ARIAD will have to deal with a half billion dollar damage to shareholders.... Obviously the management can't be that stupid as most shorts are on the board... Therefore, there must be material events behind the recent run... imo.
If ARIA does not clear this confusion about the rumor... they will be facing serious lawsuits... The very fact that they are not denying anything (for the last 4 days) is very indicative of something material behind the current run.
I am sure they are in the process of preparing a PR otherwise they would have already released a statement saying they have no idea why stock is behaving this way.... :) Maybe the management is preparing a Christmas gift to us all... :) Stay tuned!