Yes - BoA is the beneficial owner, but they very likely have a...

Yes - BoA is the beneficial owner, but they very likely have a swap agreement with one or numerous different investors who are taking all the risk and are the actual underlying investor. This is very common.

BoA does not even need to have executed the trade. Basically the investors are likely instos who PB will BoA and have give up agreements with whoever actually executed the trade. Then when the stock is cleared or given up to BoA it can be done on swap or cash. If swap then BoA appears as the beneficial holder, if cash the actual buyer remains the beneficial owner.

With Comsec etc they are just acting as the broker to facilitate the buy and sells in the market. But the actual buyer remains the beneficial holder.

In any event, BoA does not have a prop desk in Australia (and I don't think they manage any funds in Oz) so if BoA did buy it, which part of the bank is actually holding it?

I would say it is 99.99% likely a swap trade.