Advertisers Can Now Trace Who Sees Their Bid Requests
▼ Summary
– IAB Tech Lab proposed an update to the OpenRTB SupplyChain Object (schain) to expose both the financial and technical journey of a bid request, available for public comment through Aug. 21, 2026.
– The current schain standard only reveals companies in the payment flow, not all entities that process, route, or transmit a bid request, which the update aims to change.
– The update challenges the assumption that shorter supply chains are always better, allowing buyers to evaluate each participant’s contribution rather than just counting intermediaries.
– Greater transparency could expose redundant infrastructure and intermediaries adding little value, potentially creating challenges for some vendors while benefiting those delivering measurable value.
– The proposal incorporates technical custody information into the existing schain framework, with companies not in the payment flow receiving an hp=0 designation, and IAB Tech Lab plans to publish rollout guidance for staged testing.
For years, programmatic media buyers have been able to see exactly who gets paid in a transaction. What remained far less visible was the full list of companies that handled a bid request before it ever reached their desks. IAB Tech Lab is now proposing a major update to change that.
The organization has unveiled a proposed revision to its OpenRTB SupplyChain Object, commonly known as schain. This update, dubbed SupplyChain v1.1, aims to expose both the commercial and technical journey of every bid request. If adopted, it could fundamentally alter supply-path optimization (SPO) by giving buyers a clear view of not just who earned revenue from a deal, but every entity that touched the request along the way. The proposal is open for public comment until August 21, 2026.
Moving beyond the money trail
The current schain standard provides visibility into the financial side of a transaction, identifying companies that are part of the payment flow. However, it does not necessarily reveal every firm that processes, routes, enriches, or transmits a bid request. This distinction has become increasingly critical as programmatic infrastructure grows more complex. A single impression opportunity may pass through ad servers, Prebid implementations, SDKs, server-side ad insertion platforms, wrappers, and numerous other technologies before reaching a buyer.
Under the new proposal, buyers would gain visibility into those technical participants as well. “This is one of the most significant transparency enhancements to the digital advertising supply chain in years,” said Anthony Katsur, CEO of IAB Tech Lab, in a statement. The goal is to provide buyers with a more complete record of the inventory available on the open internet.
Why advertisers should care
This proposal arrives at a time when advertisers are aggressively searching for ways to reduce waste and optimize their supply chains. Much of the industry’s SPO work has focused on finding the shortest path between publisher and buyer, operating under the assumption that fewer intermediaries lead to greater efficiency. SupplyChain v1.1 challenges that assumption directly.
Longer supply chains are not automatically worse, provided buyers can see and evaluate every participant. This idea carries broader implications than the technical update itself. Instead of simply counting intermediaries, buyers could assess what each participant actually contributes. A supply path with more participants might deliver more value than a shorter one if every entity performs a useful function and the process remains fully transparent. The conversation shifts from “How short is this path?” to “Who participates in this path and why?”
Transparency creates winners and losers
Not every company in the ecosystem will welcome this shift. Advertisers have spent years pushing for greater visibility into how inventory is packaged, routed, and sold. More transparency could expose redundant infrastructure, duplicate bid requests, and intermediaries who add little value. That scrutiny could create significant challenges for vendors struggling to articulate their role in the transaction chain.
At the same time, companies that deliver measurable value gain a stronger opportunity to distinguish themselves from competitors. The proposal turns technical participation into something buyers can evaluate rather than something hidden behind the scenes. The working group behind the proposal evaluated several implementation approaches before selecting one that incorporates technical custody information directly into the existing schain framework. Companies that take technical custody of a request but do not participate in the payment flow would receive an `hp=0` designation.
According to IAB Tech Lab, this approach preserves compatibility with the existing standard while expanding visibility into requests as they move through the ecosystem. The organization also expects longer schains as transparency increases. To support adoption, IAB Tech Lab plans to publish rollout guidance encouraging SSPs and DSPs to conduct staged testing, validate parsing behavior, monitor bid health, and gradually scale traffic using the new specification.
(Source: MarTech)
