What happened? Just the same Asian stories that S Korea is considering stricter AML policy and even considering closure of Crypto Exchanges as well as China is planning to do the same... But is this something new to you? We are being bombarded with the same type of news since September 2017.
Plain and simple: one of cryptoplayers with above than averaged cryptoassets is selling own stack (yes, the market is very thin, even some of your orders can move it slightly), then the crowd sees the plunging prices and joins this race. That's it!