Magnite and PubMatic Sign ChatGPT Ad Deals as OpenAI Builds Partner Bench

Magnite and PubMatic have signed deals to fill unused ad space in ChatGPT, The Information reports, joining an ad-tech roster that already includes LiveRamp, Criteo, StackAdapt and Amazon Ads. The signings mirror the early chapters of every walled-garden playbook: open inventory to third-party intermediaries first, then pull the walls back up once scale is secured.

The pattern has precedents. YouTube allowed third-party ad serving for a time. Facebook bought the Atlas ad server and quickly shuttered it. Amazon Prime ran a DSP partner program with full third-party programmatic visibility until partner dataxu was acquired by Roku, and The Trade Desk — the program's only other vendor — was quietly cut off months later.

Who is building OpenAI's ad partnerships?

Samantha Jacobson, OpenAI's VP of partnerships, was until recently The Trade Desk's chief strategy officer. She announced her departure in May amid a wider exodus of senior executives at TTD and now helps build partnerships at one of the most coveted new media platforms. Whether OpenAI's intermediaries stay welcome once first-party tooling matures is the question none of the deals answer.

Why are celebrities endorsing prediction markets?

Kalshi, Polymarket and Novig are trading on celebrity reputations to become household names. Polymarket launched a September campaign featuring LeBron James, Derek Jeter, Eli Manning, John Leguizamo, Alexandra Daddario, Spike Lee and Emily Ratajkowski; Novig built a campaign around actress Sydney Sweeney.

The logic for the platforms is clear. A March Ipsos poll found only 20% of respondents were familiar with prediction markets despite extensive marketing, Amanda Mull writes at Bloomberg. The logic for the celebrities is less so: among consumers who do know the platforms, 40% viewed them as bad for society and 60% called them no different from gambling.

Mull argues the concept of "selling out" is officially dead, and that in an era of devoted fandoms, "celebrities and influencers announce new ad campaigns and brand sponsorships to excited, congratulatory fans as though they are awards." Her explanation for the Polymarket pile-on: "Maybe that's why so many people agreed to be in that Polymarket ad at the same time – safety in numbers."

How much Google search budget is moving?

Ad buyers are scrutinizing Google search budgets as AI Overviews drive lower click-through rates, Digiday reports — the ads underperform even as cost-per-click rates rise. One marketing expert told Digiday he has seen advertisers reallocate 10% to 30% of their Google search budgets into other channels, including Meta, ChatGPT, and Google's own AI Max, YouTube and Demand Gen.

The shift tracks Alphabet's own numbers. Last week Alphabet's stock dropped more than 10% after its earnings report showed slowing search ad revenue growth, which SVP and 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 alone.

Also this week

• Publicis officially closed its acquisition of LiveRamp.
• AdImpact data shows CTV ad spending overtook cable for the first time during this midterm cycle, per Adweek.
• Anthropic made $17 billion in revenue last quarter but plans to spend more than $895 billion in coming years, Bloomberg reports.
• "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 publications are suing browser maker Brave over AI scraping and paywall bypassing.
• An anonymous group of ad executives wants the UK government to do more to stop the industry funding hate speech on social media, The Media Leader reports.

On the move

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

The through-line: OpenAI is buying credibility with ad-tech partners it may not need in two years, and Google is spending down a $127.6-billion-quarter cushion against the same AI shift its buyers are fleeing. By Amara Osei.