I've been long ISIS since the 60 level, but haven't been able to find any reason behind today's 7% move up - no news or chatter of any substance anywhere I could find that would support the move today. Anyone have anything that would support this kind of move.
If you review the Form 4s, believe you'll find that only a fraction were set aside for tax liabilities - looks like in the 25% +/- range, which is probably about right considering executives compensation.
Daffy, I don't believe it's a requirement, but rather just good financial sense. The granting of shares under a company incentive plan creates a tax liability - setting aside shares to satisfy the liability makes sense. I've seen this same thing happen often with officers in many companies. Seems to be a fairly standard practice.
Haven't had a chance to review every recent Form 4, but did check a dozen or so, and found all of them involved shares automatically withheld upon vesting of restricted stock to satisfy tax withholding obligations. No evidence they were sold to reduce a position.