I've been holding ACOR for quite some time now, shorting it of course. Yes, I've lost money. Here's the reason behind ACOR run up for the last 11 days.
Mr. Daniel Loebs of Third Point decide to purchase up to 2,2M share on the open market for the last 10 days or so. His starting price was around $16 - $17. Mr. Loebs is a big hedge fund guy with office in 399 Madison Ave. NY.
All those who hold short position was 'short squeeze' for the last 10 days. It's hurts!! However, it's was completed on Feb 13. Thus, ACOR is back to normal volume, roughly 50K share trading everyday.
For those who did not cover, like myself. Good job!! I've heard rumor that Mr. Loebs is a quick mover, meaning that he likely move out quickly gaining 7 - 8% on his purchase.