GAM Demand Mediation

Serve Google Ad Manager demand for display ads.

GAM Demand Mediation enables marketplaces to earn incremental revenue from banner impressions that would otherwise go unfilled, without changing the existing Topsort setup.

For existing banner ad slots, GAM demand can be enabled by the Topsort account team. If Topsort returns demand, the marketplace renders the Topsort banner. If Topsort does not return a banner, the auction response includes a tag that requests a display ad from GAM. If GAM returns an ad, it is rendered in the same dimensions as the configured banner slot, for example, a 300 × 200 homepage placement.

GAM Demand Mediation can also be used by marketplaces that are not onboarded to Topsort banner ads. In this configuration, Topsort returns the GAM tag for enabled placements rather than a Topsort banner.

Benefits

• Monetize unsold inventory: Marketplaces can generate revenue from banner ad slots even when there is no Topsort demand.
• Flexible demand sources: GAM placements can be configured to access either the Open Auction for non-endemic demand or private marketplace deals for selected advertisers.

Availability

GAM Demand Mediation is available to Topsort marketplaces worldwide, pending Google approval.

Demand sources

Endemic brands

Google can work with retailers to bring existing endemic brands that are not yet onboarded to Topsort, or are not ready to onboard to Topsort, onto GAM instead. GAM demand can then be used to fill banner placements across the retailer.

Brands or their agencies buy this inventory through a demand-side platform (DSP), such as Google Display & Video 360 (DV360). A DSP is a platform advertisers and agencies use to buy advertising inventory programmatically across publishers.

Campaigns can be transacted through either a Preferred Deal or a Private Auction:

• A Preferred Deal is a non-guaranteed agreement between the retailer and a specific buyer at a fixed CPM. The buyer receives preferred access to eligible impressions at that price but is not required to purchase every available impression. For Preferred Deals, the brand or its agency can initiate an RFP (request for proposal) from its buying platform. An RFP starts the negotiation process between the buyer and publisher for the deal.
• A Private Auction is a non-guaranteed auction in which the retailer selects the buyers allowed to participate and sets a minimum CPM floor. Invited buyers bid against one another, and the auction determines the winning price. The retailer creates the deal in GAM, and the invited brand or agency accepts and bids on the deal through its DSP.

In either case, the retailer and brand align on the campaign details, including creative requirements, campaign dates, expected spend or delivery goals where applicable, destination URL, and the fixed CPM or auction floor. The retailer can require the destination URL to link back to its site. Topsort then configures the corresponding deal in GAM, and the brand buys against it through its DSP.

Non-endemic brands

GAM’s Open Auction provides access to demand from the broader open web. This is generally best suited to placements where ads may link users away from the marketplace, such as post-checkout placements.

The marketplace sets pricing rules, including CPM floors or target CPMs. Eligible buyers bid in real time, and the auction determines the winner and clearing price.

Protections

For endemic brands, Preferred Deals or Private Auctions can be used. These options allow the retailer to control which buyers are eligible to access the inventory.

For non-endemic ad slots, the Open Auction can be used with two primary controls:

• Protections: The retailer can configure GAM exclusions and filters to prevent unwanted advertiser categories or other unsuitable demand from appearing.
• Page context and relevance: Non-endemic demand can be enabled only for placements where it is appropriate, for example, post-checkout rather than pre-checkout. Relevant contextual signals about the page and placement can also be passed to Google to help inform ad selection.

Separately, GAM controls can be used to restrict advertiser categories or specific advertisers. Google also uses automated processes to screen creatives.

Payments

For demand transacted through GAM, Google pays Topsort the applicable advertising revenue after its fees, and Topsort then pays the retailer its share.

Reporting

Topsort will provide the retailer with a dashboard covering their GAM performance, including metrics such as impressions, clicks, revenue, and fill rate. Reporting can also be exported and shared with endemic brands where applicable.

Onboarding process

Marketplaces interested in GAM Demand Mediation should contact their Topsort account team.

A typical integration requires only a few hours of marketplace engineering time and can generally be completed during a single working session with a Topsort integration engineer.

1. Create a GAM account

   Create a GAM account if one is not already available.

   The retailer must have its own GAM account to establish the MCM Manage Inventory relationship with Topsort.

2. Align on pilot scope

   Select two to three banner ad slots for the initial pilot and agree on the applicable content moderation policies.

3. Set up the GAM MCM connection

   Link the Topsort and retailer accounts using GAM’s Multiple Customer Management (MCM) Manage Inventory model. Under Manage Inventory, the retailer delegates the relevant ad inventory to Topsort for monetization. The inventory, demand configuration, and reporting are managed through Topsort’s GAM network, while the retailer retains its own GAM account.

   The retailer adds the required entries to its ads.txt file. Topsort handles any required sellers.json configuration on the Topsort side.

4. Implement the passback flow

   Add a small code snippet to each enabled banner slot so that the placement can render either a Topsort ad or a GAM ad.

5. Test the integration

   Topsort validates the integration before launch.

Example response

When no Topsort demand is available for a banner slot enabled for GAM Demand Mediation, the auction endpoint returns a GAM snippet in the winner’s asset field. The marketplace renders this snippet to display the GAM banner.

{
  "results": [
    {
      "resultType": "banners",
      "winners": [
        {
          "asset": [
            {
              "content": "{\"type\": \"gam_snippet\", \"content\": \"<div id=\\\"gam-ad\\\"><script>googletag.cmd.push(function() { googletag.display(\\\"div-gpt-ad-12345\\\"); });</script></div>\"}"
            }
          ],
          "type": "url",
          "id": "https://www.example.com",
          "resolvedBidId": "PHRSCwoQBpvFL1sveOSZBCyVii_LCRIQAAAAAAAAAAAAAAAAAAAAABoQAAAAAAAAAAAAAAAAAAAAACIbChdodHRwczovL3d3dy5leGFtcGxlLmNvbRAFUIDQzO7O7_H__wFyEAAAAAAAAAAAAAAAAAAAAAA",
          "rank": 1
        }
      ],
      "error": false
    }
  ]
}

Each entry in the asset array contains a content field with a JSON string of type gam_snippet. The marketplace parses this content and renders the embedded HTML/JavaScript to display the GAM banner.

Passback flow

The only marketplace-side development required is a small code snippet in each banner slot enabled for GAM demand. If the response contains a GAM passback tag, the page renders the GAM ad. Otherwise, it renders the standard Topsort ad.

// response is response from Topsort auction endpoint
const { results } = await response.json();

const passback = results?.[0]?.winners?.[0]?.metadata?.passbacktag;

if (passback) {
  const iframe = document.createElement("iframe");
  document.getElementById("banner-slot-3")?.appendChild(iframe);

  iframe.contentDocument.write(passback);
  iframe.contentDocument.close();
} else {
  // render normal Topsort ad
}

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