According to Javier Silva, a senior research and policy associate with Demos, a New York think tank and public policy organization, homeowners' equity fell from an average of 68.3 percent to 55 percent between 1973 and 2004. Americans now own a smaller stake in their homes than they used to. In the 1950s, they owned nearly 80 percent.
If real estate appreciation slows or declines, homeowners without equity that is firmly established may find themselves owing more than their houses are worth. And if interest rates rise significantly, homeowners with adjustable-rate mortgages may not be able to meet the higher payments or, worse, to refinance their homes at a fixed rate.