I wrote this on my journal:
"Its similar to the Chuck Prince chair dance situation. Most of the big players understand that this market is overvalued and its only being held up by central bank policy. Yet they were all invested (sometimes with leverage) because if they didn't it would be fired by lagging the benchmark, thats why even guys like Hugh Hendry decided to 'get up and dance'. They all thought they could get out before the other guy when things started to turn. It did turn and when the key levels were being taken, selling by these players would just keep pilling. You also had the dip buyers being cleaned out too. Of course, it didn't help that HFTs simply vanished. Everybody was trying to get to the few chairs that were available. As a result, you had a quick repricing of the market. Thats my theory anyway"