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Episode 137: The Big Debate Around Transaction IDs with Chris Kane and Mike O’Sullivan

Host: Ari Paparo
Guests: Chris Kane (Jounce Media), Mike O’Sullivan (ex-Sincera, now The Trade Desk)
Date: August 29, 2025

Brief Overview

This episode centers on transaction IDs (TIDs) in programmatic advertising—a technical topic with far-reaching implications for publishers and buyers alike. Prompted by a debate between Mike O’Sullivan and Chris Kane, the podcast explores the pros and cons of publishers passing transaction IDs in ad auctions, with a timely intervention: Prebid, the open-source advertising technology, made a sudden change undermining the value of TIDs mid-recording. The discussion delves deep into motives, incentives, market power, and the evolving tug-of-war between publisher opacity and buy-side transparency.

Key Topics and Discussion Points

1. What Is a Transaction ID, and Why Now?

[02:32, Ari Paparo explains]

• Definition: A unique identifier (TID) assigned per ad auction that can persist across the “spider’s web” of programmatic connections.
• Purpose: Lets buyers detect if the same impression is being offered multiple times by different SSPs (supply-side platforms), helping avoid duplicate auctions and making supply chains more transparent.
• Controversy: TIDs are part of the OpenRTB spec but are optional. When The Trade Desk (TTD) signals it may devalue inventory without TIDs, publishers perceive this as coercion.

2. Origins of the Debate

[10:07, Mike O’Sullivan]

• Mike’s “innocuous” LinkedIn post asking for genuine arguments against TIDs triggered a flood of publisher backlash.
• Chris Kane’s Take: “The Trade Desk is starting to use TID to inform bidding, and the absence of a TID could hurt a publisher’s value. That’s what suddenly made it a top issue.” [12:32]

3. Publisher Concerns

• Data Leakage/Regulatory Fears: Not the main issue, but some publishers worry deterministic keys could breach contractual or regulatory lines. [13:54, Chris Kane]
• Potential Loss of Revenue: If TIDs let DSPs (demand-side platforms) identify duplicated or “inflated” inventory, publishers overleveraging auction duplication may see revenue fall. [15:19ff]
  • “If DSPs really want this, it’s probably going to reduce revenue in some way.” (Ari, 15:24)
  • “I think publishers who are doing a lot of request duplication will see their revenue drop.” (Mike, 15:51)

4. Buy-Side Perspective

• Transparency as a Signal: High-quality publishers (less duplication) are getting under-monetized; TID helps correct this “prisoner’s dilemma.” (Mike, 15:51)
• Quantifying Duplication: Example: 1 Roku device, 1 SSP, 1 family sent 1.7 million bid requests per day—equivalence of 14,000 hours of ads. (Mike, 18:09)
  • “If you watched all those ads back to back, it would take you until April 2027.”
• Downstream Effects: Over-duplicated auctions hurt buyer performance, which drives advertiser budgets to walled gardens (platforms like Google or Meta). [24:08]
  • “Performance on the Open Internet suffers… performance degrades, budgets go away.”

5. Prebid's Breaking Change—Live News

• [21:01, Mike O’Sullivan]: “A breaking change was introduced into Prebid that… effectively breaks transaction IDs.” Now, TIDs are unique per exchange/SSP, not per auction—undermining the point.
• Implications: Publishers lose the option to “opt in,” and buy-side transparency is dramatically reduced.
  • “The choice was made for you by Prebid. It does not exist anymore. It’s a real miss.” (Chris, 27:31)

6. Market Power—and Trust Issues

• Publisher Fears: Not just about economics or data leaks but “deep scars” from previous buy-side (Google) dominance. Many fear TTD wielding similar power.
  • “I’m very confident publishers are scared of The Trade Desk.” (Chris, 33:59)
• Mike's Defense: TTD only signals what it values, doesn’t “strong-arm.” “Trade Desk just needs a clean auction to win.” [31:52]
  • “There’s no secret plan running under this. If the open Internet fails, then Trade Desk fails.” (Mike, 36:17)
• Ari’s Take: TTD’s requests for standardization are attempts “to hug the Internet into some form of submission,” reducing chaos for buyers. [38:50]

7. Should Publishers Commoditize?

• Publisher Gripe: Standardization aids buyers—potentially turning supply into an undifferentiated “commodity.” (Chris, 39:49)
  • “Being standardized into a commodity… is the last thing I want as a publisher.”

