General Court Upholds Commission Prohibition of Booking's Acquisition of Etraveli (case T-1139/23), What It Means for EU Merger Control

Executive summary: the judgment and why it matters

The General Court upheld the Commission’s prohibition of Booking’s acquisition of Etraveli Group, dismissing the action brought against the European Commission’s decision to block the transaction. In its judgment in Case T-1139/23, the General Court confirmed that the Commission was entitled to prohibit Booking Holdings’ proposed purchase of the flight-search and online travel intermediary Etraveli. The ruling matters because it is one of the most significant endorsements yet of an ecosystem-based theory of harm in European merger control, and it signals to notifying parties that the Commission’s scrutiny of platform integration and cross-service leverage now carries robust judicial backing.

For competition counsel advising on digital, marketplace and multi-sided transactions, the decision reshapes how theories of harm, market definition and remedies must be anticipated and addressed well before formal notification.

Quick facts and case timeline (T-1139/23)

The dispute concerns Booking Holdings’ proposed acquisition of Etraveli Group, a transaction that would have combined a leading online accommodation platform with a flight-search and ticketing intermediary. The Commission examined the deal under the EU Merger Regulation, raised concerns that it would strengthen Booking’s travel ecosystem to the detriment of rivals, and ultimately adopted a prohibition decision in September 2023. Booking challenged that decision before the General Court, which dismissed the action.

• Notification and investigation. The concentration was notified to and investigated by the Commission, which opened an in-depth (Phase II) review of the competitive effects across accommodation and flight-related services.
• Prohibition decision. The Commission prohibited the acquisition, concluding it would significantly impede effective competition.
• Appeal. Booking brought an action for annulment before the General Court, registered as Case T-1139/23.
• Judgment. The General Court dismissed the action and upheld the Commission’s prohibition of the deal in its entirety.

Key documents to read

Practitioners should consult the primary sources directly. The full text of the General Court judgment is available on CURIA, the case-law database of the Court of Justice of the European Union. The Commission’s prohibition decision, together with the associated procedural documents, can be located through the European Commission’s mergers case register. The substantive legal framework is set out in Council Regulation (EC) No 139/2004, the EU Merger Regulation.

What the Commission alleged: ecosystem theory and specific concerns

At the heart of the prohibition was the Commission’s concern that the transaction would reinforce Booking’s already substantial position in online travel by embedding a complementary service, flight search and ticketing, into a broader travel ecosystem. Rather than resting on a simple horizontal overlap between two directly competing products, the Commission’s theory of harm focused on how the merged entity could leverage its platform reach, customer base and data to disadvantage rival online travel intermediaries and to foreclose competing complementary services.

The essence of the concern was dynamic and cumulative. Booking’s accommodation platform functions as a powerful acquisition channel for customers. By integrating flights, the Commission reasoned, Booking could increase customer touchpoints, reinforce user lock-in, and expand the reach of its ecosystem in ways that competing flight intermediaries and travel agencies could not readily match. The result would be a self-reinforcing advantage: more services attract more customers, more customers generate more data, and more data improves the platform’s ability to convert and retain users across the travel journey.

Market definition approach used by the Commission

The Commission’s market analysis moved beyond a narrow product-by-product exercise. While it identified relevant markets for online travel intermediation and flight-related services, the substantive assessment gave weight to the interdependencies between these services and to the role of the accommodation platform as an entry point into the wider travel ecosystem. This approach draws on established principles in the Commission’s Notice on the definition of the relevant market, but applies them in a setting where cross-market linkages and platform dynamics, rather than in-market substitution alone, drive the competitive concern.

Evidence and empirical indicators cited

The Commission grounded its concerns in evidence about customer behaviour, the strength of Booking’s platform as a distribution channel, the value of accumulated data, and the difficulty rivals would face replicating an equivalent ecosystem. The concern was not merely that the merged firm would be larger, but that it would acquire an enhanced ability and incentive to leverage its position across complementary services in a manner that could degrade the competitive prospects of rivals over time. This evidentiary emphasis on foreclosure and ecosystem reinforcement, rather than on immediate price effects in a single product market, is a notable feature of the case for merger practice.

What the General Court held, legal findings

The General Court’s dismissal of the action confirms that the Commission’s ecosystem-based reasoning was legally sound and adequately supported by the evidence. In upholding the prohibition, the Court addressed the standard of review, the assessment of market definition and substitutability, and the treatment of foreclosure and complementary services. In upholding the Commission’s prohibition on these grounds, the Court gave the ecosystem approach a durable footing in EU jurisprudence.

Standard of review on points of fact and law

Consistent with settled case law, the General Court reviewed the Commission’s decision to verify whether the evidence relied upon was factually accurate, reliable and consistent, whether it contained all the information necessary for the assessment, and whether it was capable of substantiating the conclusions drawn. Where the Commission’s analysis involved complex economic assessments, the Court confined its review to checking that the rules of procedure and the duty to state reasons had been observed, that the facts were accurately stated, and that there was no manifest error of assessment or misuse of powers.

