People are cashing out is my best guess. You knew the bull run on BTC had to end in the coming days and it stopped short right up to the CME and CBOE opening for futures any coincidence there? I think not it seems like it was a buy the rumor sell the news kinda gig. I personally think BTC will end up going down even further than where it is now and dragging altcoins with it. I am hoping however the BTC money flows into alts because I am more alt based than btc based atm.