The second alert in the Dentons Merger Control Summer Series takes a deep dive into recent jurisdictional issues in merger control across Europe. We explore how regulators are tackling "killer acquisitions" (and "serial acquisitions") and what this means for legal certainty in dealmaking, with a spotlight on recent developments in the EU, Netherlands, Belgium, France and the UK.

EU developments

The Commission has suggested that killer acquisitions are one of the most "critical competition challenges that we face today". These below-threshold transactions are particularly prevalent in dynamic sectors such as life sciences and digital technologies.

Following the Illumina/Grail judgment (see analysis in our September 2024 alert here), the Commission was obliged to accept that it does not have jurisdiction to review below-threshold transactions where the member states' NCAs are unable to review a deal under their national merger control regimes.

The Commission is therefore exploring a number of alternatives to enable it to plug this enforcement gap. To this end, in its 2024 annual report on competition policy, the European Parliament called on the Commission to: (i) encourage member states to introduce so-called "call-in" powers (expanding the member states' jurisdiction) and refer such call-in situations to the Commission under Article 22 of the EU Merger Regulation (EUMR); and (ii) consider the possibility of amending the EUMR to enable the review of mergers below EU and/or national merger control thresholds.

Call-ins: the future of below-threshold merger control?

A significant number of NCAs (including Denmark, Hungary, Italy, Ireland Latvia, Lithuania, Slovenia and Sweden) already have the power to call in below-threshold transactions for review. Additionally, several member states are in the process of obtaining such call-in powers, including the Netherlands, France and Belgium – see further below.

The legality of calling in a below-threshold transaction and subsequently referring it under Article 22 EUMR was tested in October 2024, when the Commission stated that it would be reviewing the Nvidia/Run:ai transaction. While the transaction did not meet Italian merger control turnover thresholds, the Italian NCA made use of its call-in powers to refer it to the Commission, who unconditionally cleared the transaction. Nonetheless, Nvidia objected to the Commission's review of the transaction on the basis that it did not meet national turnover thresholds. The appeal is currently pending before the General Court. Nvidia is arguing, in particular, that the exercise of the Article 22 EUMR referral mechanism, based on the discretionary Italian call-in power, does not deliver the legal certainty required post Illumina/Grail.

In practice, therefore, where a transaction falls below both EU and national thresholds, it may still be prudent for merging parties to conduct an initial substantive competition analysis at an early stage in the deal process, in order to assess (and mitigate) the risk of future referral to the NCAs (and subsequently to the Commission), particularly in sectors such as life sciences and digital technologies. However, with only limited guidance on how national authorities will/should use their call-in and referral powers, dealmakers in dynamic and nascent markets are not in a position to diagnose or minimise this risk entirely.

The case for legislative change?

An alternative solution to addressing killer acquisitions would be for the Commission to lower current merger control thresholds in the EUMR, or even introduce a brand-new threshold based on transaction value as is in place in Austria and Germany. While such changes would have the benefit of increasing predictability and legal certainty for dealmakers, it could lead to a potentially significant increase in notifiable transactions which do not raise any competitive concerns. Such an increased burden on (EU) businesses would run contrary to Mario Draghi's report on EU competitiveness, which called for swifter and more streamlined merger control. Alternatively, as put forward by outgoing Competition Commissioner Margrete Vestager at the end of last year, the EUMR could be amended to introduce a "safeguard" mechanism, enabling the Commission to directly call in mergers falling below EU thresholds for review.

Recently, Commission officials have informally indicated that there may be no other choice than to "open up" the EUMR in the medium to long term in order to plug this enforcement gap, given the complexity and uncertainty of the current national call-in risk for dealmakers. The Commission may also consider seeking to align member states' powers in this area, although this would likely be problematic in practice, not least because the Commission is said to have informally encouraged the current "patchwork" approach. For the time being, scrutiny of below-threshold transactions at EU level is only possible if NCAs have jurisdiction to conduct these reviews.

Are other (competition) powers the answer?

In the Towercast ruling, the ECJ confirmed that NCAs can potentially investigate transactions under the abuse of dominance framework (Article 102 TFEU) if they are not caught by merger control regimes, as in the recent cases in the Netherlands and Belgium discussed below. For a detailed analysis of the Towercast ruling, see our previous alert here. In addition, the EU Digital Markets Act (DMA) requires large digital platforms designated as "gatekeepers" to report all transactions to the Commission, including those falling below relevant turnover thresholds. Arguably, this does not provide the Commission with an independent power to review such reported transactions and, following Illumina/Grail, there may be reduced scope for the Commission to make full use of it.

In addition, the EU Digital Markets Act (DMA) requires large digital platforms designated as "gatekeepers" to report all transactions to the Commission, including those falling below relevant turnover thresholds. Arguably, this does not provide the Commission with an independent power to review such reported transactions and, following Illumina/Grail, there may be reduced scope for the Commission to make full use of it.

