How to Notify a Substantial Holding in Australia (2026): Step‑by‑step for Investors, Funds & Listed Companies

If you hold, or are about to hold, 5 per cent or more of the voting shares in an Australian listed company, you are legally required to lodge a substantial holding notice with both the company and the relevant market operator. Understanding how to notify a substantial holding in Australia in 2026 is especially urgent because ASIC’s draft Regulatory Guide RG222, released as an attachment to Consultation Paper CP387 in March 2026, expands disclosure obligations to capture equity derivatives and introduces the concept of a “deemed economic interest. ” Key obligations under the reformed regime commence on 4 December 2026, giving investors, fund managers and listed‑company compliance teams a narrow window to re‑engineer monitoring, calculation and filing processes.

This guide walks through every procedural step, from detecting a trigger event to lodging the notice within the statutory two‑business‑day deadline, and flags the common pitfalls that lead to regulatory action.

Overview of the Substantial Holding Disclosure Process

A substantial holding notice is the formal disclosure document that a person or entity must lodge when they acquire, change or cease to hold a substantial holding in a listed company or listed managed investment scheme. The obligation sits in Part 6C.1 of the Corporations Act 2001 (Cth) and is administered by the Australian Securities and Investments Commission (ASIC). ASIC’s existing guidance on what constitutes a “relevant interest” and how notices should be prepared is set out in Regulatory Guide RG5.

The disclosure regime serves a transparency purpose: it ensures the market, the issuer’s board and other investors can see who controls significant voting power. The foundational threshold is 5 per cent of total voting shares. Once a person’s relevant interest reaches or crosses that threshold, in either direction, a notice must be lodged. Subsequent movements of 1 per cent or more above or below the last‑disclosed position also trigger a fresh notice.

The 2026 reforms, as outlined in ASIC’s draft RG222 (Attachment 5 to CP387, published 10 March 2026), extend the reach of the regime. Under the current rules, only interests that confer voting power or the power to control the disposal of shares are captured. Under the draft regime, equity derivatives that convey economic exposure, even without voting rights, will also be caught through the new deemed economic interest concept. Industry observers expect this to significantly increase the number of disclosure events for hedge funds, total‑return‑swap counterparties and structured‑product issuers.

Notices must be given to both the listed entity (the company or scheme) and the market operator (typically ASX). The company is then required to release the notice to the market immediately upon receipt.

Eligibility and Prerequisites: Who Must Lodge a Substantial Holding Notice

The substantial holding disclosure requirements apply to any person, individual, corporation, fund, trust or partnership, who has a relevant interest in voting shares representing 5 per cent or more of total votes in a listed entity. The concept of “relevant interest” is broad and is defined in the Corporations Act. It captures not only registered ownership but also any power or control over shares, whether exercised through a trust, agreement, option or other arrangement.

What counts as a relevant interest

Under the Corporations Act, a person has a relevant interest in securities if they hold the securities, have the power to exercise or control the exercise of voting rights attached to the securities, or have the power to dispose of or control the disposal of the securities. This extends to interests held through nominees, custodians and sub‑custodians. If a fund manager has discretion over the voting or disposal of shares held in client portfolios, that manager holds a relevant interest in those shares, even though beneficial ownership resides with the client.

Associates and tracing

The regime aggregates the holdings of associates. A person’s associates include entities they control, entities that control them, and entities with whom they have entered into relevant agreements regarding the acquisition or disposal of shares or the exercise of voting rights. When determining whether the 5 per cent threshold has been crossed, the substantial holder must add together its own relevant interests and those of all associates. Tracing through nominee and custody chains is often the most complex element of the analysis, particularly for multi‑jurisdictional fund structures.

Deemed economic interest, the 2026 expansion

From 4 December 2026, holders must also include derivatives that deliver economic exposure to the underlying shares, even where no voting power or disposal control is conferred. The draft RG222 introduces the concept of deemed economic interest, which captures equity swaps, contracts for difference (CFDs), total‑return swaps, and physically settled options. The notional exposure under such instruments must be converted into a share‑equivalent figure and included in the holder’s aggregate disclosure. This significantly broadens the scope of what must be disclosed and will require investors to monitor derivative positions alongside physical holdings.

Quick eligibility decision tree

• Do you hold, or have power over, voting shares in an ASX‑listed entity? If yes, continue.
• Do your relevant interests (plus those of your associates) reach 5% of total votes? If yes, you must lodge an initial substantial holding notice.
• Do you hold equity derivatives that deliver economic exposure to the entity’s shares (from 4 December 2026)? If yes, include those positions when calculating your aggregate deemed economic interest.
• Has your previously disclosed position changed by 1% or more? If yes, lodge an updated notice.
• Have you ceased to hold a substantial holding? If yes, lodge a ceasing notice.

Step‑by‑Step Procedure: How to Notify a Substantial Holding in Australia 2026

The following numbered steps set out the end‑to‑end procedure for detecting, calculating, approving and lodging a substantial holding notice. Each step identifies the responsible function and the typical time it should take. The mandatory timeline table below provides a consolidated view.

