For those of you in Panic mode, look at the Major Holders of ISIS.
Fidelity, BlackRock, Artisan... 80% of ISIS is owned by institutions. Think all those managers are fools?
Even with the sale May 14th ISIS is still out preforming the market, earning more money, creating a deeper pipeline, and working it's way to be a future leader in the pharmaceutical industry. Think LONG term.
ISIS is on sale, buy it if you can. If it drops some more it wasn't a bad purchase, it's an opportunity to cost average your self in with a better sales price. Think two years from now, not tomorrow.