I think we would all love to know the answer to that question. It's really quite interesting. If it is a big seller out there, at least the are somewhat doing it cautiously, and not just slamming the bid to drop the pps.
On the other hand, someone else is picking up those shares, even if there is someone unloading big time. It could be covering by the MM's, but I think it's fair game to say that everyone is guessing. If it's not Wessal, nor the MM's, who's next on the list. I doubt one buyer would be purchasing that many shares, and this has been going on now for awhile.
Just another of those "time will tell" what happens, when we quit seeing the big blocks played out as they've been.