pubX raises $5m Series A led by Chicago Ventures and acquires Compliant
The advertising infrastructure company plans to expand in the US and develop buyer and seller agents on AdCP.
pubX announced a $5 million Series A led by Chicago Ventures on 6 October 2026, alongside its acquisition of media-quality and governance company Compliant.
Building an advertising market for agents
The London company develops agents that help advertisers and publishers plan, buy, sell and optimise media. The financing will support US expansion, products for brands and agencies, continued development of buyer and seller agents, and integration of Compliant’s signals.
Its infrastructure uses the open Ad Context Protocol, or AdCP, to let buyer and seller agents work directly. Clients set commercial rules and retain approval at important stages of the process.
Adding media quality and governance
Compliant will keep its name and operate within pubX under CEO Jamie Barnard. He will also become pubX’s president of global demand growth, leading its work with agencies and advertisers.
The acquisition’s terms were not disclosed. Its quality and governance technology will become part of the information used by pubX’s agents when considering advertising inventory.
Use of funds
Expand in the United States
Build demand-side products for brands and agencies
Develop AdCP buyer and seller agents
Integrate Compliant quality signals