Minimum acquisition threshold: delisting offer succeeds only if promoter post offer shareholding plus accepted bids reaches required majority and public participation. Regulation 17 requires a delisting offer to achieve a specified post offer promoter shareholding combined with shares accepted through eligible bids at the final Schedule II price to meet the statutory threshold and mandates a required level of demat shareholder participation in Book Building, subject to an exemption where proof of delivery of the letter of offer to all public shareholders is demonstrated; special calculation rules apply where the offer arises from substantial acquisition obligations and a distinct rule governs success where a counter offer has been made.