Mortgage applications continue to swing drastically, bouncing back up last week with a double-digit increase compared to a double-digit decrease the prior week. The Mortgage Bankers Association said its market composite index rose 11.3% on a seasonally adjusted basis for the week ended Jan. 28. On an unadjusted basis, the index climbed 13.2% last week. The index fell nearly 13% the prior week, which didn’t include an adjustment for the Martin Luther King Jr. holiday. “Applications increased this week relative to the holiday week,” said Michael Fratantoni, MBA vice president of research and economics. “Looking over the past two weeks, purchase applications are flat, and refinance applications are down about five percent.” Refinancing activity rose 11.7% last week after sliding to the lowest point in 12 months the prior week. The purchase index increased 9.5%. The unadjusted purchase increased 16.7% from the prior week but is 21.4% lower than a year earlier. In four-week moving averages, the market index is up 1%, with the purchase index down 1.5% and the refinance index up 1.7%. The level of refinancings continues to drop and loans accounted for 69.3% of all mortgage applications last week, which is the lowest level since the middle of May. Refinancing accounted for 70.3% of all applications the previous week. The MBA said the average interest rate for a 30-year fixed mortgage inched up to 4.81% last week from 4.80% the prior week. The average rate for a 15-year fixed mortgage also rose slightly to 4.13% from 4.12%. Write to Jason Philyaw.