GMC - FA, TA, page-89

Furthermore, for each 1% (or more) change in holding a Form 604 “Notice of Change of Interests of Substantial Shareholder” must be lodged. And, if the holding falls below 5% a Form 605 “Notice of Ceasing to be a Substantial Shareholder” must be lodged. These Forms must be lodged within 2 business days after they become aware of the transaction or change in % holding and by 9:30am next stock exchange trading day in a takeover situation.