On 9 September 2026, the General Court of the European Union upheld the prohibition of Booking’s acquisition of eTraveli (see judgment here).
The transaction would have combined two companies primarily active on distinct but related markets:
- online travel agency (OTA) services for hotels, where Booking held a dominant position; and
- OTA services for flights, eTraveli’s core business.
The judgment comes at a time when the European Commission is finalizing its revised merger guidelines. Although the draft published in April 2026 is still under discussion, it reflects an approach broadly consistent with that adopted by the General Court, particularly regarding:
- the strengthening of a dominant position through the acquisition of complementary activities;
- network effects; and
- the assessment of efficiencies.
An Acquisition on an Adjacent Market Can Strengthen a Dominant Position
Although eTraveli was primarily active in the market for flight OTA services, which was distinct from the hotel OTA market in which Booking held a dominant position, the competition concerns identified by the Commission and upheld by the General Court primarily related to the strengthening of that dominant position. The analysis was therefore based on the complementarity between flight and accommodation booking services.
Flight and accommodation booking services are indeed closely complementary within a traveller’s journey. Combining these services enables a platform, in particular, to obtain information about its customers’ destinations and travel dates, offer them different services relating to the same trip and thereby facilitate cross-selling between flights and accommodation.
The acquisition of eTraveli was therefore liable to increase the number of travellers using Booking’s services and the opportunities to offer them its accommodation booking services as well. Through the resulting increase in traffic and cross-selling, the transaction could strengthen Booking’s position in the hotel OTA market.
In this respect, the General Court upheld the Commission’s analysis based on a reverse leveraging effect: eTraveli’s activities in the flight OTA market, in which Booking did not hold a dominant position, could be leveraged to strengthen Booking’s dominant position in the complementary hotel OTA market, in particular by generating more accommodation bookings on its platform.
This approach is also reflected in the Commission’s draft revised Merger Guidelines (the final version of which is expected by the end of 2026), which specifically address the entrenchment of a dominant position, network effects and ecosystems. In this context, the draft Guidelines notably highlight the role that the acquisition of complementary assets, capabilities or services may play in strengthening an existing dominant position.ole that certain complementary assets or services may play in reinforcing an existing dominant position.
Even a Limited, Prospective and Indirect Increase in Market Share May Jeopardize the Transaction
In this case, Booking’s market shares in the hotel OTA market were already very high, at around 60–70% depending on the segments considered in the Commission’s decision. As eTraveli was primarily active in the separate flight OTA market, however, the transaction did not result in a conventional addition of the acquirer’s and target’s market shares in the hotel OTA market.
The Commission had instead sought to quantify the increase in Booking’s market share in the hotel OTA market that could result from the transaction. The acquisition of eTraveli was expected to give Booking access to more travellers at the flight-booking stage and enable it to convert some of them into customers of its hotel booking services. The increment under consideration therefore consisted of an expected increase in Booking’s share of the hotel OTA market resulting from the acquisition of a business active in an adjacent market.
The General Court identified several errors in the Commission’s quantitative assessment and found that it could not be ruled out that the increase might be limited to only a few tenths of a percentage point. Certain other alleged effects, including those relating to hotels’ behaviour and commission rates, had likewise not been established.
Nevertheless, the General Court upheld the Commission’s overall assessment, as the transaction was still capable of strengthening Booking’s dominant position in light of:
- the structure of the market; and
- the importance of the acquired activity (flight OTA services) for the development of the hotel OTA market.
The market structure was characterized by:
- strong network effects;
- a significant gap between Booking and its main competitors;
- high barriers to entry and expansion; and
- a dominant position that was already difficult to challenge.
In such circumstances, even a limited increase could reinforce existing network effects and make it more difficult for competitors to expand their customer base.
The acquired activity on the adjacent market constituted an important growth channel for the already dominated primary market:
- flights represented one of the few hotel customer acquisition channels that Booking did not yet control;
- the transaction could have facilitated the development of a more integrated travel offering; and
- it was capable of affecting certain OTAs that continued to play a role in the competitive dynamics of the hotel market.
In these circumstances, the Significant Impediment to Effective Competition (SIEC) could stem not only from a reduction in competitive pressure following the transaction, but also from the consolidation and perpetuation of an already low level of competition.
