Why self-preferencing complaint under the DMA happens

TL;DRA self-preferencing complaint under the Digital Markets Act (DMA) arises when a gatekeeper platform – such as Amazon on its Spanish marketplace – ranks, displays, or treats its own products and services more favorably than those of third-party sellers without objective justification. Under Article 6(5) of the DMA, gatekeepers are prohibited from doing this. For an Amazon ES seller, the practical result can range from suppressed buy-box placement to de facto exclusion from key promotional surfaces, with a formal complaint to the European Commission the primary regulatory lever available.

A Spanish marketplace listing drops in search rank. The buy box shifts to Amazon's own label. Revenue falls sharply within a short window, yet no policy violation notice ever arrives. That is the pattern in many self-preferencing disputes – the mechanism is invisible in Seller Central, the harm is commercial and immediate, and the formal legal basis to challenge it only became operational with the DMA's gatekeeper designation of Amazon. This analysis explains how self-preferencing complaints work, what the procedural path looks like for an Amazon ES seller, and where the real decision points lie.

What self-preferencing under the DMA actually means for Amazon ES sellers

Self-preferencing is the practice of a platform operator favoring its own downstream commercial operations over rival third-party sellers who depend on the same platform to reach customers. The DMA defines Amazon as a gatekeeper – a designation confirmed by the European Commission – meaning Amazon must comply with a set of mandatory behavioral obligations, including the prohibition on self-preferencing in organic ranking and display.

For a seller on Amazon ES, self-preferencing shows up in several recognizable forms. Amazon's own branded products or Amazon Warehouse listings may appear systematically higher in organic results for the same search query. Amazon's private-label goods may win the featured offer (the buy box) at the same price, or even at a slightly higher price, than a third-party seller. Amazon's logistics services – fulfilled-by-Amazon, for instance – may be weighted as a ranking signal in ways that disadvantage sellers using alternative carriers.

The key legal point is what the DMA demands: Amazon must apply transparent, fair, and non-discriminatory conditions to ranking. Where Amazon uses data generated by third-party sellers on its platform to give its own retail arm a competitive advantage, that too can constitute a form of self-preferencing prohibited under the DMA's data-use obligations. In matters we handle, sellers often conflate a standard performance-based ranking drop with potential DMA misconduct – and they are right to examine the distinction carefully, because the remedies available differ substantially.

What distinguishes a DMA self-preferencing complaint from, say, a P2B Regulation ranking complaint is the enforcement route and the potential outcome. The EU marketplace regulation complete guide for sellers sets out the full regulatory architecture; in brief, the DMA creates obligations enforceable by the European Commission with substantial fines, while the P2B Regulation gives individual sellers a more limited but more accessible internal-complaint pathway. A well-advised seller may use both in parallel.

The operator impact is direct and measurable in cash terms. Buy-box suppression on a high-velocity listing translates into lost conversions daily. If the suppression persists across a product category, the inventory cycle is disrupted – stock tied up in Amazon's fulfillment centers generates storage fees without generating sales. In matters we handle for Amazon ES sellers, we regularly see this combination: a revenue shortfall, rising FBA storage costs, and a seller who has not yet connected the commercial harm to the regulatory mechanism that might address it.

How the DMA gatekeeper designation creates a complaint right sellers did not have before

The DMA gatekeeper designation is the legal predicate for a self-preferencing complaint, and it is important to understand exactly what it gives a seller – and what it does not. A gatekeeper is not a passive host; it is a regulated entity subject to affirmative obligations, and those obligations are directly enforceable by the European Commission.

Before the DMA, a seller suspecting self-preferencing had limited formal options. The P2B Regulation required Amazon to disclose its ranking parameters in general terms, but did not give the Commission power to fine Amazon for specific preferencing practices. Competition law – Articles 101 and 102 of the Treaty on the Functioning of the European Union – could theoretically apply, but abuse-of-dominance cases are slow, resource-intensive, and almost never pursued on the initiative of a single affected seller.

The DMA changes the calculus. The European Commission opened its DMA non-compliance investigation into Amazon's self-preferencing practices, and Amazon received formal preliminary findings. This matters for individual sellers because it creates a factual and legal context in which a complaint has credibility and a path. The Commission can act on complaints from third parties – including affected sellers – as part of an investigation; it is not limited to opening proceedings on its own initiative.

