The European Commission, the executive arm of the EU, reached a preliminary conclusion that Google is dominant in the European market for publisher ad servers and for programmatic ad-buying tools for the open web.
The commission also said Google has abused this dominant position since at least 2014.
"The Commission's preliminary view is therefore that only the mandatory divestment by Google of part of its services would address its competition concerns," EU competition chief Margrethe Vestager said in a statement.
"Our preliminary concern is that Google may have used its market position to favour its own intermediation services.
If confirmed, Google's practices would be illegal under our competition rules,"Google was not immediately available for comment when contacted by CNBC.
Persons:
Margrethe Vestager, Vestager
Organizations:
European Union, European Commission, EU, Google, CNBC
Locations:
Brussels, Belgium