I love to read all the "conspiracy" theories, they make for great entertainment! When you are long and the stock is going down - it's because someone is "manipulating" it. But when the stock goes up it's because you (I mean anyone - no one in particular) are a genious. That's just how the mindset of the average retail investor works.
Option premium has been wrung out of MNTA now - so options are relatively cheap if you need/want to hedge or speculate. But AMAG might be a similar example where it collapsed post approval from $75 area to $25. AMAG had a $1.5b++ market cap right after approval and slowly bled down to about $500m. Sometimes the hype/expectations are much greater then the "new" reality and the issues/problems having to market/sell a real product provide many more nuances then "approval vs non-approval"
I can't think of one company which has recently gotten approval that isn't dramitically lower then the announcement day and MANY are actually lower then their "pre approval" levels. It seems people have been buying the "dream" and selling the news - atleast for the first 6 - 12 months after approval.