A DMA gatekeeper designation is also a Very Large Online Platform (VLOP) designation under the Digital Services Act (DSA). The DSA adds a second layer of systemic transparency obligations, including meaningful access to data about how recommendation and ranking systems operate. A seller who wants to document a self-preferencing pattern will often need both the DMA's substantive prohibition and the DSA's transparency mechanisms to build a credible factual record.

What this means practically: the DMA does not give a seller a private right of action in the same way that, say, a trademark infringement claim gives an IP holder the ability to sue in national court. The primary enforcement authority is the Commission. However, sellers can and do file complaints that inform and accelerate Commission action, and – critically – several EU member states have opened parallel national proceedings under their own competition laws, some of which do carry private remedies. For Amazon ES specifically, the Spanish competition authority (the CNMC) is an active enforcer in the digital platform space.

What the realistic procedural path looks like

A self-preferencing complaint under the DMA follows a distinct procedural path, and understanding it is the first step to deciding whether to pursue one. The path has three phases: internal escalation, Commission complaint, and parallel national remedies – and the sequence matters.

The first phase is Amazon's internal complaint-handling system. Both the P2B Regulation and the DSA require Amazon to operate an accessible, timely, and non-discriminatory internal complaint mechanism for business users. That means before a seller files a formal DMA complaint with the Commission, the internal system should be used – both because it may produce a faster practical result and because exhausting it creates a documented record. In matters we work on, we regularly see sellers bypass this step, which weakens their later regulatory complaint by removing what would otherwise be a clean paper trail of denied or ignored escalation.

The second phase is the formal complaint to the European Commission. A DMA complaint is submitted through the Commission's designated channel, setting out the factual basis, the specific DMA obligation allegedly breached, and the commercial harm. The complaint does not need to prove the breach to a final standard – it needs to be sufficiently detailed and credible to warrant the Commission's attention. The Commission has discretion over whether to act on any individual complaint; the strongest complaints are those tied to a pattern, supported by data, and filed in a period when the Commission already has an open investigation or preliminary finding on the relevant practice.

DMA investigations can take a substantial period – often more than a year from opening to a formal finding – which means a seller who waits for a Commission decision before taking any other action may face a prolonged revenue impact. That is why the third phase – parallel national remedies – matters so much in practice.

In Spain, the CNMC can receive complaints under national competition law (the Ley de Defensa de la Competencia), and for a seller with a sufficiently significant market presence, a national complaint may move faster than the Commission path and may yield an interim remedy. The P2B Regulation's internal mediation mechanisms provide another lower-cost option, particularly for ranking complaints that can be framed in P2B terms. German marketplace suspension procedure shows how a parallel national enforcement approach can run alongside EU-level action – the same multi-track logic applies in Spain.

A micro-case from our practice: a home-goods seller on Amazon ES (winter 2025) came to us after organic rankings for their core SKUs dropped steadily over several months, coinciding with the expansion of Amazon's own private-label range in the same category. We mapped the timeline, gathered the seller's ranking data and sales records, and documented the comparative placement of Amazon's own product against the third-party listing at equivalent price points. We filed through Amazon's internal complaint channel first, received a non-substantive response, and then prepared a factual submission for regulatory consideration. The seller also opened a parallel conversation with legal counsel experienced in Spanish competition matters. The DMA complaint was filed and the internal complaint record served as a primary exhibit.

The seller's real decision points and trade-offs

The decision to file a DMA self-preferencing complaint is not simple. It involves genuine trade-offs, and the right choice depends on the specific situation of the seller, their account relationship with Amazon, the strength of their data, and their commercial priorities.

The first trade-off is time versus impact. A Commission DMA complaint is powerful but slow. If a seller's primary need is to stop a buy-box suppression that is currently damaging daily revenue, a DMA complaint alone will not solve that in the short term. The internal complaint mechanism, combined with a well-documented escalation through Seller Central's Account Health and performance channels, may produce a faster operational response – even if it lacks the formal force of regulatory action. The DMA complaint then serves a longer-term and broader purpose: it contributes to the Commission's enforcement record and, if the Commission acts, the result benefits not just one seller but the category as a whole.

