“Hmm, what would have happened if the Federal Reserve hadn’t dumped trillions of dollars into the mortgage market, and the Federal housing agencies hadn’t subsidized mortgages and housing with 3% down payments and tax credits? Perhaps all the trillions of dollars of intervention has accomplished is extend Phase 2. Central bank and state manipulation distorted the symmetry of housing’s decline, but did they stave off Phase 3 permanently? If bubbles eventually revert to their starting level, Phase 3–capitulation and a return to pre-bubble prices–still lies ahead.”
http://charleshughsmith.blogspot.com/2013/04/bubble-symmetry-and-housing.html