Ann: St George Commences Drilling at Paterson, page-151

OK. Here is an education for you.
I managed an institutional fund for 30 years (for context).
In my fund I might have 5 wholesale accounts or clients.
I buy 100m SGQ and allocate to each account according to size of FUM.
Those 5 wholesale accounts have their own custody arrangements. I have no control over this. In fact the wholesale client may have 3 different investment managers, all operating with the same custodian.
This is not some cunning plan by the insto fund manager, we never had any control over custody arrangements. In fact got very annoyed with clients who also often loaned out their securities...how weird is that? I buy the stock for say AusSuper then they lodge it with UBS (for example) who lend it to Regal who shorts it!
As for brokers knowing your plans and front running...seriously? That's a death wish for a broker hoping to maintain a relationship with a major insto client.
And as an insto fund manager, running the same trading strategy thru different brokers is a recipe for disaster, not to mention Mr ASIC knocking on the door. Pump and dump? Insto fund manager risks far too much for that. Next level down trading funds, hedge funds, high net worths? Not sure.

Those substantial shareholder notices only really tell you who is holding the stock as custodian and who the fund manager is.
There's no cunning plan. Different underlying clients have different custodians.