The second trade-off is visibility versus leverage. Filing a formal complaint with the Commission is not confidential in the same way that an internal legal matter is. Amazon may learn that a specific seller has filed or assisted in a regulatory complaint. For most sellers this does not alter Amazon's behavior at the account level – Amazon is a large platform and individual seller complaints are processed at a distance from account management. But it is a real consideration, and sellers should think through the commercial relationship before acting.

The third trade-off is cost and resource. Building a credible DMA complaint requires data – ranking data, price parity data, buy-box history, sales records. Sellers who have not been tracking these metrics systematically will need to reconstruct what they can from available exports, third-party tools, and their own records. The effort is significant. An attorney-led engagement is worth considering for sellers whose exposure justifies the investment, both because the complaint will be better constructed and because an attorney can assess whether the national competition law route offers a faster parallel path.

The myth that EU sellers have no leverage once a platform acts against them is exactly that – a myth. The DMA, the DSA, the P2B Regulation, and national competition law together give EU sellers a layered set of tools that simply did not exist before 2020. Whether the tools are worth using depends on the scale of the harm, the quality of the evidence, and the patience of the seller – but the tools exist and, in our practice, we regularly use them on behalf of sellers whose situations warranted it.

If the notice or commercial impact cites a ranking issue tied to a specific product category and the timing correlates with expansion of Amazon's own offerings, the DMA route is worth analyzing. If instead the issue is a compliance-based suspension or a listing takedown tied to policy enforcement, the correct path runs through the P2B internal complaint mechanism first and potentially the DSA's statement-of-reasons obligation – which gives sellers the right to an explanation of why a specific decision was made. That distinction – DMA versus DSA/P2B – is the first thing we assess when a seller contacts us about an EU marketplace dispute.

Documenting a self-preferencing pattern: what you need before filing

A well-documented complaint is substantially more likely to be taken seriously by the European Commission than a bare assertion. Documenting a self-preferencing pattern requires a methodical approach, and sellers who start too late – after the ranking data has cycled out of available exports – lose evidence they cannot recover.

The core evidentiary components are ranking history, buy-box history, price parity data, and Amazon's own listing placement for the competing product. Ranking history can be extracted from third-party tools and from Seller Central's own search analytics, though the granularity available varies. Buy-box history is partially reconstructable from the seller's own sales data – a sudden drop in buy-box win rate, correlated with a new Amazon-branded listing in the same category, is a significant data point. Price parity data matters because the DMA prohibition on self-preferencing is most clearly violated when Amazon's own product wins placement despite being priced at or above the third-party listing.

Beyond the quantitative record, qualitative documentation matters. Screenshots of Amazon's own listings appearing prominently in organic search results for exact queries where a third-party product previously ranked, annotated with dates, are admissible as supporting evidence. A written chronology of the events – when the ranking dropped, when Amazon's own product appeared, when internal escalation was attempted and what response was received – provides the narrative frame that makes the data legible to a regulator.

Sellers should also preserve their communications with Amazon. Any message through Seller Central, any Account Health notice, any response to an escalation is part of the record. The internal complaint filed under the P2B mechanism should be preserved in its entirety, including Amazon's response, even if the response is a form letter. That record is evidence that the internal path was tried and failed to resolve the issue – which is exactly the kind of documented escalation that strengthens a Commission complaint.

A second micro-case: an electronics accessories seller on Amazon DE (spring 2026) identified a pattern in which their core ASIN consistently lost the buy box to an Amazon-branded product at nearly identical prices, despite a longer sales history and significantly more reviews. We worked with the seller to build the evidentiary file over several weeks, pulling ranking and buy-box data, documenting the comparative listing placement, and correlating the timing with a known expansion of Amazon's private-label electronics range. The internal complaint yielded no substantive result; the documentation was then used in a regulatory submission. The case illustrates that the documentation phase, done properly, creates value beyond the complaint itself – it clarifies whether the pattern is genuinely attributable to self-preferencing or to other ranking variables. In this matter, that distinction was important. See also the analysis of UK marketplace suspension after Brexit for the contrast in regulatory tools available outside the EU.

How fees work and what engagement with Tutamen looks like

EU marketplace regulation work is typically structured around a fixed scoping fee to start. That initial engagement covers a review of the seller's situation, an assessment of which regulatory instrument – DMA complaint, DSA statement-of-reasons request, P2B internal complaint, or national competition law referral – is the right tool, and a clear statement of what we can do and what the realistic path looks like. The scoping fee is quoted up front, before any commitment.

