Garrett McGrath returns to Prebid.org as president on 15 September

Prebid.org has a new president. Garrett McGrath takes the job on 15 September, replacing Mike Racic, who stepped down after being the group first president. AdExchanger reported the move on 10 September, and Prebid.org confirmed it in its own announcement.

Thirty days of handover with Mike Racic

The two men will share the job until 15 October. After that McGrath runs it alone. He has also said his first 90 days will be a listening period rather than a decision period.

Five years as chairman, then a conflict of interest

McGrath is not new to the organisation. He chaired Prebid.org for five years while working as senior vice president of product at Magnite. He gave up the chair in June 2026, because the rules do not let someone hold it after leaving a member company role. Joel Meyer, chief technology officer at OpenX, was elected chairman in August.

Agentic AI standards and identity top the list

McGrath named three areas of work. The first is standards for agentic AI, meaning software that buys and sells on its own, where Prebid wants to stay neutral between rival protocols. The second is deal curation and shared publisher data. The third is identity, through the User ID Module and SharedID.

Prebid.org started in 2015 and keeps the open-source code that many publishers use to run their own auctions. As McGrath put it, “if advertising pays for the internet, then Prebid is critical infrastructure”.

What Prebid decides shows up in publisher auctions

This is not a personnel note for insiders only. Prebid code sits between a publisher page and the companies bidding for its space, so a change in the rules there changes what a buyer sees. Two things are worth watching over the next year. Whether Prebid picks a side on agentic buying, and whether identity work makes targeting easier once third-party cookies keep shrinking. Both feed straight into open-web prices, the same market where Trade Desk cut 15% of its staff as growth slowed. Media owners are also changing what they sell there, as YouTube did when it opened alcohol ads to personalised targeting.