The Chinese government banned ICOs. Naturally as a result, alt coins started dropping. People are fearful they won't be able to get their money out with the government cracking down.
For the next couple of days I think it will blow over and go back up, but only time will tell.
this may be the beginning of the end of cryptocurrency? because i think that other governments can take this as an example with all this repercussions...and let's be honest ... wich powerful government does not want to have full control over money?