It was, as I understand it, a shareholders meeting. Many people buy 1 share of a stock to get closer to the CEO's/other management during those days (sometimes two days). My understanding is that the first day of this shareholder event (all held at the same hotel) was a run up to the second day, which was the fohttps://finance.yahoo.com/news/unitedhealth-group-insiders-sell-us-120027214.htmlrmal meet-the-shareholders day. Dissenting shareholders for this particular equity company might be fairly large.
Other stockholders were miffed/worried about the legal troubles and possible criminal fraud at UHC:
The reason for the sell off is a rabbit hole.
So all someone has to do to get access to such events is buy 1 share of stock. Further, the crowd gathers and it's not exactly orderly once it starts (this particular company has had its share of protesters).
If the perp came into town 10 or more days earlier, they had quite a bit of time to scope out the itinerary of the CEO of the company they hated (if that was the motivation).
BT's wife told NBC that he had received death threats. I can understand how he decided to simply defy those threats (he was, after all, paid to do exactly that and I am boggled by his actual paycheck). I am also boggled by this company's reported profits and returns to equity share holders. All of this was the subject matter of this "conference." Feelings were heated.
IMO.
This was not a shareholder's meeting.
It was a meeting for investors and had a closed attendance. It was not open to general shareholders.