Magnite-Led Consortium Completes First Phase of Publisher First-Party Segments Initiative

Magnite Team

June 29, 2021 | 5 min read

Provides Media Owners With a Transparent, Scalable and Standardized Solution Based on Publisher First-Party Data

June 29, 2021 – Magnite, the world’s largest independent sell-side advertising platform, today announced the completion of the first phase of a Publisher First-Party Segments Initiative which addresses the needs of buyers and sellers in a cookieless environment. The initiative already handles over three billion transactions daily and has over 30 participants, including media owners and members of the buying community. 

In response to the eventuality of third-party cookies no longer being a viable identity and targeting solution in the future, participating publishers are testing Publisher First-Party Segments to provide buyers with scalable audience targeting opportunities, while safeguarding user identity and browsing history. The first phase of this initiative focused on helping publishers define and assemble First-Party Segments using existing IAB Tech Lab industry standards, establish a testing framework, and execute real-time transactions against these seller-defined audiences without the use of third-party cookies.

This month, Magnite moved this effort formally into where the project will expand under the guidance of the taxonomy task force and IAB Tech Lab’s Addressability working group. To further iterate and scale, the Publisher First-Party Segments Initiative is expected to adopt the IAB Tech Lab’s Seller-Defined Audience specification, which was incubated last year within IAB Tech Lab’s global Project Rearc initiative.

“In order to validate the efficacy of a cookieless identity solution, we reached out to a group of leading publishers, DSPs and buyers with a proposal to collaborate around publisher first-party segments,” said Garrett McGrath, VP of Product Management at Magnite. “The rapid launch and testing with real advertising budgets speaks volumes for what we can accomplish when the industry comes together. The resulting Publisher First-Party Segments Initiative presents publishers with an addressability approach that has both high accuracy and scale through federated segments.”

The participants of this initiative include Adform, CafeMedia, Condé Nast, Future Publishing, Goodway Group, Havas, Hearst Magazines, IBM Watson Advertising, Insider, Maven, Meredith Corporation, Merkle|DWA, MiQ, News Corp, Permutive, Publishers Clearing House (PCH), PubMatic, among others.

“Solutions based on publisher first party data provide a privacy-safe, user-friendly solution to a post-third party cookie world,” said Stephanie Layser, VP of Advertising Technology at News Corp. “By not tracking and targeting cross-domain, users don’t have to feel like ads are ‘following’ them around the internet and we’re providing solutions that tie data to media so that publishers get the true value of their engagement. Folding this initiative into Prebid is the right way to go – keep it open source and make it standard.”

“As third-party cookies fade from use in the near future, it’s critical that the industry works toward building publisher-controlled and privacy-preserving technologies,” said Paul Bannister, Chief Strategy Officer at CafeMedia. “The First-Party Segments Initiative is a fantastic step forward for cross-company collaboration and building a more sustainable future.”

“With our industry currently in an evolution period and actionable first-party data being increasingly critical to all marketers, The Weather Company and IBM Watson Advertising are leaning in with companies like Magnite to innovate,” said David Olesnevich, Head of Product at IBM Watson Advertising. “These collaborations expedite our experimentation and learning opportunities, allowing for next gen solutions with tremendous value to be realized. We look forward to continuing to strengthen this initiative with foundational ad-tech integrations.”

“Meredith believes that the future of programmatic advertising lies in balancing the requirements of advertising use cases with the privacy of consumers,” said Nicole Lesko, COO & Data Strategy at Meredith Corporation. “FPS leverages seller-defined audiences to deliver targeting at scale to advertisers without the privacy problems of deterministic identifiers in the bidstream.”

“Havas is an avid supporter of this initiative that offers a much needed alternative to targeting without third party cookies, whilst providing access to rich publisher data that enables us to create more meaningful connections to users for our brands,” said Tom Grant, SVP, Group Director, Investment Operations at Havas Media.

“Goodway Group feels it is incredibly important for buyers to support publisher centric identity solutions,” said Amanda Martin, SVP of Corporate Development and Strategic Partnerships at Goodway Group. “The collaboration across leading publishers, DSPs and buyers is a perfect example of how the industry can come together to create viable solutions to protect consumers’ privacy and meet advertisers’ needs.” 

“In a cookieless future, marketers are going to need to tap into both high quality authenticated data and scalable anonymous data on both the open and closed web,” said Paul Silver, Global Chief Strategy Officer, MiQ. “Scaling publisher first party data to a level of industry-wide interoperability through sustainable and privacy-compliant practices is one of the key ways to make this possible, so at MiQ we are excited to be involved in these early tests and see further adoption of this solution.” 

To learn more about this initiative and how to participate, please reach out to

About Magnite

We’re Magnite (NASDAQ: MGNI), the world’s largest independent sell-side advertising platform. Publishers use our technology to monetize their content across all screens and formats including CTV, online video, display, and audio. The world’s leading agencies and brands trust our platform to access brand-safe, high-quality ad inventory and execute billions of advertising transactions each month. In April 2021 we acquired SpotX to further enhance our CTV business and better help our clients in this rapidly growing market. Anchored in sunny Los Angeles, bustling New York City, mile high Denver, historic London, and down under in Sydney, Magnite has offices across North America, EMEA, LATAM, and APAC.

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