In today’s MadTech Daily, we cover Google’s ad tech trial nearing a judge’s decision, Amex and Duolingo launching ad platforms, and Mozilla partnering with Index Exchange.

Google’s Ad tech trial nears Judge’s decision

The remedy phase of the US Department of Justice’s antitrust case against Google’s advertising technology operations concluded on October 3, marking the government’s effort to address monopolistic control over the digital ad ecosystem. Over ten days of courtroom debate, the DOJ and Google presented starkly different visions for how to restructure a business that has long dominated both the buying and selling sides of online advertising. The proceedings focused not on Google's guilt already established but on the appropriate corrective measures to restore competition.

Government attorneys advocated for sweeping structural changes, including the divestiture of Google’s ad exchange, the core system that connects buyers and sellers of digital ad space. They also proposed making the auction code used by publisher tools publicly available and suggested further divestments if competition fails to improve.

Google, meanwhile, has countered with a suite of behavioral remedies, such as contract adjustments and improved interoperability with rival platforms, suggesting that a breakup is unnecessary.

The next phase of the case begins with post-trial briefs expected by early November, followed by closing arguments later that month. Judge Brinkema’s final ruling is anticipated in 2026, with observers predicting a mix of conduct remedies and potential structural changes to address Google’s ad tech dominance.

Amex and Duolingo launch ad platforms

American Express has officially made its move into the commerce media sector with the launch of Amex Ads, a new advertising platform that taps into its extensive pool of first-party data. The platform enables brands to purchase display inventory across Amex-owned properties starting with AmexTravel.com and target audiences using insights drawn from the spending and travel behaviours of its 34 million US consumer cardholders.

Meanwhile, Duolingo has introduced Duolingo Ads, a direct ad sales platform that allows marketers to buy premium in-app inventory and custom ad formats. With Duolingo Ads, the company aims to offer advertisers a more curated, brand-safe environment, leveraging its unique characters and storytelling style to create engaging, animated ad experiences. Now, the company is betting on branded, character-driven ad experiences that fit seamlessly with Duolingo’s playful tone.

Mozilla partners with Index Exchange

Mozilla has announced a strategic partnership with Index Exchange to introduce programmatic advertising to its Firefox browser, marking a significant shift in how the company approaches monetisation. The collaboration, unveiled during Advertising Week New York 2025, will enable advertisers to access Firefox’s New Tab audience through Private Marketplace (PMP) deals facilitated exclusively by Index Exchange. 

Mozilla executives emphasised the importance of transparency and control, noting that the new model is designed to enhance both audience experience and campaign performance. Suba Vasudevan, Chief Operating Officer of Mozilla.org, highlighted the need for a new foundation in online advertising, one that prioritises trust not just in creative content, but in the platforms where ads are delivered. “By engineering trust into the advertising environment itself, we’re creating a higher-quality audience experience and a stronger performance channel for brands,” she added.