Mortgage rates fell slightly this week for the third consecutive week in a row. According to a weekly rate survey published Thursday by Freddie Mac (FRE), 30-year fixed-rate mortgages averaged 6.04 percent with .7 point, down slightly from last week’s average of 6.14 percent. This week’s five-year treasury-indexed hybrid ARMs eased to 5.87 percent with an average .6 point from last week’s 5.98 percent, according to Freddie Mac. One-year Treasury-indexed ARMs were no exception to the falling trend, as they dropped to 5.29 percent with an average .5 point, down from last week’s 5.33 percent. “Long- and short-term mortgage rates fell for the third consecutive week amid continuing signs of a slowing economy,” said Frank Nothaft, Freddie Mac vice president and chief economist.  “Retail sales fell for the fourth straight month in October and consumer sentiment remained near a 28-year low in November. In fact, the Federal Reserve during its October 28-29 committee meeting lowered its economic growth forecasts for 2008 and 2009, according to its minutes released this week.” Bankrate.com’s weekly survey also revealed modestly falling mortgage rates. The benchmark 30-year fixed-rate mortgage, according to Bankrate, fell 5 basis points from last week, to 6.39 percent, as the average 15-year fixed-rate mortgage slid 13 basis points, to 6.08 percent. “Historically speaking, mortgage rates will do the opposite of the economy,” said Barry Habib, CEO at Mortgage Market Guide, as reported by Bankrate. “In other words, they’ll improve as the economy weakens because a stronger economy means inflation.” This generally accepted rule of thumb doesn’t exactly forecast positive movement within the economy, at least in the near future. That forecast, however, assumes that agency MBS continue to tighten against Treasuries and move in more historically-consistent patterns; as we’ve seen in recent weeks, that’s anything but predictable. Write to Kelly Curran at [email protected] Disclosure: The author held no relevant investment positions when this story was published. Indirect holdings may exist via mutual fund investments. HW reporters and writers follow a strict disclosure policy, the first in the mortgage trade.