Centurion is allowed to short the shares, but only to the extent that they know they will be receiving them. Don't know if that restriction is in place yet. But since Centurion has no control over how many shares they will get (depends on the amount of the LOC SFMI exercises), it would be dumb for them to short any more than a minimal amount, especially if SFMI has not told them the amount of any block to be exercised. Also, it would be dumb to short when the price is this low, anyway. All assuming Centurion's aim is to short. From what I've heard, they will be keeping any shares at least for a while.