PubX raises $5M and buys a governance startup, betting the agentic sell side needs trust

PubX, the UK-based agentic ad startup founded in 2020, has raised $5 million and acquired Compliant, a media quality and governance startup co-founded by former Unilever general counsel Jamie Barnard. CEO and co-founder Andrew Mole's thesis is that agentic ad tech hallucinates not because of the language model but because it queries demand-side platforms that were never built to talk to an agent; so he built one that is. PubX started on the sell side helping publishers price and optimise inventory, then launched buyer agents this year so it handles both sides of a transaction. The Compliant purchase is the tell: for a brand to hand an agent its budget, it needs an audit trail, and governance is the thing being bought first.

The crux

An agent that buys and sells on the same platform is a structural conflict of interest, and PubX is buying governance to be trusted across both sides rather than to resolve the conflict.

Sell-side read

The sell-side question with any agentic platform is who it optimises for when it sits on both sides of your auction. Ask for the audit rights and the fee disclosure before the pilot; governance acquisitions are a signal that a clean story is still being assembled.

Watch

whether PubX's dual-sided model wins publisher pilots without a firewalled buying and selling split, the term every unified-platform pitch now has to answer.