How the Winner Is Chosen
An RTB price list in auction mode offers a slot to every demand partner it admits and compares what comes back. This page describes that comparison: which answers are eligible for it, what happens before price is looked at, and what the winner ends up paying.
It is written for the owner, admin and manager employees who decide which partners a price list admits and at what floor price, and for anyone reconciling a partner’s own reporting against the platform’s.
A price list in waterfall mode takes the first usable answer. See Waterfall mode.
Which answers reach the comparison
A partner’s answer has to survive several checks before it counts as a bid at all. An answer that fails one of them is dropped, and the partner is told why over the same channel used for loss notices.
| Reason sent back | What it means |
|---|---|
No bid amount |
No bid amount, or an amount of zero, from a partner not allowed to bid zero for this organization. |
Below the floor |
The bid is below the floor price the platform quoted for the creative’s length. |
Wrong creative length |
The creative is longer than the slot, or its length is not one the price list prices, or the price list requires an exact match and the creative does not have one. |
Campaign not targeted |
The campaign behind the creative is not targeted at this face. |
Creative does not fit |
No creative on the answer matches the face’s aspect ratio and resolution closely enough to be shown on it. |
Missing win notice URL |
An answer arrived without a win notice URL, which the platform requires. |
Unknown campaign |
The answer names a programmatic guaranteed campaign the platform cannot resolve. |
Only answers that pass all of these are compared. If none do, the request ends with an empty answer.
Programmatic guaranteed campaigns come first
A programmatic guaranteed campaign is a buy that was negotiated ahead of time and reserved a number of plays per hour on the face. It delivers through this same auction path, but it does not compete on price.
When at least one answer belongs to a programmatic guaranteed campaign that is inside its own schedule and still has plays left in its allowance for the current hour, that campaign takes the slot. No bid from any other partner is compared against it.
Which programmatic guaranteed campaign wins, when there is more than one, is decided by fairness. The platform prefers the campaign that is furthest overdue relative to its own spacing between plays, and a campaign that has not run yet on this face is treated as the most overdue of all.
A programmatic guaranteed winner is charged its reserved unit price for one play — the price agreed when the campaign was reserved. Nothing is computed from other partners' bids.
|
A confirmed automated guaranteed campaign is pushed into the content management system directly and does not pass through the auction. See Automated guaranteed delivery. |
The highest bid wins
Among the remaining answers, the winner is the one with the highest bid.
The comparison is on the bid amount as submitted, for the creative the partner offered.
If exactly one answer survives the checks above, it wins without any comparison.
Priority groups
An RTB price list in auction mode arranges its partners into priority groups, which collect partners that share a floor and a deal type. The groups are asked at the same time. If a partner must always be preferred, give it a price list of its own.
What the winner is charged
The auction is second price, unless the platform administrator has set first price for the winning partner, in which case the winner is charged its own bid. The winner is charged a clearing price derived from the runner-up’s bid and the floor price, expressed over the winner’s own creative length. Where there is no usable runner-up, the floor price is the basis.
The runner-up is the highest of the losing bids that does not exceed the winner’s, measured per second of creative. When the price list prices several creative lengths separately, only losing answers whose creative is the same length as the winner’s are considered; when the price list prices a single length, all losing answers are.
The clearing price is what the winning partner is told in its win notice, what the platform’s commission is calculated on, and what appears in reporting. The bid the partner originally submitted is recorded alongside it.