I don’t follow VNDA closely; however, if the 25% pop yesterday was due solely to the increased stake by Baker Bros., it’s likely an overreaction.
Still, it’s dangerous to short a company with an enterprise value of only $200M unless you know it’s a certain loser—e.g. FCSC in Jun 2011 following FDA approval of laViv. VNDA isn’t in that category, IMO, so I wouldn’t short it.