PubX raises $5 million to build agentic AI infrastructure for ads

This move signals a shift toward disintermediation in the programmatic stack by replacing traditional middle-layer software with autonomous agents. By building on the Ad Context Protocol rather than legacy pipes, pubX aims to eliminate the 'hallucinations' and high token costs associated with bolting AI onto outdated infrastructure. For the streaming ecosystem, this could simplify open-web buying to match the ease of walled gardens while improving transparency in CTV inventory quality. Watch for whether the IAB Tech Lab’s competing ARTF framework gains similar adoption among major buy-side agencies in the coming year.

PubX is building its agent-to-agent infrastructure on the open Ad Context Protocol (AdCP), developed through AgenticAdvertising.org, a consortium of ad tech companies of which pubX is a founding member. The platform launched its buyer agents this year after initially operating on the sell side helping publishers price and optimize inventory, and now handles both sides of a transaction without routing through a DSP or SSP. The buyer agent queries publisher seller agents, analyzes their inventory and audiences, discards what does not meet the brief's criteria while explaining why, and executes the buy autonomously within client-set autonomy levels.

Compliant will retain its name and operate as a pubX company, with Jamie Barnard taking the role of President, Global Demand Growth. Barnard, who spent more than 15 years at Unilever including as general counsel for global marketing, media and ecommerce, co-founded Compliant to deliver Data Integrity and CTV Quality Indexes used by global advertisers to measure media quality across the supply chain. The Series A funding led by Chicago Ventures will support pubX's US expansion, build-out of its demand-side business serving brands and agencies, and integration of Compliant's governance signals across the platform.

PubX positions itself at what it calls the intersection of AI and programmatic advertising, having launched just last month as a platform enabling independent AI agents to plan, buy, sell and optimize advertising on behalf of advertisers and publishers. The company's premise is that no one hands their media budget to a system they do not trust, so governance checks, reasoned and auditable decisions, and Compliant's quality signals are embedded in every transaction. As trust is earned through campaign performance, the level of agent autonomy grows, creating a graduated path from human-approved plans to fully autonomous execution.