Recital 52

In such situations, the gatekeeper should not engage in any form of differentiated or preferential treatment in ranking on the core platform service, and related indexing and crawling, whether through legal, commercial or technical means, in favour of products or services it offers itself or through a business user which it controls. To ensure that this obligation is effective, the conditions that apply to such ranking should also be generally fair and transparent. Ranking should in this context cover all forms of relative prominence, including display, rating, linking or voice results and should also include instances where a core platform service presents or communicates only one result to the end user. To ensure that this obligation is effective and cannot be circumvented, it should also apply to any measure that has an equivalent effect to the differentiated or preferential treatment in ranking. The guidelines adopted pursuant to Article 5 of Regulation (EU) 2019/1150 should also facilitate the implementation and enforcement of this obligation.