A recent report from Zillow suggests that in some areas, negative equity is actually deepening. According to the report, despite home values climbing 6 percent in 2014, negative equity deepened in 21 of the top 50 metropolitan areas during the last quarter of 2014. Homes that are built in areas that were hit hard by the crises: Las Vegas, Phoenix, and Tampa are especially vulnerable to stagnant and deepening negative-equity issues. So are homes that were built during the sprawl phase—when homebuilders headed to the fringes of metropolitan areas to build. Now, as my colleague Alana Semuels has reported, homes remain vacant, abandoned, or foreclosed, and some owners are so upside-down on their mortgages that selling isn’t a viable option.

Walker and his fellow owner moved out of the property around 2010 but they quickly realized that selling would only cement their losses. So for the past few years, they’ve rented it out, at a loss. They’re hoping a recent interest-rate reduction, will help them break even on outgoing mortgage payments and incoming rent. But even if he continues to rent the property for less than his monthly payments, Walker realizes he’s one of the fortunate ones. The poor performance of the property, while disheartening, isn’t financially devastating for him. He and his roommate are able to subsidize their mortgage with rental income, and still carry on their day-to-day lives elsewhere.

For many others, a home mired in debt is much more limiting. Those who can’t take a loss on selling or renting a property that is still deeply underwater are forced to sit tight, or use credit-damaging options like foreclosure or a short sale to get out from under the financial burden of a problematic property.

“These homeowners are stuck, and that will have a fairly big impact on the markets,” says Gudell.