Play this downwards for now.....invest in Put Options!!!!
LOL I read your 'advice' and had to chuckle.
First your claim years of experience trading stocks and yet recommend 'options' why is that?
If you had vast experience why did you not short earlier?
I have a vastly different experience in trading BIO's then you. I have also seen the initial 'pop' then a 2 to 3days of pounding down then when the bottom is exhausted the stock moves up and through the previous high .
I would never pretend to offer direct advice with out disclaimer of do your own DD. As for the stock price on a specific day anything can happen as we saw on Tuesday and Wednesday.
As for DNDN, i am to the long side on it.
As your comment 'its' only 4 months' obviously you don't deal with medical research and statistics much to understand what the relevance/importance of the study was.