Spotlight on the Netherlands

The Dutch Competition Authority (ACM) has recently been pushing for additional market intervention instruments, focusing on two key proposals: the introduction of a New Competition Tool (Competition Tool) and the granting of a call-in power. While the implementation of the Competition Tool, similar to the UK's "market investigation" powers, is not currently on the political agenda, the consultation on amendments to the Dutch Competition Act, aimed at incorporating the ACM's desired call-in power, has already concluded.

The proposed call-in power would allow the ACM to demand additional information from the companies involved in mergers (where the "standard" turnover thresholds have not been exceeded) and, upon review of that additional information, require a formal notification of the transaction if competition risks appear substantial. Following notification, the ACM would, as usual, be able to block the transaction or only allow it under certain conditions. To ensure compliance, the ACM would also retain the power to dissolve mergers if parties proceed without prior approval.

Intervention would need to be requested by the ACM within (the shortest of) one of three windows: (i) four weeks from the public announcement of a deal; (ii) four weeks from the ACM's discovery of the transaction; or (iii) six months after completion of the transaction.

Following the consultation, the ACM proposed a package of measures designed to balance effective market oversight with business certainty. These include raising the standard turnover thresholds to focus intervention on transactions of genuine competitive significance; introducing an asymmetrical turnover threshold specifically for call-in purposes (meaning that just one of the parties (usually the buyer) needs to meet a certain level of turnover); and publishing comprehensive procedural guidelines to ensure transparency and predictability in the ACM's decision-making. Together, these reforms aim to equip the ACM with the flexibility needed to tackle emerging competition concerns while safeguarding the legal clarity and administrative efficiency that businesses require.

However, some commentators take the view that the new powers would be redundant because the ACM is already reviewing mergers that fall below the standard turnover threshold, as evidenced by the fact that it recently launched an investigation on the basis of the Dutch equivalent of Article 102 TFEU into a (below-threshold) transaction in the sector for cash-in-transit services.

In addition, after receiving a notification from Foresco in 2024 relating to a transaction in the pallets sector that exceeded the thresholds, the ACM carried out a review into Foresco's broader acquisition strategy, meaning that multiple (non-notifiable) transactions were included.

It remains to be seen how the proposals will evolve as the legislative process advances, and what impact this will ultimately have on deal-making strategies and risk assessments across the M&A landscape. In the meantime, staying abreast of these developments will be essential for navigating M&A risks and structuring transactions with confidence. Given the recent reappointment of Martijn Snoep, a strong advocate of the new call-in power (and the Competition Tool), as the ACM's chairman, it is clear that the debate over these powers is far from settled.

Spotlight on France and Belgium

Both the French Competition Authority (FCA) and the Belgian Competition Authority (BCA) have called for the introduction of a "call-in" power.

France

In 2017 and 2018, the FCA launched specific consultations to assess the need for a tool to address mergers falling below notification thresholds. While the introduction of such a tool was ruled out, the Illumina/Grail judgment revived this debate and the FCA opened a public consultation in January 2025 in which it presented three options for addressing this topic:

• Option 1: The implementation of a call-in power for the FCA based on quantitative and qualitative criteria (turnover threshold, impact on the French territory, risk of significantly harming competition and limited period of time for the FCA to order the parties to notify the transaction after its completion).
• Option 2: The introduction of an obligation to notify if (i) one of the parties has been the subject of a merger control prohibition decision or a clearance decision subject to commitments, (ii) one of the parties has been fined or has accepted commitments in relation to anti-competitive practices, or (iii) one of the parties to a merger has been designated as a gatekeeper by the European Commission under the DMA.
• Option 3: Not changing the legal framework currently applicable in France and limiting the scope of action of the FCA to the enforcement of provisions on anti-competitive practices after the implementation of the merger.

The FCA has announced that the stakeholders who responded to the public consultation firmly rejected Option 2 and preferred Option 1, which was, however, also criticised for the uncertainty it would create for businesses. The FCA is currently working on a proposal to the French government.

In parallel, the FCA has examined, for the first time, below-threshold transactions under Article 101 TFEU (and the corresponding Article of the French commercial code) on anti-competitive agreements in the meat-cutting sector. However, the FCA concluded that these mergers did not have an anti-competitive object or effect.

Belgium

In its 2025 Priorities Papers, the BCA explicitly stated that it would focus on merger control. In particular, the BCA has announced that it will "evaluate whether it is expedient to introduce a 'call-in' competence […] to allow the BCA to examine the competitive impact of a merger that fails to reach the European and Belgian notification thresholds". According to the BCA, this possibility results from the detrimental impact that killer acquisitions can have on Belgian competitiveness. This consideration has been confirmed by the President of the BCA who further declared, in a LinkedIn post, that Belgium needs a mechanism that allows the BCA to examine below-threshold transactions in order to prevent "roll-up acquisitions" and "killer acquisitions".

