RE:Major shareholders If they are considered " insiders" they have to report trades...as far as I know only 1 of the brothers from MEDI is an insider and hasn't dumped any and nobody from EV is an insider.
All other holders of these shares both MEDI and EV can sell or buy at will and nobody would know...this is how I see it.
What we do know is tens of millions of shares were sold from 17 down ( from anonymous) but most of that heavy selling stopped 6 months ago or so
I believe lots of these shares came from the non insider medi guy but have no proof, just a belief.