Different people use different styles of trading. Many just play the run up towards an event and sell just before the event. They won't make as much as those holding through a positive announcement, but, they won't lose with less than stellar news. It's just varied trading style.
Then, there are those that may be shorting at these levels. I personally, don't short biotech since the trade can turn against you too quickly.
As far as what to expect tomorrow, I truly hope there is definitively good news. Our society needs help for Alzheimer patients. That's why I'm still watching here. I truly hope they have the answers.
In Reply to 'DOLPHY'
How this stock trades baffles me. Only a fool would sell at these prices with the type of news we all expect tomorrow afternoon.