For matters that move to a full regulatory complaint, the fee model reflects the complexity and the scope of the work: preparation of the evidentiary record, drafting and filing the internal escalation, preparation of the Commission complaint or national authority submission, and ongoing coordination as the matter develops. All fees are attorney-led and fixed or capped, quoted up front after the short review. We do not take EU regulatory matters on a contingency basis, given the nature of the enforcement pathway.

What sellers most often tell us they value at the outset is not the specific fee amount – it is the clarity about what the realistic path is. A suspension under EU rules can look final and the appeal path can seem opaque. Our role in the first engagement is to map it, clearly and honestly, so the seller can make an informed commercial decision about whether to proceed.

Related areas

• EU Marketplace Regulation – complete guide – the full regulatory architecture for Amazon and other EU platforms
• German Marketplace Suspension – step-by-step handling of a suspension on Amazon DE
• UK Marketplace Suspension After Brexit – the post-Brexit regulatory divergence and what it means for sellers

If you are an Amazon ES seller whose rankings, buy-box placement, or revenue have been affected by what may be a self-preferencing pattern, the window to gather and preserve evidence is now, not after a Commission proceeding is underway. Email info@tutamenlaw.com for a scoping review – we will assess your situation, identify the applicable instruments, and give you a fixed-fee quote for the next step.

Frequently asked questions

How long does resolving self-preferencing complaint under the DMA usually take on Amazon ES?

There is no fixed timeline, and sellers should plan for a range of outcomes at different speeds. The internal complaint mechanism under the P2B Regulation and DSA typically generates a response within several weeks, though that response may be non-substantive. A formal DMA complaint to the European Commission becomes part of an investigation that can run for an extended period – well over a year in complex cases. Parallel national competition proceedings in Spain, before the CNMC, may move somewhat faster, particularly where interim measures are sought. The practical advice is to pursue the internal mechanism first and use the Commission route for the longer-term systemic remedy rather than an immediate fix.

What are the main risks if I handle self-preferencing complaint under the DMA alone?

The main risks are evidentiary and strategic. A DMA complaint that lacks a coherent factual record – documented ranking data, buy-box history, comparative placement evidence – is unlikely to advance. Sellers who bypass the internal complaint mechanism lose a documented escalation trail that strengthens the Commission submission. Sellers who frame the complaint imprecisely – conflating a P2B ranking complaint with a DMA self-preferencing argument – may find the wrong instrument applied to the right problem. There is also the sequencing risk: acting too quickly, before the evidence is assembled, can mean the strongest data points have not been captured. Attorney-led preparation reduces all of these risks materially.

Do I need a lawyer for self-preferencing complaint under the DMA?

You are not required to use a lawyer to file with the European Commission or to submit an internal complaint. But the value of legal involvement is in the assessment before filing and the evidence architecture, not in the act of submission itself. An experienced marketplace-regulation lawyer can identify whether the facts actually support a DMA self-preferencing argument, as opposed to a P2B ranking complaint or a DSA statement-of-reasons request – which are different instruments with different procedural paths and different realistic outcomes. For matters with significant commercial exposure, attorney-led engagement typically produces a more credible complaint and a more realistic strategy for the seller.

About Tutamen

Tutamen is an independent law firm for online marketplace sellers. We represent Amazon, Walmart, Etsy and eBay sellers in account deactivations, frozen-funds recovery, intellectual-property disputes, arbitration and Notices of Dispute, and US federal Schedule A defense, plus EU marketplace regulation. Our work is attorney-led and confidential, with fees quoted up front. We act for founders, brand owners and in-house teams who need a specialist for a marketplace dispute. Our EU regulatory practice covers DSA, DMA, P2B, GPSR, and EPR compliance and enforcement matters across EU and UK marketplaces. To discuss your situation, email info@tutamenlaw.com.

Disclaimer: This article is general information, not legal advice, and does not create an attorney-client relationship. Marketplace policies and the law change, and every account and case is different. For advice on your situation, contact Tutamen at info@tutamenlaw.com.

By Dmitri Aronov – Partner, EU Marketplace Regulation | Tutamen | February 17, 2027