Private marketplace (PMP)

A PMP is a deal ID riding in the bid request: the publisher names who may buy, and your DSP bids only where that ID appears. Amazon DSP runs two non-guaranteed PMP types — private auction, priced off a negotiated floor (priceType FLOOR_RATE), and preferred deal, a one-to-one fixed CPM (FIXED_CPM) where bidding above the fixed price still pays only the fixed price. Neither guarantees delivery. Below sits the open exchange; above sits programmatic guaranteed — fixed price, guaranteed volume, no auction. Amazon's PMP guide still describes private auction as a second-price auction paying a penny over the runner-up, but the clearing mechanic is the publisher's SSP's to set, and open-internet supply has been moving to first-price since 2019 — negotiate the floor and confirm the mechanic with the supply partner.

PMP failure rarely looks like failure — it looks like no supply, and the reflex is to raise the bid on a deal that never received a bid request. Open Deals in campaign manager and check whether requests are arriving; if none are, Amazon's instruction is to go back to the supply partner, and its pre-launch checklist names the usual causes — a floor price that does not match the SSP, a missing child seat ID, a preferred deal keyed in as a private auction. If requests arrive but you are not bidding, the No bid reasons column names the setting: frequency cap, viewability threshold, creative size, geo. Read dealType too — an Auction Package carries a deal ID, but Amazon files it as an open auction extension, not negotiated private supply.