Magnite and PubMatic Sign ChatGPT Ad Deals as OpenAI Builds Its Walled Garden

OpenAI has signed Magnite and PubMatic to fill unused ChatGPT ad space, The Information reports, adding two supply-side platforms to a partner roster that already includes LiveRamp, Criteo, StackAdapt and Amazon Ads.

The move mirrors a familiar platform playbook. YouTube once allowed third-party ad serving before closing the doors. Facebook bought the Atlas ad server and quickly shut it down. Amazon Prime ran a DSP partner program with full third-party programmatic visibility until dataxu was acquired by Roku, and The Trade Desk — the program's only other vendor — was quietly cut off months later.

Is OpenAI repeating the walled garden cycle?

The partner push carries a pointed subplot. Samantha Jacobson, OpenAI's VP of partnerships, was until recently The Trade Desk's chief strategy officer. She announced her departure in May amid TTD's exodus of senior executives. Now she helps build partnerships at one of the most coveted new media platforms in the world.

For advertisers, the implication is straightforward: third-party access to ChatGPT inventory exists today, but history suggests it may not last. The early pages of every walled garden playbook involve opening inventory to intermediaries — before the walls go back up.

Why are celebrities endorsing prediction markets?

Kalshi, Polymarket and Novig are trading on celebrity reputations to become household names. A March Ipsos poll found just 20% of respondents were familiar with the platforms, despite extensive marketing.

Polymarket launched a star-studded campaign in September featuring LeBron James, Derek Jeter, Eli Manning, John Leguizamo, Alexandra Daddario, Spike Lee and Emily Ratajkowski. Novig ran a headline-grabbing campaign with actress Sydney Sweeney.

Amanda Mull at Bloomberg writes that the concept of "selling out" is officially dead. Among consumers familiar with prediction markets, the same Ipsos poll found 40% viewed them as bad for society and 60% thought they were no different from gambling.

"Celebrities and influencers announce new ad campaigns and brand sponsorships to excited, congratulatory fans as though they are awards," Mull writes. "Maybe that's why so many people agreed to be in that Polymarket ad at the same time — safety in numbers."

How much search budget is leaving Google?

Ad buyers are scrutinizing Google search budgets as AI Overviews drive lower click-through rates, Digiday reports. Ads are underperforming despite higher CPC rates.

One marketing expert told Digiday that some advertisers are reallocating 10% to 30% of their Google search budget into other channels. Others report clients moving money into Meta and ChatGPT, or into other Google products including AI Max, YouTube and Demand Gen.

The shift mirrors trends at Google itself. Last week, Alphabet's stock dropped over 10% after its latest earnings report revealed slowing search ad revenue growth, which Chief Business Officer Philipp Schindler attributed to lower monetization of AI Mode.

Google maintains that AI-powered campaigns and a more "conversational" search experience will deliver greater advertiser value long term — a fair bet for a company that earned $127.6 billion in Q3 this year alone.

In brief

• Publicis officially closed its acquisition of LiveRamp.
• AdImpact data suggests CTV ad spending overtook cable for the first time during this midterm cycle.
• Anthropic made $17 billion in revenue last quarter but plans to spend more than $895 billion in coming years, per Bloomberg.
• NFL RedZone anchor Scott Hanson says league executives are to blame for commercials added to the channel in 2024 and its rising ad load since.
• The New York Times, Chicago Tribune and other publishers are suing Brave's makers over AI scraping and paywall bypass.
• An anonymous group of advertising executives wants the UK government to do more to stop the industry funding hate speech on social media.

On the move

OpenX hired Robert Horler as its new CEO. Netflix brought on Darshan Kantak as VP of ads platform.

If the walled garden pattern holds, advertisers wanting programmatic access to ChatGPT inventory may find their window narrower than the current partner list suggests.