It appears that it was a coordinated action planned many days in advance. Without doubt also related to coronovirus.

We looked at the crypto index CMC200 and CMC200 without bitcoin which are volume weighted average price synthetic indices, now present in the mainstream with Nasdaq, Bloomberg, Reuters, Yahoo etc. Both indices culminated on 14 February 2020. In comparison, Nasdaq and S+P 500 CAC 40 DAX etc have all peaked on 19 Feb 2020.