This is what is happening to many biotechs over the last few years its a common trap, and NWBO was not the only one. As a matter of fact, I wrote about this phenomenon 14 months ago and was of course shut down here.
Longs load up on anticipation of TLD, then an attack on the SP after positive TLD, Longs then panic and start selling to pocket their gains from the last weeks in anticipation of TLD. Short sellers who started the panic cover their short position. I read an extensive article about it in Yahoo Finance two years ago. It works really well because many longs think they can have a nice gain after TLD and there are no longs who want to buy after the fact of TLD.