Market manipulation is the focus in a number of comments so I'll create a post to hang comments onto.
The conspiracy theory du jour is that treasuries are purchased and the banks receiving the funds leverage them to pop the stock market, ostensibly through either HFT or futures trades or both. The funds appear in the marketplace at 2:00. The large banks, in my mind, now are reducing their proprietary trading operations due to new regulations. Investment banks (those that are not chartered as commercial banks) don't have this restriction. I believe Goldman Sachs is wildly unethical and would manipulate if they did not fear any repercussions. The government has no such fears and has the motive to make buy-side manipulation. The only reason short squeezes exist is fear of getting taken out by forced delivery by the loaning broker and the smaller size of the short population. This makes the short side easier to pop out of position. I would not put this past Goldman Sachs, but how would they 100% cover their tracks? If they are found out they would lose their franchise to steal in less egregious ways. The Fed and Treasury have no such fear. So, GS is a possible for me.
Seeing the market pop up from 2:00 on so consistently has shaken my belief that the market is too big to manipulate.