Step 1, Monitor triggers and identify relevant interest

The disclosure obligation is triggered at the moment the holder becomes aware that it has acquired, changed or ceased to hold a substantial holding. “Becoming aware” includes the point at which the holder ought reasonably to have become aware, so relying on delayed trade confirmations is not a defence. Operations teams should configure real‑time alerts in portfolio management and order‑management systems that flag when a position in any ASX‑listed entity approaches 4.5 per cent of total votes, providing a buffer before the 5 per cent threshold is reached.

Data sources to monitor include executed trade confirmations, custody statements, prime‑broker reports, and, from 4 December 2026, derivative booking systems that record equity‑swap and CFD notional values. Where the holder uses multiple brokers or custodians, a consolidated position view must be maintained. The trigger date recorded at this step is the date from which the two‑business‑day disclosure timeline begins to run.

Step 2, Calculate relevant interest and deemed economic interest

Once a trigger is detected, the legal and operations teams must calculate the holder’s aggregate position. This involves two components: the relevant interest (shares over which the holder has voting or disposal power) and, under the 2026 reforms, the deemed economic interest (derivative exposure converted to a share equivalent).

Worked example 1, Fund with physical shares and options:

In this example, the fund’s physical shares alone sit below 5 per cent. However, when the call options (which confer a relevant interest because they are physically settled and grant disposal power on exercise) and the equity swap (which creates a deemed economic interest under draft RG222, despite being cash‑settled with no voting rights) are added, the aggregate position crosses the 5 per cent threshold. An initial substantial holding notice is required.

Worked example 2, Broker with client facilitation position:

The total‑return swap hedge, entered into to facilitate a client transaction, is now captured as a deemed economic interest. The broker must lodge a notice even though it does not intend to exercise voting influence. Operations teams should retain the calculation workbook, including ISIN, counterparty reference, and notional conversion methodology, as evidence of the calculation for ASIC inquiries.

Step 3, Prepare filing and obtain internal approvals

With the calculation confirmed, the responsible legal or compliance officer should draft the notice using the applicable form. Until ASIC confirms the final form of the proposed consolidated notice under draft RG222, the transitional approach is to use ASIC Form 603 (becoming a substantial holder), Form 604 (change in substantial holding), or Form 605 (ceasing to be a substantial holder), as appropriate.

The notice must include the holder’s name and address, the date the person became aware of the relevant event, details of the relevant interest (number of securities, nature of the interest, and any associates whose interests are included), and, from 4 December 2026, details of any deemed economic interest. Internal approval should follow a documented escalation ladder: the portfolio manager or desk head confirms the position data, the compliance officer verifies the threshold calculation, and an authorised signatory approves lodgement. Where time is tight, pre‑delegated signing authority can prevent delays.

Step 4, Lodge notice with the issuer and market operator

The completed notice must be given to both the listed entity (sent to the company secretary at the registered office or via the entity’s nominated electronic address) and the market operator (ASX, via the ASX Online platform or other approved channel). The statutory deadline is within 2 business days of becoming aware of the relevant event. Business days exclude Saturdays, Sundays and public holidays in the jurisdiction of the market operator.

The holder should retain a dated record of transmission, a read receipt, ASX lodgement confirmation or email timestamp, as proof of compliance. If the notice is lodged by an agent, the agent must be expressly authorised to act on the holder’s behalf. Upon receipt, the listed entity must immediately release the notice to the market via the ASX Market Announcements Platform and update its register of substantial holders.

Required Documents and Information

The following table summarises the documents and supporting information needed to complete and evidence a substantial holding notice lodgement. Ensuring these materials are assembled before the disclosure timeline begins to run is critical to meeting the two‑business‑day deadline.

All documents should be retained for a minimum of seven years, consistent with ASIC’s general record‑keeping expectations. Where the holder operates across multiple jurisdictions, ensure that each custodian’s records reconcile to the aggregate position reflected in the notice.

Timeline and Key Deadlines for Substantial Holding Disclosure

The disclosure timeline is measured in business days, not calendar days. Under the Corporations Act, a “business day” is a day that is not a Saturday, Sunday or public holiday in the place where the relevant market operator is located. For ASX‑listed entities, this means business days observed in Sydney.

The two‑business‑day rule in practice

Suppose a fund’s operations team detects on Monday afternoon (a business day) that its aggregate relevant interest in Company X has crossed 5 per cent. Monday is Day 0, the day of becoming aware. The fund must lodge the notice by close of business on Wednesday (Day 2). If Tuesday were a public holiday, the deadline would shift to Thursday.

Key 2026 transitional dates

The primary obligations under draft RG222, including the capture of equity derivatives as deemed economic interests and expanded tracing requirements, commence on 4 December 2026, as set out in ASIC’s Attachment 5 to CP387 published on 10 March 2026. Holders should treat the period between now and that date as a transitional window to reconfigure monitoring systems, update internal policies and train operations staff. ASIC’s Corporate Finance Update (Issue 28, 28 April 2026) provides further regulator commentary on the consultation timeline.

