US home equity fell below 50 percent for the first time since 1945. Home owner's equity dipped to 47.9 percent in the fourth quarter. Home equity is calculated as the fair market value of a home less the mortgage debt. According to Economy.com 8.8 million homeowners representing slightly over 10 percent of American homes will have zero or negative equity by the end of the month. American equity in homes as been declining gradually as homeowners refinance homes to take out equity, borrow up to 100% to purchase a home and take out lines of credit. As market values for homes decline the homeowners' equity falls. Standard & Poor's/Case-Shiller index showed home prices fell by 8.9 in the last quarter of 2007.