Crucially, the Court found that the Commission had discharged this evidentiary burden in relation to its ecosystem theory of harm, a finding that materially raises the confidence with which the Commission can advance similar theories in future.

Findings on market definition and substitutability

The General Court endorsed the Commission’s approach to defining the relevant markets and to assessing substitutability. Importantly, the Court accepted that a rigorous analysis of the competitive effects need not be confined to a single product market where the transaction’s principal concern arises from the interaction between complementary services and the reinforcement of a platform ecosystem. In doing so, the Court validated a mode of analysis that looks across markets, treating the accommodation platform and the flight-related services as linked components of a broader competitive assessment rather than as isolated silos.

Findings on foreclosure and innovation effects

The Court confirmed that the Commission was entitled to conclude that the merged entity would have the ability and incentive to strengthen Booking’s ecosystem in a way that could foreclose or disadvantage rivals across complementary services. The reasoning recognised that harm to competition in ecosystem settings may be cumulative and forward-looking: the concern is not solely an immediate price increase but the progressive weakening of competitors’ ability to compete on the merits as the dominant platform’s gravitational pull increases. That the Court upheld the Commission’s prohibition on this basis is a clear signal that foreclosure-driven, ecosystem-level theories can survive judicial scrutiny when properly evidenced.

Ecosystem theories of harm: doctrinal implications

The judgment consolidates ecosystem theories of harm within the analytical toolkit of EU merger control under the EU Merger Regulation. An ecosystem theory of harm looks beyond the immediate horizontal overlap between merging parties and asks whether a transaction enables one party to leverage a strong position in one service to entrench or extend market power across complementary or adjacent services. The relevant questions concern the ability to foreclose rivals, the control of critical distribution or access points, the exploitation of data and network effects, and the incentive to degrade interoperability or access for competitors.

How this aligns with or departs from prior cases

The approach builds on the Commission’s long-standing power to assess non-horizontal effects, including conglomerate and leveraging concerns, under the substantive test in the EU Merger Regulation. What distinguishes the ecosystem framing is its emphasis on the cumulative, self-reinforcing dynamics of digital platforms, where customer acquisition, data accumulation and cross-service integration combine to create advantages that are difficult for rivals to replicate. The judgment does not discard traditional unilateral-effects analysis; rather, it confirms that where the competitive dynamics are driven by platform reinforcement across complements, the Commission may and should assess those dynamics directly.

Practical tests to apply to future cases

For counsel assessing a prospective transaction, the practical questions that flow from the doctrine are:

• Ability to foreclose. Does the merged entity control a distribution channel, customer base or data asset that rivals cannot easily replicate?
• Incentive to leverage. Would the merged firm have a commercial rationale to favour its own complementary services or to disadvantage competitors?
• Effect on competition. Would the leveraging weaken rivals’ ability to compete across the ecosystem over time, harming customers through reduced choice, innovation or quality?
• Durability of the advantage. Are the resulting advantages self-reinforcing through data and network effects, making entry or expansion by rivals progressively harder?

Treatment of complementary products and platforms after the judgment

Perhaps the most consequential aspect of the judgment is its treatment of complementary products. Traditionally, merger analysis has concentrated on substitution, whether two products compete closely enough to constrain each other’s pricing. The Booking/Etraveli case demonstrates that complementary relationships, and the platform dynamics that connect them, can themselves generate competition concerns that justify prohibition. The table below summarises how the analytical emphasis shifts once the ecosystem reasoning endorsed in T-1139/23 is applied.

Complementarity versus substitution

The judgment confirms that the absence of a direct substitution relationship between the merging parties’ core products does not neutralise competition concerns. Where the products are complementary and one party operates a strong platform, the combination may create the ability to steer, bundle or prioritise services in ways that disadvantage rivals. Counsel can no longer assume that a lack of horizontal overlap will clear a transaction; the interaction between complements is now firmly within the Commission’s analytical scope.

Evidence thresholds

The General Court’s endorsement of the Commission’s evidence indicates that ecosystem theories, while ambitious, must still be substantiated. The Commission succeeded because it grounded its concerns in concrete evidence about platform reach, customer behaviour, data value and the practical difficulty rivals would face. Notifying parties, in turn, should expect that generalised assertions of pro-competitive integration will not suffice to rebut a well-evidenced foreclosure theory; they will need equally rigorous economic and empirical material of their own.

Practical takeaways for notifying parties: a ten-point checklist

The clearest practical lesson is that transactions involving platforms, marketplaces or complementary digital services now demand ecosystem-aware preparation from the outset. The following checklist translates the judgment into concrete steps for notifying parties.

