The CMA's 4Ps Mergers Reform: Are Promises Turning Into Practice?

Over the past year, the UK Competition and Markets Authority (CMA) has made repeated commitments to reform its mergers work based on the "4Ps" (pace, predictability, proportionality and process) framework. In recent months, those promises have begun to take shape, through a number of substantive policy outputs and operational changes which have practical implications for dealmakers. This post examines recent developments, how the CMA is delivering on its 4Ps commitments, and what they mean for UK-facing transactions in the months ahead.

A recap of recent changes

Last month, the CMA finalized updates to its mergers jurisdictional and procedural guidance (CMA2), which formalizes several process changes that have been trialed throughout 2025. These include:

• A more formal and structured pre‑notification process, including:
  • A new KPI to complete pre‑notification within 40 working days (WD);
  • A public invitation for market feedback as a matter of course; and
  • Enhanced engagement with CMA case teams.
• A target to clear 'straightforward' Phase 1 cases more quickly (by working day 25, rather than 35).
• Clarifications to the 'material influence' and 'share of supply' jurisdictional tests.
• Details on how the CMA's previously trailed 'more proportionate approach' to reviewing global mergers will be implemented.

The CMA also published draft revisions to its Merger Remedies Guidance for consultation, following a March call for input. The draft guidance signals more flexibility on the types of remedies the CMA may accept, clearer routes to Phase 1 solutions, and a commitment to preserve efficiencies and customer benefits where credible and verifiable.

A more business‑friendly process?

The most tangible changes seen to date relate to process. In March 2025, the CMA's new Mergers Charter pledged early and more direct access to decision‑makers, with regular update calls with case teams. The new CMA2 guidance delivers on this promise by building enhanced engagement into the CMA's merger reviews, including:

• An invitation for merger parties to provide a 'teach-in' session in the early stages of pre-notification.
• Informal update calls during pre-notifications to hear the case team's current thinking and an overview of third-party feedback.
• The option for earlier without prejudice discussions on remedies.

The CMA has also stated that it will be more focused and targeted when information gathering, meaning that "merger parties will be required to produce a reduced volume of internal documents and/or respond to fewer questions in requests for information – targeted at key potential competition concerns".

Our experience shows that these changes are already making a meaningful difference in live cases, with improved engagement with CMA case teams compared to recent years. In practice, this gives merging parties earlier visibility of – and therefore the ability to address – potential issues and the opportunity to consider remedial solutions, where required.

Will the UK regime be more predictable?

A lack of transparency on the CMA's emerging thinking has oft been cited as contributing to the unpredictability of the UK merger review process. The CMA has clearly listened to business feedback on this issue and responded. Beyond this, however, it remains to be seen whether the other major source of unpredictability affecting the UK regime – namely the CMA's flexible approach to asserting jurisdiction – will see meaningful reform.

In this respect, the updated CMA2 guidance offers some clarifications on how the CMA will apply the material influence and share of supply tests. However, the changes do little more than confirming the CMA's recent decisional practice, whilst the CMA retains its discretion to adopt a different approach where it sees fit. This is perhaps unsurprising, as the CMA does not have the power to amend the jurisdictional tests as set out in UK legislation.

The UK Government is expected to consult on potential legislative reforms to more tightly delimit the CMA's jurisdictional powers in the near future. Until this happens, greater predictability will only come from the CMA's willingness to apply a consistent framework in practice and avoid the expansive approach seen in previous cases, such as Facebook/Giphy, Sabre/Farelogix and Roche/Spark Therapeutics.

Is the CMA delivering on pace?

Review timelines are showing early signs of improvement. In particular, the CMA's more streamlined approach is yielding shorter, more concise Phase 1 clearance decisions, with several cases being approved within 25 – 30 working days (down from a previous average of ~35 working days). Although only a few mergers that have been approved within the new 25 day target for straightforward Phase 1 clearances, this is to be expected since the most 'straightforward' cases do not in fact undergo formal review, given the voluntary nature of the UK regime.

The new 40 WD KPI also promises to materially compress pre‑notification, a phase that has historically drifted. However, there are important caveats:

• The KPI clock starts only once a sufficiently complete draft Merger Notice and supporting documents (including internal documents) are in the CMA's hands. This risks a 'two-stage' pre-notification, with most of the information gathering completed by the CMA before the 40 WD period for the new KPI begins. Unless managed carefully, this approach risks shifting the documentation burden earlier in the process without reducing overall timelines.
• The CMA reserves the right to suspend the 40 WD KPI if it considers parties are not engaging consistently with the Mergers Charter.
• For complex cases, the revised CMA2 guidance is less impactful, and timelines will remain contingent on the depth of information‑gathering and third‑party testing the CMA considers necessary.

