UK merger control: growing uncertainty for dealmakers

August 2026  |  FEATURE | MERGERS & ACQUISITIONS

Financier Worldwide Magazine

August 2026 Issue

In an increasingly scrutinised regulatory environment, merger control in the UK has become a critical consideration for companies pursuing growth through acquisitions, consolidation or strategic investment. The Competition and Markets Authority (CMA) is adopting a more assertive approach to deal assessment, with heightened focus on competition concerns, consumer impact, innovation and strategic interests. Businesses must navigate evolving thresholds, longer review processes and greater uncertainty, particularly in complex sectors.

This shift has become more pronounced in 2026, with the government launching a consultation on changes to the UK’s merger control and markets regimes. The consultation, which closed in March 2026, formed part of a broader effort to drive economic growth and ensure the UK operates a ‘best in class’ competition regime. Many of the proposals are likely to increase predictability and transparency, although some remain controversial, particularly the proposal to abolish the CMA’s panel-based decision-making process.

An increasingly interventionist CMA

For Paolo Palmigiano, a partner at Winston Taylor, the CMA’s increasingly interventionist stance has made merger control a central element of UK M&A strategy. “Businesses are assessing competition risk much earlier, often before valuation and transaction structures are finalised,” he says. “Parties are building longer timelines into deals. Although notification remains voluntary, the CMA’s willingness to investigate completed transactions has effectively made engagement unavoidable in many cases. As a consequence, we have seen increased use of briefing papers submitted to the CMA at an early stage to seek informal comfort and greater regulatory certainty.”

According to Christopher Eberhardt, a partner at Ashurst, the updated, pro-growth, strategic steer issued by the UK government in May 2025 has led the CMA to pivot toward a more business-friendly approach. “This has seen the CMA emphasise more proportionate and targeted interventions, as well as faster reviews, in line with its ‘4Ps’ framework – ‘pace’, ‘predictability’, ‘proportionality’ and ‘process’,” he notes.

The 4Ps framework is intended to make investigations faster, more transparent and less burdensome while preserving robust competition oversight. Elements of the framework have now been incorporated into updated CMA guidance and procedures.

The framework has generally been welcomed by businesses, investors and legal advisers as a recognition that regulatory uncertainty and lengthy investigations can inhibit dealmaking and investment. Supporters argue that clearer procedures and more proportionate enforcement could enhance the UK’s attractiveness as a destination for capital and strategic transactions.

However, it has also attracted criticism, with some observers arguing that tangible structural reform remains limited and questioning whether greater ‘pace’ could come at the expense of analytical depth in complex cases.

Regardless of how the 4Ps are received, UK merger control is evolving and creating uncertainty for dealmakers, particularly around jurisdictional thresholds, review timelines and enforcement risk.

Jurisdictional uncertainty and procedural complexity

“Notwithstanding the proposed Competition Reform Bill, designed to speed up competition and merger decisions and make the regime more pro-growth, substantial uncertainty still arises from the expansion of the CMA’s jurisdiction and the unpredictability of review processes,” observes Mr Palmigiano. “The Digital Markets, Competition and Consumers Act 2024 introduced new thresholds aimed at large businesses with substantial UK market positions. At the same time, the CMA’s broad interpretation of the ‘share of supply’ test continues to create uncertainty around whether transactions fall within jurisdiction.

“Review timelines also remain difficult to predict, particularly given recent changes to the merger process, which are likely to lengthen already extensive pre-notification discussions,” he adds.

For Mr Eberhardt, the ‘wait and see’ approach – deferring to other regulators where markets are global and UK-specific issues are likely to be addressed elsewhere – has gained prominence, although its application remains uncertain. “The CMA’s greater willingness to consider behavioural remedies is welcome, though it remains relatively untested,” he says. “On jurisdictional thresholds, the DBT consultation and the Competition Reform Bill suggest there may not be significant changes in practice, meaning the CMA is likely to retain considerable discretion.”

One area where the CMA has adopted a more interventionist approach is in the technology, healthcare and infrastructure sectors. It has shown greater willingness to scrutinise digital ecosystems, data access and innovation concerns, creating particular challenges for dealmakers.

When responding to this shift, proactive engagement is essential. “Parties should engage early with the CMA, particularly if a transaction may benefit from the ‘wait and see’ approach, where parallel international reviews are underway,” suggests Mr Eberhardt. “Earlier substantive engagement, such as through teach-in sessions or discussions around potential remedies, can also help to shorten timelines.

“In technology markets, the CMA is scrutinising acquisitions involving data, digital ecosystems and emerging competitors, particularly where there are concerns around ‘killer acquisitions’ or market entrenchment,” suggests Mr Palmigiano. “In healthcare, the CMA is paying closer attention to pipeline products, research and development capability, and long-term innovation incentives. Overall, the CMA’s approach reflects a broader focus on preserving future competition, consumer choice and national economic resilience in strategically important sectors.”

Recent CMA activity highlights these trends, with cases demonstrating its willingness to scrutinise transactions and intervene where necessary. In the coming months, companies and investors will need to approach UK merger control proactively and assess regulatory risk early in the transaction process.

As the UK seeks to balance competitiveness with enforcement, the CMA faces pressure to deliver merger control that is both rigorous and commercially pragmatic. Its handling of complex transactions is likely to remain a defining feature of the regulatory environment.

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Richard Summerfield