Prebid Summit Reignites After The Trade Desk's Code Fork

The Trade Desk forked Prebid's core code one year ago over Transaction ID data collection — and at Tuesday's Prebid Summit in New York City, that rupture was still producing sparks on stage.

Scope3 CEO Brian O'Kelley confronted TTD's acquihired Sincera co-founders during a live podcast about Prebid's history. O'Kelley accused TTD of having "f***ing forked" Prebid a year ago. "Thank you for not contributing," he said. "Thank you for trying to split off your own motivation and do something worse for this community. You two did it." O'Sullivan, one of the Sincera founders, replied: "Brian, always a pleasure chatting with you."

Why the tension is structural, not personal

Prebid started as a publisher-oriented organization. The Trade Desk's presence last year, including a main-stage keynote from CEO Jeff Green, marked Prebid's growing comfort with buy-side stakeholders. At the same time, Prebid and the IAB Tech Lab navigated a fraught moment, because Prebid was expanding its own open-source ad standards into territory traditionally owned by the Tech Lab.

Allies, rivals and frenemies now jostle together in a constantly shifting mix of antagonism and support, which makes Prebid one of the few remaining crucibles in programmatic.

What happened in the Google Ad Manager working group?

A breakout session on ad server integration showed the mechanism at work. Microsoft Advertising engineer Brian Sardo pitched his working group's design for integrating a Prebid ad server with Google Ad Manager. Cross-talk from roughly twenty contributors ran so thick that Sardo could not finish his presentation. He was not bothered; he said the debate is exactly the point.

The group is moving forward with a proposal Sardo supports. Only at the end did it become clear that Joel Meyer, Prebid board chairman and OpenX CTO, had authored the losing alternate proposal.

Patrick McCann, SVP of research at Raptive and chair of Prebid's JavaScript working group, noted that Google employees were present in the room. That did not stop the group from seriously discussing whether and how Prebid should prepare for GAM (Google Ad Manager) to evade the monopoly remedies set by US District Court Judge Leonie Brinkema. Google's delegation maintained a friendly but stoic silence.

The IAB Tech Lab's Hillary Slattery also attended, pressing for a server-side overhaul of the supply chain and urging adoption of the Tech Lab's Trusted Server technology.

How does iOS 27 hit identity companies?

On the main stage, Ryan Teshima-McCormick, chief business officer of MediaWallah, said Apple's iOS 27 update had derailed the panel's planned discussion. The update blocks some of the largest identity and data companies from operating on Apple devices running the new version.

LiveRamp and ID5, both represented on the panel, were unconditionally blocked by Safari WebKit in iOS 27. Experian and 33Across, the other panelists, were also adjusting to a potential world without data collection or ad targeting on Apple hardware.

"For everyone in this room that's been trying to understand and manage their data partnership strategies, specifically as it pertains to signals, while literally the ground is moving under our feet," Teshima-McCormick said, "I think it's important to just throw it to anyone on our panel here that would want to share any advice on how to navigate."

Neither the ID5 nor the LiveRamp representative offered a candid opinion on stage. Off stage, executives could be overheard fighting to hold or gain share amid the iOS change and Publicis' acquisition of LiveRamp.

Pressed further by O'Kelley over "having the nerve to come on-stage and talk about innovation," O'Sullivan pivoted to highlight TTD's contributions to the publisher side. That kind of fraught but illuminating exchange has become rare at ad tech events — and it is the reason Prebid remains the place where difficult questions get stared down and decisions get made.