Everyone talks about the shadow market, but no one seems to know how big it is. CoreLogic economist Sam Khater is taking steps to quantify that.

In a study, he says rental listings from single family homes are a growing part of MLS listings, accoring to UPI. Right now, they constitute 16.1 percent of all listings--double the number in 2008. Overall, he says the share of for-sale rentals rose 13.3 percent last year. Not surprisingly, Khater saw a strong correlation between distressed markets and areas with the most single family rentals.

The single market accounts for 21 million rental units or 52 percent of the entire residential rental market. Khater told UPI that single family rentals actually do better than apartments on a per foot basis--securing 1.5 to 1.6 times more.

Signs are that there’s already strong interest in the REO-to-rental program. Does Khater’s work make it look even more appealing to investors?