US fixed mortgage rates rose slightly amid mixed housing data on pending home sales and house price gains, according to the Primary Mortgage Market Survey released Wednesday by Freddie Mac. The U.S. mortgage giant said the 30-year fixed-rate mortgage ( FRM) rose to 4.29 percent in the week ending Wednesday from 4.22 percent in the previous week. The 15-year FRM, a popular guide for those looking to refinance, also edged up to 3.30 percent this week from 3.27 percent in the prior week. The five-year Treasury-indexed hybrid adjustable-rate mortgage (ARM) fell to 2.94 percent, and the one-year Treasury-indexed ARM declined to 2.60 percent. "Fixed mortgage rates retraced some of their decline of the prior week as housing data portrayed mixed signals," said Freddie Mac's chief economist Frank Nothaft in a statement. The latest data of the National Association of Realtors on Monday showed a softening in real estate sale near yearend, while the S&P/Case-Shiller House Price index released Tuesday showed house prices in the 20 largest cities increased 13.3 percent annually in September, the highest level since February 2006.