WASHINGTON, Feb. 6 (Xinhua) -- U.S. fixed mortgage rates continued to drop for the fourth consecutive week, reflecting that weaker housing data are putting downward pressure on the rates, according to the Primary Mortgage Market Survey released by Freddie Mac Thursday.

　　The U.S. mortgage giant said the 30-year fixed-rate mortgage ( FRM) decreased to 4.23 percent in the week ending Thursday from 4. 32 percent in the previous week. The 15-year FRM, a popular guide for those looking to refinance, edged down to 3.33 percent this week from 3.40 percent in the prior week.

　　The five-year Treasury-indexed hybrid adjustable-rate mortgage (ARM) declined to 3.08 percent, and the one-year Treasury-indexed ARM dropped to 2.51 percent.

　　"Mortgage rates fell further this week following the release of weaker housing data," said Freddie Mac's chief economist Frank Nothaft in a statement. "The pending home sales index fell 8.7 percent in December to its lowest level since October 2011. Fixed residential investment negatively contributed to GDP in the fourth quarter for the first time since the third quarter of 2010."

　　"The Institute for Supply Management reported a significant slowing in growth in the manufacturing industry in December than the market consensus forecast," Nothaft added.