Two Landmark Decisions on Sub-Threshold Merger Control

German Cartel Office’s Rethmann Group Decision: Ex-Ante Notification Obligation for Below-Threshold Transactions

The German Cartel Office (Bundeskartellamt), in November 2025, ruled on the Rethmann Group, which includes the waste management company Remondis[1] , requiring the group to notify the Cartel Office three years in advance of any future mergers and acquisitions it intends to carry out in the waste management sector, particularly in the areas of non-hazardous municipal waste collection and glass waste processing. This decision is of particular importance as it represents the first concrete application of Section 32f(2) of the German Competition Act (Gesetz gegen Wettbewerbsbeschränkungen – GWB).

GWB Section 32f(2), which came into force in 2021 and was extended in scope at the end of 2023, constitutes an exceptional provision in the merger control regime. This provision allows transactions below the threshold to be subject to review by the German Cartel Office under certain conditions. The fundamental aim of the regulation is to preventively control transactions that fall outside the classic threshold system but have the potential to structurally restrict competition.

Under this provision, following a completed sector inquiry, the German Cartel Office may impose a notification obligation on a particular undertaking if there are objective and verifiable indications that future mergers and acquisitions by that undertaking could significantly impede competition. This notification obligation is valid for three years and is subject to the condition that the transaction is not insignificant and that the target undertaking achieves a turnover of at least EUR 100,000 in the relevant activities.

The Rethmann decision is based on the findings of the German Cartel Office's comprehensive investigation into the waste management sector, completed at the end of 2023[2] . The investigation found that the Rethmann Group is the market leader in the collection of non-hazardous municipal waste and in the glass waste processing market, both nationally and in various federal states, and that it has a strong financial structure and a clear advantage over its competitors. The Group companies' exceptionally strong access to the relevant regional markets, their widespread geographical presence, and the increased barriers to entry in the market as a result of previous acquisitions were particularly highlighted. Furthermore, it was determined that the number of bidders in waste collection tenders launched by municipalities and in tenders related to the packaging recycling system (duales System) has steadily decreased. In this context, the German Cartel Office concluded that even the acquisition of small-scale competitors operating only at the regional level could further weaken the competitive structure in the long term.

The Rethmann decision is an important milestone in the German merger and acquisition control regime. The decision demonstrates that the Cartel Office can conduct ex-ante reviews of transactions that fall below the threshold but pose a structural competition risk, going beyond its traditional supervisory approach. In this respect, the decision sets a precedent, particularly for concentrated sectors with high barriers to entry.

French Competition Authority's Doctolib Decision: Ex-Post Intervention in Sub-Threshold Mergers

In its November 2025 Doctolib decision, the French Competition Authority (Autorité de la concurrence)[3] assessed and sanctioned an acquisition that fell below national notification thresholds and was therefore not subject to ex-ante review, for the first time on the grounds of abuse of a dominant position.

Doctolib is a digital health platform offering online medical appointment booking and remote medical consultation services in France. Doctolib's acquisition of MonDocteur, one of its main competitors, in 2018 was not subject to any review, as it fell below both national and EU merger control thresholds. However, the French Competition Authority's investigation into Doctolib in 2021 has brought this transaction back into the spotlight.

The investigation concluded that Doctolib had been dominant in the online medical appointment booking market since at least 2017, with its market share consistently exceeding 50% between 2017 and 2022 and exceeding 90% in some years. Similarly, it was determined that Doctolib also held a dominant position in the remote medical consultation solutions market. It was established that following the acquisition, Doctolib permanently increased its market share, raised its prices several times, and did not experience any significant customer loss despite these increases.

Under the French merger and acquisition control regime (Code de commerce m. L.430-2), only transactions exceeding certain turnover thresholds are subject to notification. However, the Doctolib decision is noteworthy in that it clearly establishes that below-threshold transactions can be reviewed ex post.

The legal basis for the decision is the European Court of Justice's Towercast ruling (C-449/21) dated 16 March 2023. In the Towercast judgment, the Court of Justice clearly stated that there is no legal obstacle preventing a transaction not subject to notification under EU or national merger control from being assessed under Article 102 TFEU as an abuse of a dominant position. The Court also stated that Merger Regulation No 139/2004 cannot prevent national competition authorities and courts from examining mergers without an EU dimension on the basis of the direct effect of Article 102 TFEU.

In light of all these assessments, the French Competition Authority imposed a fine of €4.6 million on Doctolib for its behavior aimed at closing the market and excluding competitors , and found that Doctolib had acquired its competitor MonDocteur with the aim of eliminating it and closing the market. Although this acquisition fell below the notification threshold, the Authority imposed a limited and symbolic fine of €50,000, taking into account that the infringement occurred prior to the Towercast decision. Finally, Doctolib was required to publish a summary of the decision in the Le Quotidien du Médecin newspaper and on its website.

The Doctolib decision clearly demonstrates that merger control thresholds can no longer be considered an absolute "safe harbor." It has become clear that even small-scale, below-threshold acquisitions may pose a risk of competition law infringement, particularly for dominant undertakings.

Conclusion

The scrutiny of acquisitions that fall below the threshold but are of a strategic nature has become one of the priority issues for competition authorities. The approach taken by the German and French authorities in their decisions at the end of 2025, although exceptional, demonstrates that sub-threshold mergers and acquisitions cannot automatically be considered "risk-free." German competition law regulations, through GWB § 32f(2), provide for a targeted and ex-ante notification obligation for certain undertakings, while French regulations, in line with the Towercast case law, prefer an ex-post and general review process. Although the ex-ante review envisaged under GWB § 32f(2) offers greater predictability for undertakings, the ex-post approach of the French Competition Authority has created a significant legal certainty issue, particularly for undertakings in a dominant position. Both approaches demonstrate that competition authorities in Europe are closely focusing on below-threshold mergers and acquisitions and diversifying their review tools. In particular, it is evident that not exceeding turnover thresholds alone does not provide sufficient assurance for acquisitions carried out by undertakings in a dominant position.