The "vast majority" of the U.K.'s thousands of publishers and advertisers use Google's technology in order to bid for and sell space to display ads in a market where players were spending £1.8 billion annually as of a 2019 study, according to the CMA.
The regulator added that it is also "concerned that Google is actively using its dominance in this sector to preference its own services." So-called "self-preferencing" of services by technology giants is a key concern for regulators scrutinizing these companies.