The UK Competition and Markets Authority (CMA) has initiated an investigation into Google, suggesting that the tech giant may be engaging in anti-competitive practices within the online advertising technology market.

The CMA alleges that since 2015, Google has abused its dominant position by favoring its AdX ad exchange over competitors and publishers.

As part of the investigation, the CMA will review Google's response before making a final ruling, which could result in fines of up to 10% of Google's global turnover.

This investigation aligns with ongoing inquiries by the U.S. Department of Justice and the European Commission, both of which are also scrutinizing Google's advertising practices.

In the U.S., Google is facing antitrust litigation for allegedly maintaining a monopoly in digital advertising, with the DOJ having filed a lawsuit earlier this year.

Google has publicly disputed the CMA's allegations, asserting its commitment to providing value to its partners and plans to respond to the charges.

Juliette Enser, the CMA's interim executive director, emphasized the importance of competition in the advertising sector, which is vital for publishers and advertisers who rely on ad revenue.

The CMA's findings suggest that Google's ad buying tools and publisher ad server have strengthened its AdX exchange, making it challenging for rivals to compete effectively.

Allegations against Google include manipulating bids to favor AdX in auctions, which restricts opportunities for competing ad exchanges.

Plaintiffs have claimed that Google's practices have reduced revenues for online content publishers by increasing fees on its ad platforms while simultaneously decreasing their ad income.

Despite the scrutiny, analysts have indicated that Google Ad Manager represented only a small fraction of Alphabet's overall revenue, suggesting limited risk to the company's broader business.

As Google prepares for its second major antitrust trial this year, the focus will be on its ad tech practices and the potential divestment of Google Ad Manager.