At Prebid DEVCON Germany in Cologne this week, one slide got a lot of people talking. It described a world where Amazon and Google both bid into the same auction, and where the publisher, rather than GAM, picks the winner.

So what is Prebid Server proposing, why does the latest Google ruling make the idea far more realistic, and what could it mean for publishers?

What the session proposed

Today, most publishers run Prebid on their site, often alongside Prebid Server. Bids are gathered and passed to the ad server, which makes the final call. In practice, that usually means GAM gets the last look and the last say.

The session turned that model on its head. Instead of the ad server having the last look and the last say, you do all the decisioning in Prebid Server. So essentially, Prebid Server becomes the ad server.

In that world, publishers would no longer need GAM to choose the auction winner, and they could wave goodbye to Prebid line items and key-value pairs. Prebid Server would act as both the integration hub and the auction orchestrator, while the publisher (facilitated by Prebid) chooses and renders the winning ad.

Direct-sold campaigns still have a place. The publisher’s ad server could be queried via an API and, if it has a sponsorship or a high-CPM deal to offer, that demand simply enters the auction alongside everyone else.

The biggest takeaway is that everything becomes a bidder. Even the ad server becomes a bidder, competing on an equal level with every other demand source.

Why the idea is suddenly realistic

A year ago, this might have sounded like wishful thinking. Then, on 16th September, the court released the full remedies opinion in the US v. Google adtech case.

Google has been ordered to build API integrations connecting Prebid to both sides of GAM (its AdX exchange and its ad server), and those integrations must be functionally equivalent. AdX will also have to submit bids to rival publisher ad servers on the same terms as GAM’s own ad server. Importantly for those of us in Europe, the rules apply worldwide, and a technical monitor will oversee compliance for six years.

Amazon already integrates with Prebid, so the slide’s vision of Amazon and Google bidding side by side is a lot closer than it once was. It won’t happen overnight, though. Google has 12 to 15 months to connect these Prebid integrations.

What it could mean for publishers

For me, this is a publisher story first and foremost, because it’s the publisher who would run Prebid Server, and it’s the publisher who would benefit most.

The first benefit is a fairer auction. When every demand source bids at the same moment, under the same rules, it’s much easier for publishers to trust the outcome. The ruling also requires Google to share data on winning and losing bids, and to publish documentation explaining how GAM picks auction winners. Together, that should shed light on decisions that have long been hard to see.

The second benefit is simpler ad operations. Anyone who has built and maintained hundreds (or thousands) of Prebid line items in GAM will know how much time that eats up. 

Google has already tried to ease this with Header Bidding Trafficking, which lets publishers bring Prebid demand into GAM without setting up line items. However, it's only available on Google Ad Manager 360, it only supports web display, and GAM still makes the final decision. A Prebid-led auction would take line items and key-value pairs out of the equation altogether, freeing ad ops teams to focus on yield rather than set-up

There are caveats, of course. Some industry observers doubt the remedies will change publisher revenues much at all, because so much depends on publishers actually using the new integrations. We’d agree that nothing changes unless publishers seize the opportunity. But for those willing to put Prebid Server at the centre of their stack, the potential upside is significant.

What happens next

The timing is tight. Google now has a short window to set out how it will put the remedies into action, and the parties have until 2nd October to submit a jointly proposed final judgment. And from the discussion in Cologne, Prebid.org hopes to use this period to publish a specification for how an ad server API could work within a Prebid-led auction.

That would give Google a clear, industry-backed blueprint to respond to, whether it chooses to adopt it or put forward an alternative. Either way, the question of how Google fits into a Prebid-led auction is now firmly on the table.

Where this leaves us

The slide that got Cologne talking has moved a lot closer to reality. The session showed how Prebid Server could take over decisioning from the ad server, the Brinkema ruling has given that idea real momentum, publishers stand to gain a fairer and simpler auction, and the coming weeks will show how Google responds.

At Netric, we see this as the biggest shift in header bidding since Prebid itself arrived, and we’ll be following every step closely. If you’re a publisher wondering how a Prebid-led auction could work for your inventory, get in touch.