Henry Blodget speculates on Huffington that the S&P 500 could go as low as 300 (it’s at 700 now). Theory based on bottom-out PE ratios after bubbles; these can go to 5x, and we’re at 12x.  

Henry suspects that as the bubble we had was the biggest ever 40xPE, the correction will end up being the lowest.  A little bit of voodoo economics, yes, maybe.  One has to ask, still, if interest rates went negative in Japan 10 years ago, why not stock prices in the US?  People might have to be paid to hold on to paper that has a high likelihood of being worth less in the future.