1. Map the ecosystem early. Identify every service, platform and data asset each party controls, and how they interact, before drafting the notification.
2. Assess complementary relationships. Analyse not only horizontal overlaps but also complementary and adjacent services where leveraging concerns could arise.
3. Gather cross-platform usage data. Assemble evidence on customer journeys, cross-selling, distribution channels and switching behaviour to inform the competitive narrative.
4. Model foreclosure scenarios. Commission economic analysis that tests the ability and incentive to foreclose rivals across complements, rather than focusing solely on price effects.
5. Evaluate data and network effects. Quantify the extent to which combined data assets and network effects could entrench the merged firm’s position over time.
6. Stress-test market definition. Prepare for the Commission to look across markets; develop a defensible position on both narrow product markets and broader ecosystem linkages.
7. Engage in pre-notification dialogue. Use the pre-notification phase to understand the Commission’s concerns and to shape the evidentiary record proactively.
8. Design remedies before you need them. Consider structural and access-based commitments that credibly address ecosystem-level foreclosure, and be realistic about what the Commission will accept.
9. Plan the timeline realistically. Anticipate an in-depth review for ecosystem-sensitive deals and build the additional duration into transaction planning and financing.
10. Prepare a robust efficiencies case. Where integration genuinely benefits customers, document verifiable, merger-specific efficiencies that could not be achieved by other means.

In practical drafting terms, notifying parties should frame their submissions around the ecosystem question directly rather than avoiding it, demonstrating, with evidence, why the combination does not confer an ability or incentive to foreclose, and why rivals retain effective alternatives. Given that the Court upheld the Commission’s ecosystem analysis, silence on ecosystem effects is likely to be read as a gap rather than a strength.

Remedies and enforcement: what options remain and new considerations

The judgment has direct consequences for remedy design. Under the EU Merger Regulation, parties may offer commitments to address competition concerns, and these can be structural (such as divestitures) or behavioural (such as access or interoperability commitments). The Commission has consistently signalled a preference for structural remedies where they can resolve concerns cleanly, because behavioural remedies require ongoing monitoring and can be difficult to enforce over time.

In ecosystem cases, this preference takes on added weight. Where the concern is that a merged firm can progressively leverage its platform to foreclose rivals across complementary services, behavioural commitments, for example, promises of non-discrimination or continued access, must be shown to be genuinely effective against a dynamic, evolving harm. The difficulty is that monitoring compliance in a fast-moving digital ecosystem is demanding, and the incentive to erode access in subtle ways may be strong. Structural remedies that remove the source of the leveraging concern may therefore be more likely to satisfy the Commission where the foreclosure risk is systemic.

Designing remedies for ecosystems

For counsel constructing a remedies package, the key considerations are effectiveness, durability and monitorability. A credible package should target the specific mechanism of harm identified by the Commission, whether that is control of a distribution channel, a data advantage or the ability to bundle complementary services. Access and interoperability commitments should be precise, time-appropriate and supported by robust monitoring and dispute-resolution mechanisms. Comparative material from the OECD on merger remedies underscores the international recognition that behavioural remedies in digital markets carry heightened enforcement risk, reinforcing the case for structural solutions where feasible. The overarching message is that remedies must be designed to neutralise the ecosystem dynamic itself, not merely to soften its symptoms.

Who is affected: scope and likely future cases

While the case arose in online travel, its implications extend well beyond that sector. Any transaction that combines a strong platform or marketplace with complementary services, in areas such as e-commerce, digital advertising, mobility, financial services, media and software, should be assessed through the ecosystem lens. Traditional businesses are not immune either: where a company controls a critical distribution channel or dataset and acquires a complementary provider, similar leveraging concerns can arise. Many observers expect the Commission to draw on this judgment when framing theories of harm in future platform-related mergers, and the likely practical effect will be more frequent and more searching scrutiny of ecosystem integration across a range of sectors.

Conclusion: summary and next steps for counsel

The General Court’s decision upholding the Commission’s prohibition of Booking’s acquisition of Etraveli marks a significant moment for EU merger control. It confirms that ecosystem theories of harm, when properly evidenced, can withstand judicial review, that complementary products and platform dynamics fall squarely within the Commission’s substantive assessment, and that remedies must be designed to neutralise foreclosure at the ecosystem level. For counsel, the immediate steps are clear: audit prospective transactions for ecosystem exposure, assemble rigorous cross-platform and economic evidence early, engage constructively in pre-notification dialogue, and prepare credible, often structural, remedies before concerns crystallise. Deals that ignore these dynamics now face materially heightened prohibition risk.

Sources

1. Council Regulation (EC) No 139/2004 (EU Merger Regulation)
2. European Commission, Mergers (overview and case register)
3. Court of Justice of the European Union, CURIA (case-law database)
4. OECD, Competition and Merger Control resources
5. European Commission, Notice on the definition of the relevant market