London-based advertising technology company pubX raised $5 million in a Series A round led by Chicago Ventures. The company announced the financing on October 6, 2026, alongside its acquisition of media quality and governance company Compliant. Financial terms of the acquisition were not disclosed.
Founded in 2020 by Andrew Mole and Alex Rosen, pubX develops agent-to-agent infrastructure for digital advertising. Mole serves as CEO, while Rosen is CTO. The company initially focused on technology for publishers before expanding to buyer-side products for brands and agencies.
pubX’s platform uses buyer and seller agents that can plan, negotiate, buy, sell and optimise advertising directly. Its infrastructure is built around the open Ad Context Protocol, or AdCP, which provides a framework for agent-to-agent advertising transactions.
Compliant develops media quality and governance technology, including data integrity and connected TV quality signals. The company will continue operating under the Compliant name as part of pubX, with CEO Jamie Barnard also taking the role of President, Global Demand Growth at pubX.
pubX said the Series A funding will support its expansion in the United States, development of its demand-side business for brands and agencies, further work on its buyer and seller agents, and integration of Compliant’s governance and media-quality signals into the platform.
