The Rules Are Changing: European Merger Control at a Crossroads

Introduction

A striking paradox has emerged in European competition enforcement: regulators are simultaneously casting an ever-wider net over transactions including those falling outside traditional merger control thresholds, whilst consulting on approaches that promise greater flexibility and openness to the benefits of consolidation. This tension reflects current market realities. On one hand, there is rapid consolidation across certain sectors and, in some areas, calls for the promotion of larger European players capable of competing on the global stage. On the other, authorities want to protect smaller innovators from being absorbed or marginalised. In this context, competition law, and especially merger control, has come under criticism for being out of date and ill-equipped to deal with modern markets. In response, both the European Commission ("Commission") and the UK Competition and Markets Authority ("CMA") have been adapting and updating their approaches.

This Legal Update examines three critical developments that exemplify this paradox: (i) the evolving approach to below-threshold transactions; (ii) the ongoing scrutiny of non-controlling minority shareholdings; and (iii) the modernisation of merger guidance, including more flexible approaches to efficiencies and remedies. Whilst the first two themes illustrate how authorities are ensuring no potentially problematic conduct escapes their reach, the third demonstrates how regulators are seeking to balance concerns about overreach with more pragmatic analysis. All three areas present both challenges and opportunities for dealmakers, but the overriding message is clear: the rules of engagement are shifting, and businesses should plan their deal strategy accordingly.

1. Below-Threshold Transactions: The Expanding Reach of Competition Enforcement

The first illustration of authorities extending their reach concerns transactions that fall beneath traditional notification thresholds. Such deals may be perceived as problematic by competition authorities, especially when they involve a large player acquiring smaller strategic targets, potentially giving rise to significant competition law risks.

In the United Kingdom, the Digital Markets, Competition and Consumers Act specifically amended the UK merger control regime to target killer acquisitions, introducing a new jurisdictional threshold applicable to such deals. In the European Union, since the landmark ruling in Illumina/Grail, the Commission has been encouraging national competition authorities ("NCAs") to amend their merger control provisions to introduce targeted "call-in" powers or consider the use of behavioural rules to catch these kinds of transactions and address a perceived enforcement gap. Some jurisdictions, such as Italy, have revised their thresholds, while others, which have not yet done so, such as France and Belgium, but in the meantime are increasingly adopting an ex-post antitrust assessment, reviewing below-threshold transactions through the lens of abuse of dominance or anticompetitive agreements. In other words, competition authorities are demonstrating that antitrust powers can be deployed to challenge already closed transactions.

The French Competition Authority used antitrust powers in 2024 to assess a series of cross-divestitures in the meat-cutting sector under Article 101 TFEU. Acquisitions presenting indicia of collusion, such as market allocation through cross-sales or exchange of commercially sensitive information during negotiations, could be considered illegal if there is an anticompetitive purpose and discussions are not part of preparations for the merger agreements.

The French Competition Authority took a further step in 2025, imposing its first fine on a below-threshold acquisition using Article 102 TFEU. It concluded that Doctolib allegedly abused its dominant position by acquiring its closest rival seven years earlier, on the ground that the acquirer's intent was to remove competition from the market. Importantly, mere strengthening of dominance is not abusive; authorities must demonstrate that, post-transaction, the remaining players on the market will be dependent on the acquirer. This decision is currently under appeal.

In Belgium, the NCA has opened antitrust investigations deals where they have been publicly announced but not yet closed, intervening with interim measures such as hold-separate orders imposed to prevent integration. This effectively converts ex-post antitrust powers into a de facto ex-ante review.

While the use of interim measures mitigates some of the strains of post-closing intervention, dealmakers must factor regulatory intervention risk into transactions that, until recently, would have proceeded without a second thought. This approach of employing behavioural rules to in effect review mergers, notwithstanding legal thresholds not being met, fundamentally alters the risk calculus for dealmakers, who can no longer assume that clearing traditional thresholds guarantees regulatory peace.

In this context, it is important to note that the French Competition Authority may soon be able to allocate more resources to monitoring below-threshold transactions, as a recently adopted bill increases the French monetary thresholds (which had not been updated for more than 20 years). This change will naturally result in fewer notifiable transactions. The UK Government is currently analysing feedback after consulting on steps to increase certainty for dealmakers by tightening up the criteria the CMA can use for applying the share of supply test to establish jurisdiction to review a merger. This jurisdictional threshold has, in the past, been applied in ways which might have surprised businesses, creating uncertainty about which transactions may fall within the CMA's remit. Clarifying these criteria should provide greater predictability for parties assessing their notification obligations, at least in the United Kingdom.

The authorities' determination to leave no potentially problematic transaction beyond their reach extends to non-controlling minority shareholdings, where traditional merger control frameworks have historically provided limited oversight.

2. Non-Controlling Minority Shareholdings: Another Avenue of Extended Scrutiny

Acquisitions of non-controlling minority interests will typically escape merger control but can still give rise to significant competition law risks. The Commission has for many years made clear that a minority stake should not serve as an instrument for influencing a competitor's commercial conduct. Critically, the lack of control does not entitle parties to benefit from intra-group antitrust immunity, as illustrated by the Commission's EUR 329 million fine in Delivery Hero/Glovo for misuse of a minority stake (as low as 15%) to foster collusion. More recently, in Naspers/Just Eat Takeaway, the Commission required Naspers to divest a significant part of its 27% non-controlling stake in Delivery Hero, a direct competitor of Just Eat Takeaway it contemplated to acquire.

