Mortgage bankers in Canada and the United States are concerned that another real estate bubble may be building, according to a new survey.

A survey of risk managers at North American banks that was conducted for analytics software firm, FICO, by the Professional Risk Managers’ International Association (PRMIA), found that 56% of respondents directly involved in mortgage lending expressed concern that “an unsustainable real estate bubble is inflating.”

“Six million homeowners in the U.S. are still underwater on their mortgages, with the average negative equity a whopping 33%. 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,” said Dr. Andrew Jennings, chief analytics officer at FICO and head of FICO Labs. “No wonder many lenders in both Canada and the U.S. are concerned about the risk in residential mortgages.”

The firm also reports that 59% of respondents cited “high debt-to-income ratio” as their top concern when approving loans. This far outpaces the next most common concern, “multiple recent applications for credit”, at just 13%.

“As consumer confidence picks up and people increase their borrowing, lenders are understandably concerned about growing indebtedness,” said Mike Gordon, executive vice president of sales, services and marketing at FICO. “For the last two quarters, around 65% of our respondents said they think credit card balances are headed higher. Those are the two highest figures we’ve ever seen in this survey. When I talk with bankers, they tell me they’re happy to see growing consumer optimism, but they’re wary of a return to reckless borrowing.”

The firm also reports that survey respondents throughout the U.S. and Canada are more optimistic about small business lending. In the latest survey, 26% said they expected delinquencies to increase on small business loans in the next six months, down from 34% last quarter.

“94% of our survey’s Canadian respondents believe lending among small business owners is expected to rise or remain the same over the next six months,” said Kevin Deveau, managing director, FICO Canada. “This is a positive sign, which points to improved optimism across sectors and also indicates continued growth in the Canadian economy. Coupled with a low interest rate environment, Canadian small businesses are well positioned to flourish in the remainder of 2014.”

Additionally, it reports that only 28% of respondents are concerned that the supply of credit for small businesses would fail to meet demand over the next six months, down from 40% last quarter.

The results are based on a survey of 203 risk managers at banks throughout the U.S. and Canada that was carried out in May.