Brian O'Kelley
Co-founder and CEO, Apostra (formerly Scope3); co-founder of AppNexus
Brian O'Kelley co-founded AppNexus, the ad exchange AT&T bought in 2018, and now runs Apostra, the company he co-founded as Scope3 and renamed in September 2026. ADOTAT has covered his public fight with DoubleVerify and IAS over brand safety, his argument with Jeff Green over the open internet, and the agentic buying protocol his company backs, including what it can and cannot yet prove.
More coverage: Brand safetyAI advertisingAdtech
“Exist yes. Work yes. Active in production at scale - not yet.”
Brian O'Kelley, written answers to ADOTAT on agentic buying, Aug 11, 2026
The record: The most forthcoming operator put live agent-bought volume at $2,000 to $3,000 a day. The governance protocol stays experimental until its 4.0 release in early 2027. Read the story
ADOTAT reporting on Brian O'Kelley
5 stories, newest first- Brian O'Kelley vs. Jeff Green: The Referendum on Adtech's Soul
LinkedIn as ad tech's public square, and its funhouse mirror.
- Wildly Inconvenient and Loving It: Brian O'Kelley vs. the Brand Safety Industrial Complex
Why Brian O'Kelley thinks you're doing brand safety like it's 2007.
- Special Report: Brian O'Kelley Just Declared War on DoubleVerify and IAS
And he's not sending flowers.
Also mentioned in
13 stories- Thrad Calls It a $1 Million Fund. Its Own FAQ Says It Isn't One.
Monetization Fund II is advertiser spend routed through Thrad's own DSP. Koah raised $20.5 million, Thrad resells ChatGPT, and OpenAI just turned the ad into an agent.
- Thrad Sells Ads Inside AI Chats. Its CEO Says Ads to Agents Aren't Advertising.
Andrea Tortella on Claude's ad-free math problem, putting his own face in ChatGPT's ad slot, and a desert island with nobody famous on it.
- Wire & File: Everybody Announced A Transformation. The Trade Desk Reset The Options
IAB Europe forecast agentic scale and Apostra reported $1.2 million, while The Trade Desk's repricing proxy reset Jeff Green's options.
- IAB Tech Lab Blames Arrogant Bros for Bidstream Lies
The self-proclaimed steward of OpenRTB says the market ignores all of her fixes out of hubris. Forty minutes earlier she said "capitalism, baby." One of those is the real answer.
- Everyone Is Selling AI Media Buying. AdCP And IAB Tech Lab Say It Isn't Running Yet.
Both Brian O'Kelley and Shailley Singh answered on the record about what agentic buying can actually prove. Nothing either of them described is running at scale.
- Sunday Issue: I Coined "Ad Tech Mafia." I'm Not Sorry.
Two failed retirements, one newsletter that's just a fax machine with a Twitter account, and why the Show goes dark for two Mondays.
- Phylicia Koh Says Privacy Is a Lie and Anthropic Is Lying About Ads
The Play Ventures GP has the most detailed vision of agent-to-agent advertising I have heard from anyone, including the people writing the protocol.
- Sunday Issue: Apparently I Bullied a Billionaire
The site looks different. The standards are new. The reporting is exactly the same, which is the part that upset people.
- Randall Rothenberg Ran Ad Tech for 13 Years. He Just Said It Cannot Think.
Rothenberg went looking for a way to record his guitar. He came back with a description of who is going to own your industry.
- Special Report: The Ledger Wars & Who Owns Advertising's System of Record in the Age of AI
Bill Wise: "They're going to run into a wall, and that wall is Mediaocean."
- The Trade Desk & Jeff Green: A Covenant, an Auditor, and 48 Percent of the Vote
Jeff Green is finally worried. Here is everything he broke to get here.
- Commoditization 3.0: The Nicest Thing in Adtech Is About to Become the Worst
The agents are the sewage now.
- The ADOTAT Show: Adtech's Detroit Moment
Dennis Pekel named a tax nobody can price. Inside his head, and inside the kit to interrogate every vendor selling you "AI."
Stories link to the newsletter at new.adotat.com. Corrections and right-of-reply responses to pesach@adotat.com.
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