I am in from the 2's as well. To what do you attribute the almost frenzied (but orderly) buying? Since investor day the volume has been very heavy. It is far and away my biggest holding, and I too am tempted at times to sell some.
Problem I have is that I can't find another bio that I believe has as much potential, say 1-2 years out. From a short term trading perspective, a pullback is in order and would be healthy, IMO.
I guess this is the kind of problem investors dream of, so we should be grateful.