Lagging inventories are contradicting reports of a "buyer's market" for housing.

Housing inventories, according to data from the National Association of Realtors’ Realtor.com, are down 20 percent from last year to 2.19 million.

That’s the lowest level since the site began tracking inventories in 2007, and it poses a unique challenge to the buyer’s market, which is seeking to capitalize on historically low interest rates and the most affordable home prices since the ’70s.

Two factors have primarily contributed to the shortage: homeowners are reluctant to sell their homes and take significant haircuts with the stressed prices, and banks are sluggishly re-introducing foreclosed properties to the marketplace after 2010’s infamous “robo signing” scandal. Some estimates put the “shadow” housing inventories – homes either in foreclosure or that are being withheld by stingy homeowners – at more than 1 million.

The result, said Ross Kutash, an attorney in Los Angeles, is a housing market of little precedent.

“On paper, all of the conditions are great for buying, but the reality doesn’t seem to match that,” Kutash said. “I wouldn’t describe it as a buyer’s market so much as no market at all.”

Also affected is the quality of the available homes. Buyers may be readily present, but the crop of homes on the market does not seem to match their interests, said Realtor Joan Downing.

“The inventory (of quality housing) is low, so it’s hard for buyers to find their dream home,” said Downing, who works in Bloomfield Hills, Mich., a suburb of Detroit. “That’s been our challenge more than anything: finding the inventory for the clients. Nobody’s complaining about the pricing or the interest rates.”

Detroit is among the harder hit cities in the country, in terms of inventory. Inventory is down in the Motor City by 28 percent, but that lags far behind the 49 percent decline in Miami, 48 percent in Phoenix and 46 percent in Orlando.

With such stark numbers, solutions would seem difficult to come by, but according to Redfin’s Glenn Kelman, the solution could be a complete crime against the laws of supply and demand.

“As weak as demand is, inventory has been weaker,” said Glenn Kelman, chief executive of Redfin Corp., a Seattle real-estate brokerage firm that does business in 13 states. “Right now, the absence of inventory is the limiting factor on sales volume.”