EU antitrust regulators are launch a formal investigation into Alphabet unit Google’s digital advertising practices, people familiar with the matter confirmed.
The move is likely to come before the end of the year.
Google made $147 billion in revenue from online ads last year, more than any other company in the world.
Ads on its own properties, including search, YouTube and Gmail, accounted for the bulk of sales and profits.
About 16% of revenue came from its display or network business, in which other media companies use Google technology to sell ads on their website and apps.
Earlier this year, the EU had sent a questionnaire to Google rivals and third parties.
The questionnaire probed if advertisers receive rebates when they use Google intermediaries which allow advertisers or media agencies to buy advertising inventory from many sources.
The EU competition enforcer has in the last decade slapped fines totalling 8.25 billion euros ($9.8 billion) on the world’s most popular internet search engine for blocking rivals in online shopping, Android smartphones and online advertising.