Just as all bubbles have broken, these bubbles did. Far from being a surprise, the bubbles breaking were absolutely not outlier events, contrary to protestations. The bubbles forming in 1998 and 1999 and in 2003 through 2007 were the outlier events. The U.S. housing market, which was a clear bubble with prices at least 30% above a previous very stable trend, is well on its way back to normal, and equities and risktaking may well have made it all the way back.
~ Jeremy Grantham, "Reaping the Whirlwind," GMO Quarterly Letter, October, 2008