"Now, suppose that a homeowner puts down only 3% of their own money or 3.5% for the FHA. That means if prices go down by only 3%, the house will be in negative equity and it would pay the homeowner just to walk away and say, "The house now is worth less than the mortgage I owe. I think I'm just going to move out and buy a cheaper house." So it's very risky when you have only a 3% or 3.5% equity for the loan. The bank really isn't left with much cushion as collateral."