Whether the new approach consistently reduces overall timelines remains to be seen. In the meantime, the changes clearly encourage and reward disciplined preparation and proactive engagement with the CMA from day one.

Is proportionality realigning outcomes?

Improving the proportionality of the UK regime has two important dimensions, namely avoiding unnecessary or overly burdensome investigations, and enabling deals with competition concerns to be cleared with effective remedies whenever possible.

'Wait and see' approach to global mergers

The CMA's willingness to prioritize investigating deals which have a UK-specific impact is intended to avoid unnecessary or duplicative reviews of global deals where any remedies imposed or agreed in merger control proceedings in other jurisdictions would likely address any competition concerns in the UK.

The new CMA2 guidance explains that, in circumstances where a deal that exclusively concerns global (or broader than UK) markets could reasonably raise substantive concerns, the CMA's mergers intelligence function may inform the parties that it intends to 'wait and see' the progress of proceedings in other jurisdictions, before deciding whether a UK investigation is warranted. In such cases, the CMA would request updates on those proceedings as well as appropriate waivers to directly discuss with the reviewing authorities.

While the intent is welcome, this approach may not be sufficiently reliable in practice due to the risk of late stage intervention, particularly where remedies agreed elsewhere are deemed insufficient to resolve UK concerns. The Shutterstock/Getty deal – a global merger between two US companies operating in digital markets – demonstrates that the CMA will not be taking a back seat on all global deals. Despite ongoing review by the US Department of Justice, the CMA recently referred the deal for an in-depth Phase 2 review due to concerns voiced by UK stakeholders, having rejected remedies proposed by the parties.

As such, it remains to be seen how often either the CMA or merging parties will be willing to take their chances on the new 'wait and see' approach.

Revised remedies guidance offers greater flexibility

The draft updated Merger Remedies Guidance seeks to deliver on the CMA's earlier promise that less-straightforward deals should always be cleared conditionally (and not unduly pushed into protracted Phase 2 processes or prohibition) whenever effective remedies are possible.

The CMA is looking to achieve this, in particular, by clarifying and broadening the circumstances in which behavioural remedies and more complex divestments/carve-outs may be accepted, including at Phase 1. The draft guidance also provides more clarity on the evidentiary requirements which merging parties will need to meet to have such remedies approved. As noted in our previous post, this reflects the CMA's greater openness to non-structural remedies in practice in recent cases, including Vodafone/Three UK and SLB/ChampionX.

Whilst the standard remedy requirements of effectiveness, monitorability and enforceability will continue to apply, the new direction of travel is towards more pragmatic outcomes, sooner, whenever credible packages are on offer. However, the draft guidance stresses that early, in-depth engagement with the CMA, ideally with support from independent experts (e.g. trustees) in more complex cases, will be key in ensuring successful outcomes. Without such engagement, the CMA's traditional skepticism towards complex remedies can be expected to continue (in referring Shutterstock/Getty to Phase 2 the CMA emphasized that the parties had "offered a complex package of remedies at a late stage in the Phase 1 process", which failed to address its concerns).

Further reforms imminent?

As noted above, the UK Government is expected to publish proposals for legislative reforms in the coming weeks. In addition to potential changes to the CMA's jurisdictional powers, the Government has previewed plans to replace the CMA's panel model for decision-making in Phase 2 cases.

The panel system is a legacy from the period when the CMA's functions were split between two independent bodies (the OFT and Competition Commission). Under the current proposal, this would be replaced with a board committee model, effectively bringing Phase 2 decision-making 'in-house' within the CMA. This proposal would bring the CMA in line with its European peers, but has raised a few eyebrows, due to concerns that such changes might affect the CMA's independence (which both the CMA and the Government have been quick to downplay).

In addition, the CMA Interim Chair has indicated that the CMA is considering a suite of additional KPIs to measure the CMA's direct and indirect impact, how efficient its operations are, and how it engages with stakeholders. To support this, CMA will be launching two stakeholder surveys in the coming months, aimed at further strengthening the CMA's engagement with the business community.

Bottom line: promising progress, sustained delivery required

The CMA's willingness to engage with external stakeholders on merger reforms and the speed at which the CMA has sought to identify and implement new ways of addressing long-standing challenges has been widely welcomed. However, whilst UK merger control is evolving, it remains far from straightforward. The CMA's 4Ps mergers reforms are beginning to take shape, with clearer guidance and more structured processes now in play, but it is still early days and ultimately consistency is what will drive real change. What is clear is that opportunities for effective engagement with CMA case teams are improving. As such, getting the engagement strategy right from the very beginning, especially in more complex cross-border deals, will remain key while these updates settle into practice.

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