visited web page and by its geographical location. Some respondents specified that the differentiation between search and non-search ads merely reflects the "triggering mechanism" that determines which ad to place in the inventory space and the different attitude of the viewer (more focused when using a search query), but that this does not necessarily imply the identification of a separate market.
Other respondents to the Commission's market investigation also pointed out that all these different types of ads could be considered as substitutable despite the different appearance and targeting properties (reflected in different pricing mechanisms). These respondents submit that the different forms of online ads can be perceived as substitutes as they would compete for the same ad space inventory.
The market investigation also showed that, from a technical point of view, the differences between the different types of ads seem to be diminishing. With respect to the targeting dimension, whilst search ads have been traditionally viewed as more effective than non-search advertisements (given that search queries are clear regarding the users' intentions or interests), the ability of non- search ads to target relevant consumers is improving. Furthermore, whereas non-search and in particular display ads have largely focused on building brand awareness, a significant part of search advertising expenditure is nowadays also focused on generating brand awareness and not only towards directly generating sales. More generally, the fact that the ad serving tools helping advertisers to assess their return on investment are progressively converging across different types of ads reinforces the conclusion according to which all kinds of ads could be substitutable. The main reason for the limited availability of metrics in some cases seems to originate more from self-imposed policies than technical37 or regulatory reasons38.
It can, therefore, be inferred that, from an advertiser's point of view search and non-search ads can be considered substitutable to a certain extent.
From a publisher's perspective, the possibilities of substitution between search and non-search ads are entirely different. Indeed, publishers can add a search tool on their web page (that is to say a small search box appearing on the homepage of a publisher) and thereby generate additional revenues by sharing the revenues of advertisements appearing next to the search results. Yet these search results generally appear on a new web page not forming part of the
Regulation concerning privacy protection and advertising is weaker in the field of online media than in the field of more traditional offline media. Its enforcement would also be much more challenging because of the limitations of local rules in addressing the global character of internet.