There are two reasons for adopting such a mechanism. First, Belgian quantitative thresholds are high compared to other member states (i.e. at least two parties to the acquisition must have a turnover of at least €40 million in Belgium and their combined turnover in Belgium must be at least €100 million). This implies that some transactions which may harm competition do not trigger the notification obligation to the BCA. Second, the BCA currently relies on the ECJ's Towercast ruling (see above) to examine below-threshold transactions. Indeed, as an illustration, the BCA opened two investigations into the Proximus/EDPnet (2023) and Dossche Mills/Ceres (2025) mergers by applying this case law. Nonetheless, according to the President of the BCA, this mechanism would not be as effective as a pre-transaction review process.

It is envisaged that the process of introducing these changes to the Belgian call-in regulatory landscape is likely to take at least one year. Although the President of the BCA has announced his recommendation to hold a public consultation on possible proposals, this has not been officially confirmed.

Spotlight on the UK

Given the voluntary nature of the UK regime, such that parties are not obliged to notify a transaction meeting relevant turnover thresholds, dealmakers must make their own assessment as to whether the CMA might call in their deal for review. If it is believed that a deal may attract scrutiny, proactive engagement with the regulator would be worthwhile, (potentially) via an informal briefing paper in the first instance, together with appropriate conditionality and protections built into deal documentation. This generally involves the merging parties conducting the same sort of initial substantive competition analyses (e.g. reviewing overlaps between the parties' operations) as may now be needed to assess the below-threshold call-in risk by NCAs – see above.

These initial risk assessments have been further complicated by a recent expansion of the CMA's jurisdiction (building on already flexibly applied thresholds) balanced against a changing policy environment in which the CMA is being encouraged by government to be more targeted and proportionate in its interventions.

In January 2025, the Digital Markets, Competition & Consumers Act 2024 (DMCCA) established a new "hybrid" jurisdictional test, designed to address killer acquisitions. The new test, based partly on "share of supply" and partly on turnover, enables the CMA to investigate mergers which do not meet turnover thresholds, but which may nonetheless raise competition concerns in dynamic markets.

Theoretically at least, the new threshold significantly increases the number of transactions which may be reviewed by the CMA, including in circumstances where the target has only limited operational links to the UK (e.g. obtaining local licences or local IP registrations in anticipation of servicing UK customers). The new hybrid test does not require an increment to the parties' share of supply – meaning that the CMA can take jurisdiction over the acquisition of startups and/or deals between firms at different levels of the supply chain and/or in neighbouring markets.

It was anticipated that the new hybrid test could reinforce the CMA's "robust" approach to merger control post-Brexit, which played out in the recent scrutiny of a number of AI partnerships which did not meet relevant thresholds elsewhere. Indeed, the CMA's wide margin of discretion when it comes to applying the share of supply test was confirmed by the Competition Appeal Tribunal following an appeal of the CMA's high-profile decision to block Sabre/Farelogix, despite Farelogix being a US company with no UK turnover.

However, despite the CMA now having a significantly broader remit in terms of merger control, its current pro-growth agenda (established in response to the 2025 Strategic Steer from government) and introduction of the "4Ps" programme for change are expected to result in more "proportionate" and "predictable" decision-making, with a renewed focus on UK consumers and businesses. In particular, as noted in the first alert in the Merger Control Summer Series, the CMA has recently proposed a "wait and see" policy for multi-jurisdictional mergers, whereby it may decide not to open an investigation into a deal already being reviewed by another authority, if the transaction "involves exclusively markets that are wider than the UK" and the proposed remedies are capable of addressing UK competition concerns.

Further, as part of its commitment to the 4Ps, the CMA is currently consulting on an update to its merger guidance on jurisdiction and procedure (see Draft Revised Guidance) in order to improve the predictability of the UK merger control regime by more clearly delineating its jurisdictional remit as it relates to the "share of supply" test (as well as the test for "material influence"). In parallel, the UK government announced in March 2025 that it will be putting forward proposals to reform merger control law to provide "more certainty on where mergers will be subject to investigation in the UK".

For now, dealmakers and their advisers will need to conduct nuanced risk assessments, which take account of these policy and legislative changes, keeping in mind the CMA's latest decisional practice. While it is likely that the CMA will exercise its discretion to "step back" from cross-border deals without a clear impact on UK businesses and consumers, there is no guarantee that this will be the case. In practice, there may also be a risk of future call-in if it emerges that the CMA does not agree with the parties' assessment that the transaction has no UK-specific impact, or if remedies agreed in other jurisdictions do not fully address the competition concerns identified in the UK. In that case, the CMA's wide margin of discretion to call in deals with a seemingly negligible presence in the UK, or between parties which do not compete directly with each other, has only been strengthened.

See also the first alert in the Dentons Merger Control Summer Series, which examined the ways in which regulators in the European Union (EU) and United Kingdom (UK) are responding to the call for competitiveness and growth, while ensuring that future competition is protected.