Mortgage applications retreated last week: MBA NEW YORK (Reuters) - Applications for home mortgages retreated last week, giving back some of the previous week's surge as interest rates rose, an industry group said on Wednesday. The Mortgage Bankers Association said its seasonally adjusted index of mortgage application activity, which includes both refinancing and home purchase demand, fell 5 percent in the week ended Jan 20. The index had soared more than 20 percent the previous week. The MBA's seasonally adjusted index of refinancing applications slipped 5.2 percent, while the gauge of loan requests for home purchases was off 5.4 percent. The refinance share of total mortgage activity decreased to 81.3 percent of applications from 82.2 percent. Fixed 30-year mortgage rates averaged 4.11 percent, up 5 basis points from 4.06 percent.