One upside to the downturn in the U.S. stock market is a sharp drop in mortgage rates. Those rates follow the yield on the 10-year Treasury bond and on pricing in agency mortgage-backed securities; as investors rush to the comparative safety of the bond market, yields fall and so do rates.
It's not a perfect correlation, however, since there are other factors weighing on today's lenders, such as new regulations.
The average rate on the 30-year fixed conforming mortgage hit 4.34 percent Friday, down from 4.50 percent just a week earlier, according to Mortgage News Daily. Lenders haven't offered rates that low since November.
(Read more: Cold weather puts chill on home sales)
"This correction is bigger than I would have expected," said Matthew Graham, COO of Mortgage News Daily, who points out that this week's jobs report could send rates right back in the other direction.
A weak report out Monday morning on U.S. manufacturing in January was well below expectations and the weakest since May. That is only adding to the flight from stocks and the boon to bonds. Demand for mortgage-backed securities spiked right at 10 a.m., when the report was released.
The report itself also builds a case for the potential that we could be seeing a slowdown in the broader economy, which may show up in the jobs report Friday.
"The pressure is now on for the economy to show a rebound in February," wrote analyst Peter Boockvar of The Lindsey Group.
The rate moves may seem small, and they are. In fact, for every quarter of a point drop, the average monthly mortgage payment on a $200,000 loan falls by just $30. The big impact is entirely psychological.
When rates suddenly drop, borrowers rush to refinance (if it's worth their while), and some buyers jump off the fence. The trouble right now is that the wider economic picture may be having a greater psychological impact on housing.
"I think it won't be a help to the housing recovery if the drop in rates is happening because the overall U.S. economy (and global one for that matter) is slowing down," said Boockvar.
(Read more: Buyers of new homes are seeing more barriers)
Rates for the very best borrowers at the most aggressive lenders could hit 4.25 percent Monday, which has some questioning how low they can go and for how long.
(Read more: Why mortgage rates aren't higher ... yet)
"This focus on 'emerging market' drama and the stock selloff is just helping set up for the next move higher in rates," argued Graham. "Turkish Lira?! Are you kidding me?! Something else would have to change in order for the longer-term trend to NOT remain higher in rates."
—By CNBC's Diana Olick. Follow her on Twitter @Diana_Olick.
Questions? Comments? facebook.com/DianaOlickCNBC