United Kingdom - Market Insights

Has UK intervention risk dropped for global deals?

Although the UK operates one of the few voluntary merger control regimes globally, from 2018 until late 2024 the Competition and Markets Authority (CMA) stood out on the world stage as a highly interventionist agency. At the zenith of its interventionism between 2020 and 2022, the CMA referred around 30–40% of Phase 1 cases to in-depth Phase 2 investigation (before 2018/2019, Phase 2 referral rates were 10–20% of Phase 1 cases) and over 50% of deals referred to in-depth investigation were blocked or abandoned. Other commentators have noted the significant increase in the post Brexit period of intervention by the CMA in global transactions (most notably in US-to-US deals). Since early 2025, however, a tangible shift in approach from the CMA has altered the assessment.

Post-Brexit increased scope to act

Prior to Brexit, global deals typically fell within the EU merger regime’s “one-stop shop”, with UK merger control only applying where the European Commission did not have jurisdiction to act.

After Brexit, UK merger control could apply in parallel. The CMA took on its expanded jurisdiction with gusto even before Brexit took effect, with a notable rise in interventions in global deals, in particular a number of US-to-US deals, with no significant UK nexus. Ten deals were blocked, unwound or abandoned in 2019. Before 2018, the CMA typically intervened (meaning, in this context, Phase 1 remedies, a Phase 2 review ending in clearance or remedies, a prohibition or unwinding, or resulting in the deal being abandoned) in three or fewer mergers each year without a UK-headquartered party – never more than 25% of total interventions. During its most interventionist period in the five years between 2018 and 2022, there were 30 interventions in foreign-to-foreign mergers.

The height of controversy around CMA interventionism occurred when it initially blocked Microsoft’s acquisition of Activision Blizzard, which the European Commission had cleared with a behavioural remedies package that the CMA rejected and which a US court declined to injunct. Under political pressure and facing court review of its initial decision, the CMA cleared an alternative deal structure with conditions later in 2023.

The CMA also took a notably proactive approach towards the wave of strategic partnerships and investments by big tech firms in GenAI. Of the five deals called in for review in 2023–24, only one was found to be a “relevant merger situation”, but was cleared unconditionally. The CMA’s scrutiny was notably rigorous, with one review taking 15 months, only to be found (the day after the formal CMA clock started) not to qualify as a “relevant merger situation” after extensive requirements for disclosure of information and internal documents.

The CMA’s high-profile interventions in global deals, notably on Microsoft/Activision, fed complaints from business to the UK government about the burden and chill from CMA interventions.

Government pressure and the 4Ps

In January 2025, the Chair of the CMA was unexpectedly forced to step down, amidst significant government criticism of regulatory red tape hindering investment into the UK despite an urgent UK growth imperative. Regulators were put on notice to support the drive to grow the UK economy.

The CMA had anticipated this new approach to some extent with the announcement in late 2024 of its “4Ps” initiative to overhaul its procedures with greater “pace, proportionality, predictability and process”. Subsequent “4Ps” reforms have included:

• more engagement, updates and interaction with the case team and senior decision-makers at an earlier stage, with a new “Mergers Charter” setting out expectations on parties;
• shorter pre-notification processes with a key performance indicator (KPI) of 40 working days (which it has met since its introduction in June 2025);
• quicker Phase 1 clearance for straightforward mergers, with a KPI of 25 working days (again, which it has met since June 2025); and
• revised remedies guidance and a more open approach to more creative remedies including behavioural remedies at Phase 1.

By mid-February 2025, the government was praising the change in approach from the CMA. Legislative reforms have been announced to move CMA Phase 2 decision-making from a decision-making group that is independent of the CMA Board to a group comprising a majority of CMA executives. Reforms will also reduce the flexibility and unpredictability of elements of the jurisdictional tests, including the elastic “share of supply” jurisdictional test and the concept of “material influence” as a reviewable level of control.

Impact of the 4Ps in practice

The CMA’s focus on the 4Ps has tangibly reduced intervention levels. New procedural steps such as a “teach-in” from the parties (about the products, services and markets relevant to the transaction), regular informal updates and earlier involvement of senior officials, have resulted in greater pace and transparency about the areas of concern.

This shift can also be seen in the statistics. Phase 1 cases where significant concerns are identified will have a “case review meeting” (CRM) in the latter part of a Phase 1 review. Notably, the number of CRMs has significantly reduced with only seven in the 12 months to 31 March 2026, compared to 20 in 2024–25 and 32 in 2023–24. The lowest number of Phase 1 reviews in 20 years were opened in 2025–2026 (totalling 32, compared to 41 in 2024–25 and 54 in 2023–24, with only one previous year with fewer than 40 Phase 1 cases — 38 in 2020–21). The 2025 calendar year saw the lowest level of CMA interventions since the current merger legislation came into force in 2003.