The Commission's March 2026 Merger Brief confirms that even absent formal control, governance rights such as board seats or approval rights over investment rounds may allow a minority shareholder to influence a competitor's strategic decisions. The Commission will examine structural links between competitors looking beyond formal thresholds to assess practical influence. For dealmakers, this means that traditional legal categories (control versus non-control, notifiable versus non-notifiable) are becoming less reliable guides to regulatory exposure.

3. Modernisation of Merger Guidelines: The Flexibility Counterbalance

If the first two developments illustrate how authorities are expanding their enforcement reach, the third represents the other side of the paradox: a move towards greater flexibility and recognition of the benefits of consolidation. The Draghi Report suggested that European competition policy has prioritised protecting smaller firms over enabling European companies to achieve the scale necessary to compete globally. Similarly, in the United Kingdom, the Labour government has raised concerns about the CMA's approach and its potential effects on economic growth. In response, both the Commission and the CMA have published consultations on modernising their merger control regimes.

EU Developments

In the European Union, the Commission's review of its merger guidelines arguably represents the most significant overhaul of EU merger control in over two decades. A key consideration underlying this revamp is the acknowledgement that European companies must be allowed to scale up to compete globally, with consolidation across national boundaries creating so-called "EU champions." However, the Commission is wrestling with what constitutes "positive scale", a novel concept, and the potential adverse effects of heightened concentration versus positive externalities such as productivity gains, cost rationalisation, and enhanced ability to invest and innovate. In this context, key areas to be reflected in draft guidelines include productivity and innovation in the single market, sustainability, and the cost of living and price effects of mergers.

UK Developments

In the United Kingdom, on 15 January 2026, the CMA launched a review of its approach to assessing "rivalry-enhancing efficiencies" in mergers, marking a potentially significant shift in how the regulator considers efficiency arguments. This consultation follows significant reforms to UK merger control over the past year, including December 2025 remedies guidance signaling greater openness to behavioural remedies and acknowledging that remedies can be used to "lock in" pro-competitive efficiencies. These reviews conducting by the CMA form part of its "4Ps" framework (pace, predictability, proportionality, and process), aimed at supporting growth, investment, and business confidence in the United Kingdom. Central to the CMA's efficiencies consultation is stakeholder input on the CMA's analytical approach to how dynamic efficiencies (relating to future innovation and investment) are assessed, and the process for engaging with merging businesses wishing to raise efficiency arguments. Interestingly, the CMA is also interested in clarifying the types of evidence relevant to efficiency assessments. Both the Commission and the CMA have stressed that merger assessments must be grounded in rigorous, evidence-based decision-making, with outcomes determined on the basis of all relevant circumstances of each case. Rather than applying rigid presumptions, regulators are signalling a willingness to engage substantively with the facts, weighing the specific competitive dynamics, market conditions, and efficiency claims presented by the parties. This case-by-case approach reflects a broader commitment to analytical flexibility and proportionality in merger enforcement.

Looking ahead, results from both consultations are awaited, but the stakes are high, potentially ushering in a new generation of merger assessment including what remedies are considered acceptable. The timing of the new EU draft guidelines coincides with the appointment of Anthony Whelan as the new head of DG Competition in April 2026, who has immediately promised increased "openness" and "clarity" in EU merger reviews. The current period of transition creates both risk and opportunity: those who engage proactively with the evolving framework may find regulators more receptive than in the past, whilst those who continue to rely on established but outdated practices risk facing adverse regulatory outcomes.

Key Takeaways

The common thread running through these developments is that the familiar landmarks of merger control are shifting. Dealmakers who have relied on established thresholds, structural presumptions, and traditional remedies frameworks must recalibrate their approach. The following points should guide transaction planning in this period of flux:

• Thresholds no longer define enforcement boundaries. Below-threshold deals face scrutiny under behavioural rules, whilst non-controlling minority stakes attract attention through analysis focused on governance and day-to-day interactions. Any transaction involving a player with significant market presence, whether a full acquisition or a minority investment, may attract regulatory intervention across multiple jurisdictions, regardless of whether traditional notification thresholds are met.
• Navigate the current merger enforcement paradox strategically. Regulators are simultaneously expanding their reach and signaling greater openness to consolidation benefits. Dealmakers should document procompetitive rationales from day one including synergies, efficiencies, and consumer benefits whilst also preparing for the possibility of regulatory challenge. Internal documents are increasingly central to assessments, so ensure they articulate rivalry-enhancing efficiencies and out-of-market benefits clearly and in good time.
• Treat information barriers as essential. Clean teams, strict protocols, and board nominee compliance training are critical safeguards against allegations of anticompetitive coordination and because regulators now examine structural links between competitors for evidence of practical influence including on the basis of information flows, even where formal control is absent.
• Watch this space. A lighter-touch, pro-growth enforcement environment may be emerging but the direction and pace of change remain uncertain. Dealmakers should monitor developments closely as both the Commission and the CMA refine their approaches. Proactive engagement with new approaches is essential.

Mayer Brown's European Antitrust & Competition team comprises lawyers with a thorough knowledge of EU and UK merger and antitrust laws as well as procedures. We have extensive experience of dealing with enforcers at the national and EU levels. Please reach out to us to discuss any of the issues summarised above in more detail.