It is impossible to definitively give a reason as to why something as uncontrollable as Bitcoin changes in price.
But yeah, probably.
But yeah, probably.
When you have, on the same day:
a) Greenspan's announcement saying bitcoin is a bubble, and using the "no intrinsic value" argument
b) China effectively banning bitcoin (not that we have the specifics to say that "ban" is the best term yet)
...it's not going to do wonders for the price.