It is no different than any other stock that trades on the big boards.
During Earnings season or FDA decisions no-one (besides insiders) know whether earnings or decisions will be positive. So you get a lot of people selling just prior to the dates who are not willing to take the risk of holding through.
Do you accept the risk and hold until news comes out or sell prior in order to limit the downside if something negative happens.
Flip a coin here and choose. In or out. I don't have a lot invested and I'm sticking around. If people are losing sleep over this they have too much invested.