The stock dropped precipitously at exactly 8:40 - which is the time the presentation started.
Not the time the presentation disclosed any negative data... just the time the presentation started.
A post on twitter says it best... this thing was dropped 5 points to trigger all of the stop loss orders. All of those stocks were then taken and purchased - for the real gain which is right in front of us.
It's a rigged game. We're armed with peashooters and they've all got cruise missiles. I'm new to this, but I know with biotech, ultimately, you've got to do all the research you can, make your best educated guess, then rely on and stick with your judgement. SRPT dropped 10% the day before it skyrocketed. VRTX plunges and then bounces back within minutes. Hedge fund managers, MMs, and whoever else is in on "the game" work it so the little retail investor will bail and lose.
While you may be able to ascribe the early action as day/hf traders running stops or inciting panic, the current action is just typical of the weakness this stock always exhibits. Bid/ask is tight and you can buy or sell volume here. The data seems solid but it was obviously a horrible risk/reward trade to be long going into it. $1 upside versus who knows how huge the downside would have been if the data disappointed. Very discouraging.