‘Creating more complexity’: Prebid’s transaction ID change stirs debate and confusion

Prebid’s move to render its transaction ID (TID) unworkable across exchanges has sparked fierce debate in the ad tech world — and left many scratching their heads. The change makes each TID unique to a single bidder, meaning it no longer works across exchanges.

IAB Tech Lab CEO Anthony Katsur released a statement pushing back against the change, saying that it “risks undermining the integrity and consistency of open technical standards that are critical to interoperability across the programmatic ecosystem.”

Now that the dust has settled on the debate — which mostly played out on LinkedIn over the last couple weeks — some industry observers who spoke with The Current remain puzzled by the move.

Until now, TIDs have helped media buyers identify duplicate bid requests. In theory, that made it easier to avoid paying twice for the same impression, clean up the advertising supply chain, highlight premium quality inventory and bring some discipline to the market.

“If we land on the conclusion in the initial debate that bid duplication is something we’d like to provide more transparency into, there isn’t an easy industry agreed-upon button to facilitate that transparency,” Gareth Glaser, author of the Substack publication Gareth Hates AdTech, tells The Current.

So why would Prebid cripple that ability?

Prebid didn’t respond to a request for comment, but ad tech guru Ari Paparo reported that privacy played a role, resulting from Prebid’s work with outside consultants on the issue.

Prebid had previously underscored this concern in a comment on LinkedIn, saying TIDs could pose a risk to user privacy.

But some in the industry aren’t buying that, according to people The Current spoke to.

“Without that signal, reselling and bid duplication are harder to detect, CPMs get inflated without adding real value and it creates a dynamic where publishers using shady tactics monetize better than the high-quality publishers who should be winning,” says Vlad Chubakov, associate director of programmatic at Delve Deeper.

Adam Heimlich, CEO at Chalice, put it more bluntly: “It’s about tricking buyers into bidding against themselves.”

‘Bad behavior is rewarded’

According to Heather Carver, CRO at Freestar and a Prebid board member, some publishers are concerned that TIDs can be stitched across supply-side platforms (SSPs) like a device graph, allowing buyers to shift spend to the cheapest route.

Glaser offers a devil’s advocate spin, noting that anything that helps publishers make more money could be perceived as a good thing.

But, he cautions in his newsletter, some publisher arguments could also be shortsighted, because “we don’t know what the knock-on effects of these techniques are in terms of making programmatic work badly.”

He raises a bigger question: “At what point in a functional ecosystem does replicating bid requests for the same opportunity become a fundamental flaw in the construction of the technology stack and not a feature for publishers?”

Sure, in the short term it could get publishers more spend, says David Nyurenberg, SVP of digital at InterMedia Advertising. But the trade-off is steep in this scenario, he says, because “bad behavior is rewarded.”

In the longer term, it “creates less trust in programmatic,” he adds.

“SSPs can trick the supply path, and drive CPMs up because it seems like there’s more inventory than there actually is,” Nyurenberg says.

‘More complexity when we need less’

Transaction IDs were a gentle way to “discipline the market,” Heimlich says, but now the status quo will be hazy.

“All this is doing is creating more complexity in the programmatic ecosystem when we need less,” Nyurenberg adds.

Eric Tilbury, senior director of ad operations at Inuvo, thinks the answer is on the buy side to prioritize value over volume.

“The reason to duplicate is for one reason only and that’s to make more money,” he says. “It looks like there is a ton of demand, which DSPs flock to, and their bidding behavior favors that inventory because of it.”

Chubakov concurs that the onus is now on buyers.

“The only path forward is incentive alignment,” he says. “Buyers have to reward publishers who pass deduplication signals so that transparency actually becomes the more profitable choice.”