Ongoing update obligations

After the initial notice, any movement of 1 per cent or more in the holder’s relevant interest (or deemed economic interest, from 4 December 2026) requires a fresh notice (Form 604 or the consolidated notice equivalent). A ceasing notice (Form 605) is required when the holder’s aggregate position falls below 5 per cent. These update obligations also carry the same two‑business‑day disclosure timeline.

Costs, Fees and Tax Considerations

There is no ASIC filing fee for lodging a substantial holding notice electronically. The costs associated with the process are primarily operational and advisory. The table below provides indicative estimates; actual costs will vary depending on the complexity of the holder’s structure and the number of associate and derivative positions to be traced.

Lodging a substantial holding notice does not, in itself, trigger a capital gains tax event. However, the underlying transactions that give rise to the disclosure (purchases, disposals, derivative settlements) may have tax consequences. Holders should consult tax counsel separately on the tax treatment of the relevant transactions.

What Changes in 2026: ASIC CP387 and Draft RG222

ASIC’s draft Regulatory Guide RG222, published as Attachment 5 to CP387 on 10 March 2026, introduces several material changes to the substantial holding disclosure requirements. These changes are designed to close gaps in the existing regime where economic exposure to a company’s shares could be built up through derivatives without triggering any disclosure obligation.

Deemed economic interest

The centrepiece of the reform is the introduction of the deemed economic interest. Under the current rules, only interests that confer voting power or disposal control are captured. Under draft RG222, instruments that deliver economic exposure, including cash‑settled equity swaps, total‑return swaps, contracts for difference and options that do not include physical settlement, must be converted into a share‑equivalent figure and included in the holder’s aggregate position. The conversion methodology requires the holder to calculate the number of shares to which the instrument’s notional value corresponds, based on the current share price at the time of the relevant event.

Consolidated notice proposal

Draft RG222 proposes replacing the separate ASIC Form 603 (initial notice), Form 604 (change notice) and Form 605 (ceasing notice) with a single consolidated notice form. Until ASIC finalises the new form, the existing forms remain in transitional use. Early indications suggest the consolidated form will require additional fields for derivative exposures, including instrument type, counterparty, notional amount and settlement method.

Expanded tracing obligations

The draft guidance also strengthens tracing requirements for custodian and nominee chains. Holders must trace through to the ultimate controller of voting power, and the reforms clarify that a custodian which has discretion over voting, even if that discretion is rarely exercised, holds a relevant interest that must be aggregated with other positions held by the same entity or its associates.

Commencement date

The primary obligations under draft RG222 commence on 4 December 2026. ASIC has indicated in its Corporate Finance Update (Issue 28, 28 April 2026) that it expects market participants to use the intervening period to update systems and processes. The likely practical effect will be that compliance teams need to implement derivative‑monitoring feeds and revised calculation templates well before the commencement date.

Common Pitfalls and How to Avoid Them

• Omitting derivative exposure from the calculation. From 4 December 2026, cash‑settled equity swaps and CFDs must be included as deemed economic interests. Holders accustomed to the current regime may undercount their aggregate position. Mitigation: integrate derivative booking systems into the position‑monitoring workflow before commencement.
• Miscounting associates. Failing to aggregate holdings of controlled entities, co‑investors subject to relevant agreements, or entities sharing common directors can result in an undisclosed breach of the 5 per cent threshold. Mitigation: maintain a current associate register and review it whenever the group structure changes.
• Delayed internal escalation. The two‑business‑day window is tight. If the operations team detects a trigger but delays notifying legal or compliance, the deadline may be missed before the notice is even drafted. Mitigation: establish standing escalation protocols with pre‑delegated signing authority.
• Incorrect business‑day counting. Counting calendar days instead of business days, or using the wrong jurisdiction’s public holiday calendar, can lead to a notice being filed one day late. Mitigation: use the public holiday calendar for the jurisdiction of the market operator (Sydney for ASX‑listed entities).
• Using the wrong form. Filing a Form 604 (change notice) when a Form 603 (initial notice) is required, or vice versa, may result in ASIC querying the lodgement. Mitigation: confirm the correct form based on whether this is an initial acquisition, a change or a cessation of a substantial holding.
• Failing to notify both the company and the market operator. The statutory obligation requires notice to both the listed entity and the market operator. Lodging with only one is not compliant. Mitigation: build dual‑lodgement into the filing workflow as a mandatory checklist item.

Sources

1. ASIC, Attachment 5 to CP387 (Draft RG222) (10 March 2026)
2. ASIC, Regulatory Guide RG5: Relevant Interests and Substantial Holding Notices (27 March 2024)
3. Corporations Act 2001 (Cth), Federal Register of Legislation
4. ASIC, Corporate Finance Update Issue 28 (28 April 2026)
5. ASX, Regulation and Compliance
6. Australian Institute of Company Directors (AICD), Proposed Changes to the Listed Entity Disclosure Regime