More informal reviews?

In addition to formal reviews, the CMA conducts informal merger reviews through its Mergers Intelligence Committee (MIC), which scans for M&A activity in the UK as well as receiving information from complainants and through contacts with other antitrust agencies. It will often reach out to ask the parties about a non-notified merger.

Parties can also submit a short briefing paper to the MIC about a deal to explain why the CMA does not have jurisdiction and/or that there are no competition concerns. The MIC’s work is not publicised, but the CMA publishes annual statistics. The number of briefing papers submitted has increased to 217 in the 12 months to 31 March 2026 (from 187 in 2024–25 and 185 in 2023–24), at the same time that Phase 1 cases fell (see above). It is believed that high profile global deals including Mars/Kellanova and Google/Wiz were likely waved through on the basis of a briefing paper, as no formal Phase 1 review was initiated by the CMA.

Stepping back

Under the 4Ps initiative, the CMA will “step back” in global deals which do not have a particular UK nexus. This is manifesting in various ways.

The CMA will “wait and see” in relation to global deals where potential concerns affecting UK consumers may be fully addressed by remedies accepted in other jurisdictions. It encourages parties to discuss a wait-and-see approach with the MIC (when no KPI or statutory clock is running). The CMA has indicated that there were two (unnamed) wait-and-see cases in 2025-26, one of which was cleared elsewhere and the other was pending (as at late April 2026). 

If there were only two formal wait-and-see cases, “stepping back” may also come in other forms. In Subsea 7/Saipem, the UK restricted its review to issues on the UK Continental Shelf in the North Sea. It cleared the deal unconditionally in Phase 1, leaving concerns about impacts of the deal in deep sea offshore markets to other agencies. In Shutterstock/Getty Images, a Phase 2 investigation was launched on the basis of concerns in relation to both the UK market for editorial content and the global market for paid stock images. However, at Phase 2 the CMA accepted that generative AI was an increasing competitive constraint on the global supply of stock content and so narrowed its focus to the UK editorial market.

In Global Business Travel Group/CWT, both US businesses, the CMA initially identified significant competition concerns requiring remedies, even prohibition. However, two of the panel of decision-makers later changed their view and the deal was cleared unconditionally. At the time, the US Department of Justice was suing to block the deal (later dropped).

However, the statistics for intervention in foreign-to-foreign mergers have not settled back to pre-2018 levels. As noted above, deals without a UK-headquartered party accounted for no more than 25% of the CMA’s interventions before that date. In 2025, they still accounted for some 50% (although based on a reduced case load).

Issues for the UK will still get close attention

As the statistics show, the CMA has not stepped back completely where a global deal raises issues for UK consumers. As noted, Shutterstock/Getty Images was sent to Phase 2 and the CMA cleared the deal on the condition that the companies sold Shutterstock’s global editorial business. Getty subsequently decided not to proceed with the merger. The deal was cleared unconditionally in the US without an in-depth second request process. In Aramark/Entier, the CMA ordered the unwinding of the completed acquisition by a US business of a UK offshore catering business serving customers on the UK Continental Shelf (but has allowed Aramark to retain the Australian part of Entier). In Vandemoortele/Délifrance, the CMA was moving towards accepting a Phase 1 divestment remedy with an upfront buyer, mirroring remedies already accepted by the European Commission. However, because no upfront buyer had been secured before the deadline, a Phase 2 investigation was launched. 

Managing CMA intervention risk

In deciding whether to approach the CMA for a global transaction, with formal notification, a briefing paper, or not at all, the following practical points should be factored into the decision, in light of the new approach from the CMA:

• Is there a direct and distinct impact on UK consumers as a result of the transaction? The CMA has said that where the parties consider there is not, they should explain why in a briefing paper to the MIC.
• Is this a straightforward “no overlap” case or are there plausible theories of harm (horizontal, vertical or conglomerate)?
• Can the competitive “story” be told convincingly in five pages or does it involve detailed economic or local markets analysis? Complex analysis would indicate that a full notification would be more appropriate than a briefing paper.
• What is the deal timetable and how would a CMA review interact with other jurisdictions?
• If the deal does raise substantive competition issues, is the deal being reviewed by other regulators where remedies might address UK concerns (e.g. a deal being notified in the US or EU and remedies are likely to be global in scope)? A briefing paper proposing a wait-and-see approach may be appropriate.
• Can closing be made conditional on the CMA’s response? Conditions can be structured around receipt of “no further questions” confirmation from the MIC. If the SPA contains a springing CMA condition (i.e. CMA consent is required as a condition to closing only if the CMA calls in a transaction for formal Phase I notification and review prior to closing), the parties can submit a briefing paper while managing the risk of a post-completion call-in.