You'd almost need to monitor broker activity daily and keep...

You'd almost need to monitor broker activity daily and keep some kind of log to identify any trends of significance, but given lack of change in the top shareholders I'm not sure what you'd find. It's not impossible you could have multiple parties working together with a common goal of accumulating at lower prices whereby they systematically cross stock to one another at gradually lower prices. With both parties sharing the buying and selling they could potentially maintain small positions that don't trigger the 5% threshold and mandatory disclosure. The only flaw with that theory is that whilst they may achieve the goal of getting the price down, nobody would have acquired a material holding so what is the point? Hard to know. (This of course is theorising only)