During the lat 15 minutes, there were four quite red spikes of for a total of 115k shares. So, yes, somebody dumped some shares (which some else bought), but I wouldn't exactly call it a sell off (it comes to about a tenth of one percent of total shares outstanding...)
That said, it was about 16% of the total day's trading that happened in those four red minutes - which does have a dramatic effect on pps when concentrated like that. Looks kinda intentional to me, someone wanting to drive down the pps....but then I've always been a conspiracy theorist.