Quote from Specterx:
It has nothing to do with fundamental challenges to our society, but everything to do with the outlook for business earnings growth.
The facts are that businesses have cut to the bone, growth in earnings must now come from higher sales. What will be the engine for higher sales? In the past, the engine was debt accumulation - but that era has ended (despite the frantic attempts to restart the party 2007-style). At the very least we need a period of rebalancing, and at the worst we're headed for some kind of systemic implosion. In either case I expect we'll see much lower valuations sometime in the next few years, and that will be the time to buy (note that a number of stocks were quite attractively valued back in early 09).
There's not a shot I'm going to buy stocks at PEs of 15+ given the current fundamental backdrop.