Could this be at least part of it?
How many of you have ever heard of 'POMO' (the Federal Reserves 'Permanent Open Market Operations'), which is an ongoing program where the Federal Reserve periodically (this being almost weekly) infuses currency directly into the US stock markets. The markets go up with the infusions, and they fall if there is no infusion.
http://www.zerohedge.com/news/2013-08-1 ... -fight-fed
So, thanks to the US Treasury, we know that between January 2009 and April 2013, on days in which the Fed POMO was more than $5 billion, the stock market rose a total of 570 points, on days in which the POMO was less than $5 billion, the cumulative stock market gain was "only" 141 points, and when there was no POMO, the S&P gained... -51 points.
With the Fed openly and admittedly infusing capital directly into the stock markets on a very routine basis, and thereby driving them up, how can they still be called places for "honest price discovery" (the purported primary reason for why the stock markets exist)? This manipulation can account for essentially all of the gains seen for the S&P 500 Index.