"In Shiller's view, a real price decline of as much as 50% in U.S. home prices over the next decade isn't beyond the realm of possibility. Such a drop would be less catastrophic than it might seem at first blush. Like any economist, Shiller adjusts annual returns for inflation, which tends to amplify any downturn and mute upturns in nominal home prices. Thus he foresees only a 20% to 25% cumulative decline in nominal prices (which works out to about an average of 2% a year over the decade) with the loss of purchasing power from 3% annual inflation accounting for the remainder of the "real" decline. Still, that would be a crushing blow to anyone counting on rising home values to bail him out of any financial problems.
Such real declines aren't unprecedented. Los Angeles-area home prices fell over 40% in real terms between 1989 and 1997 before beginning a sharp ascent. That drop was largely attributed to job losses from the contraction of the aerospace and defense industries in Southern California in the late 'Eighties and the 'Nineties."