Substantial holding notices: the rules now, and from 4 December 2026

Section 9 of the Act says “a person has a substantial holding in a body corporate, listed registered scheme or listed notified foreign passport fund, if” the total votes attached to voting shares or interests in which they or their associates have relevant interests is “5% or more of the total number of votes”. The count includes some interests the Act would otherwise exclude, such as market traded options and conditional agreements. A person who has made a takeover bid for voting shares also has a substantial holding while the bid period runs.

The information to be given is the person’s name and address, details of their relevant interest and of any relevant agreement, the name of each associate with a relevant interest, and, for a movement, its size and date. A movement of at least 1% means the person’s percentage of the total votes has gone up or down by 1 or more percentage points from the percentage they last disclosed.

ASIC’s page for Form 603 says to lodge it with the relevant listed entity and securities exchange, and not to send it to ASIC; the legislative reference it gives is section 671B. Contravening section 671B(1) is an offence, and also an offence of strict liability.

The Treasury Laws Amendment (Strengthening Financial Systems and Other Measures) Act 2025 received the Royal Assent on 4 December 2025. Its commencement table starts Schedule 1 on 4 December 2026, and item 21 of that Schedule reads “Repeal the Part, substitute:” before setting out the new Part 6C.1.

The new section 671A sorts entities into “Chapter 6C bodies”: a listed company, a listed registered scheme, a listed notified foreign passport fund, and other listed bodies whether or not incorporated or formed in Australia. Each has a key person: the company, the responsible entity, the operator, or the body itself.

Section 671B(3) then says the person “must, in accordance with this section and sections 671BA, 671BE and 671BF, give the information referred to in section 671BB” to the key person and each relevant market operator, and a note adds that it must be given even if the situation changes in the meantime. Contravening that subsection is an offence, and an offence of strict liability.

Holdings built from derivatives

Section 671BB widens what the notice must show. Beside the person’s holding percentage, it asks for their “derivative-based holding percentage”, and, where that is above nil, its parts and any offsetting short positions. New section 671D applies the Part to a person without a substantial holding as if they had one, where a deemed economic interest held by them or an associate would give them a substantial holding if it were a relevant interest. A disclosable movement is, in the first case section 671BK gives, a rise or fall of 1 or more percentage points from the holding percentage or derivative-based holding percentage the person last disclosed.

ASIC’s RG 5, issued 30 July 2026, discusses the deemed economic interest and notes that the requirements in Schedule 1 commence on 4 December 2026.

Under both versions, information a person becomes aware of during a bid period is due “by 9.30 am on the next trading day of the relevant financial market”. A bidder has a notice of its own to give as well: under the current section when it makes the bid, and from 4 December 2026 when the bid period starts. The bid’s own steps are in takeover bids, step by step, and the 20% line in the 20 per cent rule.