8. Advice for Publishers

Mike O’Sullivan (43:40):

• “Publishers should talk to buyers and hear what the buyer has to say in terms of what they value. And if they say they value something, you should hold them accountable.” Chris Kane (45:07):
• “Apply as much pressure as possible to get clarity on how your inventory is presented on the buy side, and ask DSPs to circle back useful data.”

Notable Quotes & Memorable Moments

• “This thing has been around for two years… but now it seems consequential to publishers.”
  —Chris Kane, 12:32

• “On one Roku device, in a single day, 1.7 million bid requests… If you watched all those ads, it would take you until April 2027.”
  —Mike O’Sullivan, 18:09

• “Is it appropriate to tell publishers it’s their responsibility to create a fair and transparent auction? Sellers don’t want transparency, they want more revenue.”
  —Chris Kane, 18:28

• “The existence of widespread transaction ID would create a more fair… set of auctions. But I’m not sure it’s appropriate to tell publishers that’s their job.”
  —Chris Kane, 18:28

• “Of course publishers are scared of The Trade Desk. Anything that even comes within the neighborhood of dictating how they sell inventory triggers extreme reactions.”
  —Chris Kane, 33:59

• “We just want a clean auction. When advertisers leave the open internet because of poor performance, we all lose.”
  —Mike O’Sullivan, 31:52

Detailed Timeline & Timestamps

| Timestamp | Key Discussion | |-----------|----------------| | 02:32 | Ari defines TID and its context in OpenRTB; the TTD/Prebid controversy. | | 10:07 | Mike recounts his LinkedIn post igniting debate; why it popped up now. | | 13:54 | Chris outlines main publisher concerns (revenue and data leakage). | | 15:51 | Mike on signaling theory: “High-quality publishers...under-monetized.” | | 18:09 | Mike’s “1 Roku device, 1.7M bid requests” anecdote. | | 21:01 | Mike announces Prebid’s breaking change—TIDs now exchange-specific. | | 27:31 | Chris: “The choice was made for you by Prebid. It’s a real miss.” | | 33:59 | Chris: “Publishers are scared of The Trade Desk.” | | 36:17 | Mike: No secret plan, TTD’s incentives aligned with publishers’. | | 39:49 | Chris: Standardization risks turning publishers into commodities. | | 43:40 | Mike’s advice: “Talk to buyers, hold them accountable.” | | 45:07 | Chris: Push for visibility into how inventory is presented to buyers. |

Related "Refresh" News Highlights

How the TID/Prebid Situation Ties to Broader Trends

[48:38]: Digiday reports TTD’s labeling of some SSPs as "resellers" is leading to up to a 50% decrease in publisher payouts via reduced algorithmic value.

• Publishers’ preference for supply path opacity—the same root cause as resistance to TIDs.
• Trade Desk’s OpenPath as a preferred, more transparent supply option.

[51:30] TID’s Breaking Change:

• “It’s a breaking change, which means they broke it. So it no longer works.” (Ari)

Other Major News Discussed

• Pause Ads in CTV: Magnite now offering these programmatically; strong engagement data [54:32].
• AI Trends: Perplexity’s $42M publisher revenue pool, ZeroClick’s “AI ad network”, and Amazon blocking AI crawlers.
• Meta/Google/SSP industry moves, AI browser controversies, micropayments, and more.

Final Takeaways

• The Death of Transaction ID (for now): Prebid’s abrupt code change effectively neuters TID’s value, reversing hard-won gains in supply chain transparency.
• Publishers vs. Buy-Side Power: TID is a flashpoint in the enduring friction between publisher revenue strategies and buy-side demands for efficiency and transparency.
• Next Steps for Stakeholders: Publishers should proactively engage buyers to understand (and pressure them about) valuation signals; buyers must communicate their priorities clearly and fairly, being mindful of the trust deficit.

Recommended For

• Industry insiders wrestling with the implications of TID, Prebid changes, and programmatic transparency.
• Publishers/Brokers looking for practical strategies amid shifting standards and power dynamics.
• Advertisers/Buyers seeking to understand how inventory transparency (or its absence) shapes campaign efficiency.

Listen For

• A candid, “cutthroat” debate—often more a nuanced, inside-baseball discussion between two experts who broadly agree on the direction of progress, if not on path or incentives.
• Real-time “breaking news” as a technical standards decision upends the planned topic mid-episode.
• Illustrative metaphors (and battle scars) about the history and politics of ad tech standards.

Episode link and further resources available at marketecture.tv.