PMP (private marketplace)

A private marketplace is an invitation-only auction in which a seller offers inventory to selected buyers under deal terms carried in the OpenRTB Pmp object, typically with a higher floor and a first look, while still clearing each impression in real time.

OpenRTB models a PMP as a pmp object on the impression containing one or more deals and a private_auction flag: 1 restricts bids to the listed deals, 0 lets open-market bids compete alongside them (OpenRTB 2.6, section 3.2.11). The three common deal styles are the preferred deal (fixed price, non-guaranteed volume), the private auction (several invited buyers, floor, first price) and programmatic guaranteed (fixed price and guaranteed volume), which has its own entry.

PMPs grew because buyers wanted brand safety and sellers wanted price control without a sales call per campaign. They have since become the vehicle for curation, in which a third party packages inventory and data into a deal ID, and the Deals API v1.0 (4 December 2025) exists to synchronise those deals between SSPs and DSPs and to identify the curator (IAB Tech Lab, 4 December 2025). For a retail media network, the PMP is how offsite audiences are sold to brands through their existing DSP seats without the retailer running the auction itself.

Example: a publisher creates a private auction for its sports section with a $6.00 floor and invites four agency seats; the bid request carries private_auction: 1 and one deal with at: 1; the highest invited bid wins at its own price.

Related: deal ID, programmatic guaranteed, curation, ad exchange.

Source: IAB Tech Lab, OpenRTB 2.6, Pmp object; IAB Tech Lab, Deals API v1.0.

1. OpenRTB 2.6, section 3.2.11
2. IAB Tech Lab, 4 December 2025