last week, reaching new 15-month highs, as borrowers took advantage of even lower mortgage rates," MBA vice president of research and economics Michael Fratantoni said. "The drop in mortgage rates was in line with Treasury rates as the latest data continue to show weak economic growth and an exceptionally weak housing market." In four-week moving averages, the seasonally adjusted market index is up 5.2%, the purchase index is down 0.2% and the refinance index is up 6.3%. Fratantoni said the sharp decline in the firm's purchase application index in May foreshadowed the drops in home sales the following two months, and he doesn't expect sales activity to increase for August or September. Refinancings accounted for 82.9% of all mortgage applications last week, up from 82.4% the week prior and at the highest level since January 2009. MBA said the unadjusted purchase index decreased 0.4% from the prior week and is 37% lower than the year ago. Interest rates for 30-year fixed and 15-year fixed mortgages continue descending to the lowest rates ever recorded by the MBA survey. The average rate for the 30-year fell to 4.43% from 4.55% and the 15-year decreased to 3.88% from 3.91%. The Mortgage Maxx weekly index, which adjusts data to reflect the number of households applying for a mortgage, showed application activity rose 6.9% last week after dropping 2.4% the week before. Write to Jason Philyaw.