This assessment nevertheless remains closely tied to the circumstances of the case. The General Court did not infer harm merely from the preservation of the status quo. Rather, it took into account the expected strengthening of network effects, the strategic role of flight services in customer acquisition, and the additional obstacles that the transaction could create for competitors seeking to expand in the hotel OTA market.
This approach is consistent with the ongoing revision of the EU Merger Guidelines, which:
- places greater emphasis on the dynamic effects of mergers (a development also reflected in the Oxera report prepared for the European Commission and published on 24 August 2026);
- stresses that transactions should be assessed on the basis of all relevant circumstances, including market shares, network effects, barriers to competition and the prospects for entry and expansion by rivals; and
- expressly recognises the entrenchment of a dominant position as a standalone theory of harm.
Efficiencies Subject to Close Scrutiny
The judgment also provides useful guidance on the circumstances in which efficiencies may be taken into account.
Verifiable, Merger-Specific Efficiencies That Benefit Consumers
The applicable framework remains that established by existing case law and reflected in the draft revised guidelines. Efficiencies must be:
- sufficiently verifiable;
- merger-specific;
- likely to be passed on to consumers; and
- balanced against the transaction’s negative effects.
In addition, particular scrutiny is required where the efficiencies and the adverse effects concern different markets or different groups of consumers.
This issue, which is also addressed in the draft revised guidelines, played a significant role in the Booking/eTraveli case:
- the competitive concerns identified related to hotel OTA services;
- whereas part of the claimed efficiencies would have benefited users of flight booking services.
In this case, the General Court did not exclude the possibility that efficiencies achieved in one market could offset harm identified in another. However:
- such an offset requires, among other things, that the consumers benefiting from the efficiencies and those bearing the adverse effects are substantially the same; and
- the mere existence of some overlap between users of flight-booking and accommodation-booking services was not considered sufficient.
Rejection of Insufficiently Substantiated Efficiency Claims
The efficiencies examined on their merits by the General Court primarily concerned flight booking services.
Booking argued in particular that the transaction would allow:
- lower prices through the elimination of double marginalization; and
- competitive responses by other OTAs that would further increase consumer benefits.
The General Court found that the alleged errors in the Commission’s decision were not capable of undermining its assessment of these efficiencies. In particular, it noted that:
- the effective pass-through of cost savings to consumers had not been demonstrated;
- the alleged price reduction appeared too limited to significantly influence consumer behavior; and
- the anticipated responses of competitors were based on assumptions that were insufficiently substantiated and difficult to verify.
The judgment therefore illustrates the demanding evidentiary standard that continues to apply to efficiency claims.
Rejection of Efficiency Claims Raised Too Late in the Procedure
Part of the efficiencies invoked by Booking were not examined on the merits because they had not been presented sufficiently early in the administrative proceedings.
In particular, the General Court noted that the argument relating to a “one-stop shop” bringing together multiple travel services had not been clearly advanced as an efficiency claim during the administrative procedure. It also relied, at least in part, on expert evidence produced after the Commission’s decision.
The case also highlights the importance of identifying and documenting efficiencies from the outset of the Commission’s administrative review process.
Key Takeaways
- Confirmation of ecosystem theories: The acquisition of a company active in an adjacent market may strengthen the acquirer’s dominant position in its core market, particularly where it enables the acquirer to gain access to new customers and steer them toward its own services. While especially relevant in digital markets, this approach is not new and also applies to any interconnected markets.
- Toward an increasingly forward-looking assessment: Even in the absence of a horizontal overlap between the parties in the same market, transactions may raise concerns where the complementarity of activities in adjacent or related markets is likely to consolidate an existing dominant position. A prospective and indirect increase, even a limited one, in the acquirer’s market share on the dominated market resulting from the acquisition of a complementary business may be sufficient to jeopardize the transaction. This is particularly true in markets characterised by strong network effects and significant barriers to expansion.
- Higher evidentiary standards for efficiency claims: Efficiency gains must be prepared and substantiated well in advance. Late submission, insufficient quantification, or the absence of a clear link to the affected consumers may significantly reduce their evidentiary value and limit the extent to which they are taken into account.
Published on 18.09.2026.




