"Without calling the overall national issue a bubble, it's pretty clear that it's an unsustainable underlying pattern. What we see are a number of forces, which are, as far as I can judge, not infinitely projectable," he said.
But when home prices slow, only those who purchased homes just as the prices begin to drop will be impacted by the decline, Greenspan said.
"The number of occasions in which an average level of prices in the United States have actually gone down are very rare," he said.
"Even if there are declines in prices, the significant run-up to date has so increased equity in homes that only those who have purchased very recently, purchased just before prices actually literally go down, are going to have problems," he said.
But when home prices slow, only those who purchased homes just as the prices begin to drop will be impacted by the decline, Greenspan said.
"The number of occasions in which an average level of prices in the United States have actually gone down are very rare," he said.
"Even if there are declines in prices, the significant run-up to date has so increased equity in homes that only those who have purchased very recently, purchased just before prices actually literally go down, are going to have problems," he said.