The ACCC has released a report detailing the findings arising from reviews of six mergers which occurred between 2017 and 2019, that were not opposed by the ACCC.

Reviews of past merger decisions (often referred to as ‘ex post’ merger reviews) are undertaken by competition authorities around the world to inform and improve processes and decision making.

“Examining how a merger played out over time allows us to test whether the assumptions, evidence and economic theories on which we based our decisions were sound,” ACCC Chair Rod Sims said.

“The findings will inform current and future merger reviews and analysis, allowing us to further refine and improve our work.”

Mergers examined in the report include Caltex’s acquisition of Milemaker, Emergent Cold’s acquisition of AB Oxford Cold Storage Company and Winc’s acquisition of OfficeMax, among others.

The mergers reviewed were not opposed by the ACCC at the time. This means that at the time and with the information and evidence before it, the ACCC did not consider the proposed mergers would be likely to substantially lessen competition in any market, which is the test the ACCC must apply.

“The findings were mixed. Some confirmed the predictions made by the ACCC at the time of the decision played out broadly as expected, while others highlighted instances where the forecasts and assumptions made during the original review did not always hold up with time,” Mr Sims said.

“We also know now that in some cases we did not receive complete information during our reviews. Concerningly, there were instances where merger parties and other stakeholders appeared to distort or omit critical information relevant to the ACCC’s analysis.”

“This highlights the weaknesses in the current informal clearance regime, whereby merger parties effectively decide how much and what type of information they provide upfront to the ACCC,” Mr Sims said.

“We routinely need to request base level information or negotiate for further information often under time constraints and, in some cases, while the parties are threatening to complete the merger before the ACCC has reached a view.”

“We continue to call for reforms to the merger regime in Australia which includes the introduction of a mandatory notification regime, to improve the effectiveness of merger control in Australia and bring it into line with international best practice,” Mr Sims said.

One important issue highlighted by the review is the need for greater scrutiny of claims from merger parties that new market entrants, or customers’ bargaining power, can provide sufficient competition to newly merged entities.

“Based on the findings from the reviews, we are implementing changes, including in how we assess economic arguments put to us and other evidence,” Mr Sims said.

The ACCC is continuing to review other past merger decisions and will publish any findings of interest.

The report can be found on the ACCC’s website here: Ex post review of ACCC merger decisions


The ACCC is responsible for enforcing the Competition and Consumer Act. Section 50 of the Act prohibits mergers that would have the effect, or be likely to have the effect, of substantially lessening competition in a market.

In October 2021, Mr Sims gave a speech outlining challenges in Australia’s merger regime: Competition in Australia faces big challenges