ACCC releases eagerly anticipated merger guidelines for new merger regime

From 1 January 2026, merger parties that trigger specified thresholds will be required to notify the ACCC and obtain clearance before completing their transactions, or risk facing penalties. Parties to a proposed acquisition should now start to consider the impact of the regime change as deals not finalised before 31 December 2025 risk having to refile under the new regime.

Parties may seek to notify under the new regime from 1 July this year.

The ACCC has now released its draft merger assessment guidelines for public consultation between 20 March and 17 April 2025. The guidelines aim to provide assistance for merger parties looking to understand the ACCC's analytical approach to any notified acquisitions under the new regime. It is the first time that new merger guidelines have been issued since 2008. The ACCC's analytical approach has changed materially in that time, and this is the first time that the ACCC has set out guidance on its expected competition analysis of "killer" mergers, creeping acquisitions, mergers involving multisided platforms, mergers involving competing buyers, and acquisitions of a firm proposing to enter the acquirer's market.

The new Guidelines better align with the ACCC's current approach, compared to the previous guidelines.

Examples of possibly harmful mergers

The guidelines explain the analytical approach that will be adopted by the ACCC under the new regime, including some new examples such as:

• acquisitions of potential or nascent competitors that may prevent a competitor from entering or expanding in a way that may have increased competition
• mergers involving the linking or integration of goods or services, particularly in relation to platforms; and
• a firm serially acquiring smaller firms, allowing the firm to strengthen or entrench its market power.

In addition to the general analytical guidance, the ACCC has provided guidance on certain specific merger issues, including:

Creeping or serial acquisitions

The ACCC will assess a buyer’s acquisitions in the same or related markets over the past three years. It is particularly concerned where a firm acquires a series of smaller companies over time, consolidating them to obtain substantial market power, lessen competition, or entrench existing market dominance.

The ACCC will be on the lookout for serial acquisitions that result in:

• increased incremental market concentration
• difficulties for small or potential competitors reaching sufficient scale to compete
• the buyer maintaining a 'stable' of brands that creates the perception of alternative options when this is not the case, raising barriers to entry
• reduction in competition between competing chain stores
• reduced competition at multiple functional levels of the market

What "creating, strengthening and entrenching" means

The "substantial lessening of competition" test applied by the ACCC has been amended under the law passed to introduce the new regime, to make it clear that a substantial lessening of competition can be constituted by the creation, strengthening or entrenching of substantial market power.

While this is seen by some as an expansion of the SLC test, the ACCC's view is that it is intended to reflect the link between lessening competition and increased market power, clarifying – not changing – the test's meaning.

The guidelines provide that "the more market power one party already has, the more likely it is that a merger will entrench that market power and be a 'substantial' lessening of competition."

Practically, this is likely to increase the focus on mergers involving a party with a large market position – even if the change in market share or volume of sales brought about by the merger is minimal.

Platforms and Multi-sided Markets specifically considered

The guidelines recognise that mergers involving multi-sided platforms (eg. social media platforms) that supply services to two or more distinct, but related customer groups are generally analysed in a similar way to mergers involving differentiated products. However, the guidelines call out some specific considerations to these types of acquisitions:

1. The impact of the merger on "network effects"; that is, where the value of the product for customers on one side of the platform depends on the volume of users either on the same side or on the other side, and in particular where network effects are strong and create a "tipping effect" where one platform becomes "supreme" and small platforms only exert weak constraint;
2. The ACCC will consider each side of the platform a separate market for the purpose of its analysis and will consider the potential for unilateral effects on each side of the platform, both sides of the platform or overall competition between platforms.