couple of options I can think of write a unlisted private option...

couple of options I can think of

write a unlisted private option from a "unrelated entity" and thus not have control and not have to report 5% holding?

One of the major holders having written a unlisted private option?

I think regardless having rights to %5 of a stock may trigger reporting anyway?

Option could be a unlisted swap. Maybe a swap, ratio swap for other shares in a different company with similar valuation

Can be a way to move profitability and defer tax ?

Get the register and resolve who the other party was for a start
There is rules regarding directors and management not showing if they have lessened or increased their interest via options or financing arrangements.

Interesting to see if any 3b announced or other movements on interests.

From market has there been enough volume traded to have had these trade on market since may?

Something unusual going on