As of October 2026, only a handful of companies publicly describe agent-to-agent trading venues built on IAB Tech Lab standards, and most are exchanges, supply-side platforms or media owners offering their own supply to buyer agents rather than two-sided marketplaces. In IAB Tech Lab's Agent Registry, BidMachine, The Nexus Engine, GumGum and VideoEV list sell-side agents that cite OpenDirect 2.1, the Deals API or AAMP, IAB Tech Lab's Agentic Advertising Management Protocols. IAB Tech Lab named Equativ and PubMatic as early supporters of the registry, and both list deal-management agents there. The public record holds far more seller agents than neutral marketplaces, so a buyer's first job is to work out which of the two it is dealing with.

TL;DR. An agentic advertising marketplace is a venue where agents acting for different buyers and different sellers find each other, agree terms and record the deal. An SSP's seller agent, a DSP's buyer agent and an agent SDK are each one part of that picture. IAB Tech Lab's published AAMP material describes no compliance certification, so every claim has to be checked against the registry listing, the code and the company's own statements. Before trading, a buyer should ask about standards and versions, deal types, the deal record, human approval and neutrality.

What counts as an agentic advertising marketplace?

An agentic advertising marketplace is a venue where software agents representing different buyers and different sellers discover each other, negotiate within mandates set by people, and record what they agreed in a form both sides can retrieve.

An SSP sells inventory for publishers. When an SSP or exchange runs a seller agent, that agent offers the operator's own supply to buyer agents: one sell-side door, however much inventory sits behind it. A DSP's buyer agent does the same job from the demand side. An agent SDK is code for building an agent; IAB Tech Lab's AAMP page describes its Buyer Agent SDK and Seller Agent SDK as open-source reference implementations, not trading venues.

The two-sided test sorts most claims. Does the venue admit agents for buyers and sellers it does not itself represent, and does it give both parties the same record of the deal? A seller agent can fail both halves and still be useful. It is simply not a marketplace.

Which companies say they trade with agents on IAB Tech Lab standards?

As of October 2026, the most specific public statements sit in IAB Tech Lab's Agent Registry at registry.iabtechlab.ai. Each company writes its own listing, and IAB Tech Lab reviews the validation information. Listings that cite IAB Tech Lab transaction standards include:

BidMachine lists an "agentic seller agent for the BidMachine ad exchange" that supports OpenDirect 2.1, the Deals API and MCP transport. The listing says buyers bid in its open RTB auction, with other deal types on its roadmap.
The Nexus Engine lists Kintsugi, a sell-side agent for its "server-side programmatic exchange" that supports private marketplace and programmatic guaranteed deals via OpenDirect 2.1 and AdCOM 1.0, over A2A.
GumGum describes its Seller Agent as an MCP interface aligned with IAB agentic standards, covering product discovery, campaign planning, and order and line-item creation.
VideoEV lists digital out-of-home inventory on electric vehicle charging stations, with "AAMP 2.0 yield-priced negotiation" and "OpenDirect 2.1 booking".

IAB Tech Lab named Equativ and PubMatic among the early supporters registered at the registry's launch. Both now list MCP servers in the SSP category. Equativ's listing says its server "turns an AI assistant into a working media planning and deal-management interface for Maestro"; PubMatic's covers programmatic actions "especially around deals and inventory". PubMatic calls AgenticOS, launched in January 2026, "the operating system for agent-to-agent advertising", and a February 2026 release with Chalice AI described a custom bidding agent developed within IAB Tech Lab's Agentic Real Time Framework (ARTF). Equativ's December 2025 Media Planning Agent release describes an open platform where customers can bring their own agents through protocols including ARTF and AdCP, the Ad Context Protocol from AgenticAdvertising.org. Neither company describes itself as an agentic marketplace built on AAMP.

Further upstream, HyperMindZ contributed the Deals Sync API MCP Server to AAMP 2.3, according to IAB Tech Lab. Its chief executive, Mano Pillai, said the aim was "to give agents a single, standards-based way to execute deals".

Where does Alkimi fit?

Alkimi is part of IAB Tech Lab's AAMP work and builds to the AAMP framework, which includes OpenProposal. It has also filed public comments and change requests on the OpenProposal v3.0 draft, visible in the OpenProposal issue tracker. It runs a neutral agentic advertising marketplace in which buy-side and sell-side agents agree deals on a shared DealSheet. The DealSheet is written at agreement, timestamped, held by both parties and retrievable by either side independently, and humans keep approval rights at the deal level. The marketplace is being built to be AdCP compatible.

How can a buyer verify who is building what?

Lists like the one above date quickly, so the method matters more than the names.

Start with the Agent Registry. Filter by category, such as SSP or ad exchange, read what each company says its agent does, and check the three verification marks: domain, GPP and endpoint. A missing mark is a question to ask, not a verdict.

Then read the code. IAB Tech Lab's AAMP hub on GitHub links each component repository. Commit histories show who has written code; issues show who has commented. During the OpenProposal public comment period, which IAB Tech Lab has extended to 10 November 2026, anyone with a GitHub account could file a comment, and an open comment is not accepted text. The repository's governance file still lists its working group as "TBD". Likewise, a connector to an SSP in the reference seller agent is not a statement by that SSP.

Finally, read the company's own releases and IAB Tech Lab's press releases, which name contributors and quote supporters. IAB Tech Lab's Agentic Task Force weighs in on AAMP requirements and sets the registry roadmap.

What should a buyer check before trading through an agentic marketplace?

Standards and versions. OpenDirect 2.1, Deals API 1.0 (finalised in February 2026) and the OpenProposal 3.0 draft, which its repository states is not a ratified standard, are different claims.
Deal types. According to IAB Tech Lab, AAMP's Deals API support covers programmatic guaranteed, preferred deals, private marketplaces, the open marketplace and linear GRPs. Ask which the venue supports today.
The deal record. According to IAB Tech Lab, the Deals API pushes pre-agreed terms one way and does not support proposals, revisions or negotiations. The OpenProposal draft defines timestamped buyer and seller assent records for the binding version. Ask who stores the agreed terms and whether the counterparty holds an identical copy.
Human approval. According to IAB Tech Lab, AAMP 2.3 added human approvals for spend outside value-based thresholds. Ask where the venue's own approval gates sit and who can override them.
Neutrality. Ask whose supply and whose demand the venue represents, and whether its operator also runs an agent that trades in it.

Take a hypothetical agency agent with a £50,000 programmatic guaranteed mandate that finds two venues citing OpenDirect 2.1. If one keeps the only copy of the booking, the agency's finance team will reconcile against the seller's records. The checklist surfaces that before any money moves.

Frequently asked questions

What is an agentic advertising marketplace?

A venue where agents representing different buyers and different sellers discover each other, negotiate within mandates set by people and record the agreed deal for both sides.

Is a seller agent in the Agent Registry the same as an agentic marketplace?

Not necessarily. A registry listing describes one agent and its operator. Whether that agent fronts a two-sided venue or a single company's supply is stated in the listing text and is worth checking directly.

Is there an AAMP-certified marketplace?

No. IAB Tech Lab's published AAMP material describes no compliance certification. The Agent Registry reviews validation information about who operates an agent, not whether it implements AAMP correctly.

Does Alkimi run an agentic advertising marketplace?

Yes. Alkimi runs a neutral agentic advertising marketplace and builds to IAB Tech Lab's AAMP framework. Agreed deals are recorded on a shared DealSheet held by both parties, with humans keeping approval rights at the deal level.