The CMA will examine three key parts of the ad tech stack; Google owns the largest service provider in each of these parts of the chain:

• Demand-side platforms (DSPs)
• Ad exchanges
• Publisher ad servers

The regulator will assess whether Google limited the interoperability of its ad exchange with third-party publisher ad servers and/or contractually tied these services together, making it more difficult for rival ad servers to compete. It will also investigate whether Google’s publisher ad server and its DSPs to illegally favour its own ad exchange services, while taking steps to exclude the services offered by rivals.

Andrea Coscelli, the CMA’s Chief Executive, said: ‘Weakening competition in this area could reduce the ad revenues of publishers, who may be forced to compromise the quality of their content to cut costs or put their content behind paywalls. It may also be raising costs for advertisers which are passed on through higher prices for advertised goods and services’.

A draft Bill to give the CMA more powers to govern the behaviour of big tech firms, through the Digital Markets Unit, was recently announced in the Queen’s Speech.