They have a lot of reason why crypto's market downturn today, the first one is the increasing regulatory of cryptocurrency exchanges because many attempted hacking of traders to be more secured. Read more about this.

What Caused The Recent Cryptocurrency Downturn
https://www.forbes.com/sites/outofasia/2018/03/05/explaining-the-dip-what-caused-the-recent-cryptocurrency-downturn/#4c9c39b45ccd