Discrepancies in Transaction ID standards fuel doubts about programmatic transparency
In the dynamic world of programmatic advertising, a controversy has arisen surrounding the implementation of Transaction ID standards. This dispute, which came to light in August 2025, has been analysed by Brian O'Kelley, founder and CEO of Scope3, and has sparked discussions within the Interactive Advertising Bureau (IAB).
The controversy centres around changes in Prebid's implementation of transaction ID standards, which have been criticised by the IAB Technology Laboratory for violating OpenRTB specifications. This technical dispute has raised concerns about data privacy and revenue impact for publishers, as the changes eliminate cross-exchange visibility for identical auction opportunities.
Privacy considerations motivated the implementation modifications, according to discussions in the Prebid community. Publishers expressed concerns that unified transaction IDs could enable buyers to combine bid requests across different sellers, potentially exposing identifier connections that publishers preferred to keep separate.
The IAB Technology Laboratory approved the Community Extension for per-impression transaction IDs in OpenRTB in June 2022, and Prebid implemented initial transaction ID support following OpenRTB specifications in the same year. However, recent changes in Prebid's implementation have stirred controversy.
Publishers and supply-side platforms (SSPs) have expressed concerns about DSP optimization potentially reducing bid values and compromising revenue streams. The changes in Prebid's implementation have eliminated cross-exchange visibility that the OpenRTB specification originally intended to provide.
The controversy embodies fundamental questions about programmatic advertising's future structure, transparency requirements, and regulatory oversight necessity. According to O'Kelley's assessment, the regulatory implications appear significant. He predicts the Department of Justice will recognize monopolistic behaviours and implement remedial measures.
This controversy comes amid significant programmatic advertising growth. The latest State of Programmatic Report from Comscore reveals that 72% of marketers plan to increase programmatic investment in 2025. In July 2025, The Trade Desk joined the S&P 500 index following strong programmatic growth.
The controversy could accelerate market consolidation and direct relationships, with major platforms developing proprietary solutions, as predicted by Brian O'Kelley. This is evident in Microsoft's decision to sunset Xandr DSP, removing one of the industry's most transparent platforms, AppNexus, which was recognized for providing unprecedented visibility into fee structures and money flows throughout advertising supply chains.
The controversy also has regulatory implications. In January 2023, the Department of Justice filed an antitrust suit against Google over digital advertising conduct. The resolution requires collaboration among technical standards organizations, implementation platforms, publishers, advertisers, and potentially regulatory authorities.
In March 2023, Senator Mike Lee introduced the first version of the AMERICA Act in the 118th Congress. The Act aims to increase transparency in digital advertising, addressing concerns about data privacy and market competition.
The ANA Programmatic Media Supply Chain Transparency Report, published in December 2023, revealed that only 36% of budgets reach valid impressions. This underscores the need for transparency and accountability in the programmatic advertising industry.
On July 25, 2025, Meta announced its withdrawal from EU political advertising citing TTPA compliance challenges. This move further emphasises the need for clarity and standardisation in the programmatic advertising industry.
In response to the controversy, the IAB engaged in discussions with Brian O'Kelley and published an official statement in August 2025. The statement underscores the importance of adhering to OpenRTB specifications and maintaining transparency in the programmatic advertising industry.
As the programmatic advertising industry continues to grow, it is crucial that standards are upheld and transparency is maintained. The controversy surrounding Transaction ID standards serves as a reminder of the need for ongoing dialogue and collaboration among all stakeholders in the industry.
