That’s what a majority of mortgage bankers are worried about, according to a survey of North American bank risk managers conducted by analytical software company FICO. The report, released Tuesday, shows that more than 56% of mortgage bankers surveyed by FICO are concerned that “an unsustainable real estate bubble is inflating.”

Andrew Jennings, FICO’s chief analytics officer, is not surprised that a “bifurcated” home loan market has inspired fear among lenders in the U.S. and Canada over the risk present in residential mortgages. “Six million homeowners in the U.S. are still underwater on their mortgages, with the average negative equity a whopping 33 percent. Yet with home prices soaring in many cities, total homeowner equity in the U.S. is at its highest level since late 2007. That doesn’t feel like a healthy, sustainable growth situation,” Jennings said in a statement.