There is clearly someone with either a bot or manual sell of...

There is clearly someone with either a bot or manual sell of 100-200k shares per open. Why they decided to do it this way is anyone's guess, but it's fairly easy to run two bots at the same time and get people to sell to you later in the day, so you can entice people to buy on open.

If seller is behind a custodian or nominee (in reference to @rabbitoh comment about putting their hand up) then the company can't see on the daily register who the sellers is - but from what I understand the murky hints and tips from an ex-broker for forcefully obtaining shareholder lists from custodians/nominees has been sent to NXM