Hidden Marketplace Revenue: How Marketplaces Earn Ad Revenue From Third-Party Sellers (2026)

Last updated: October 2026. Reviewed by Kunal Damgude, Growth and Product Marketing Manager.

Retailers and marketplaces earn ad revenue from third-party sellers by offering them paid placements on surfaces the marketplace already owns, such as search results, category pages and product pages, priced through an auction or a fixed fee and targeted with the marketplace's own first-party shopper data; Osmos runs that ad business for marketplaces through white-label onsite, offsite and in-store retail media. Sellers pay because visibility is the one lever they control on someone else's storefront, and the marketplace keeps a high margin because the inventory already exists.

Osmos is a white-label retail media operating system for retailers and marketplaces. Its modular apps for onsite, offsite and in-store ads sit over your existing stack, so you can break your monetisation ceiling faster without rebuilding it.

Advertiser-side returns are covered in our hub guide to retail media ROAS benchmarks by platform and ad format.

The Inventory Marketplaces Don't Realize They Own

The hidden revenue in a marketplace is inventory the marketplace already runs and currently prices at zero: search results, category listings, product grids, seller storefronts, homepage modules, recommendation widgets and order-confirmation pages. Each of them is commercial real estate in front of shoppers at the moment a purchase decision is forming.

Retail media is advertising that a retailer or marketplace runs on its own digital and physical surfaces, targeted with its first-party shopper data and measured against sales in its own transaction records. Osmos gives a marketplace that capability as modular apps: Osmos Onsite runs Product Ads, Display Ads, Product Display Ads, Video Ads, Custom Ads and Non-endemic Ads from one ad server, and the offsite and in-store channels are added when the marketplace is ready for them.

These surfaces exist because the marketplace runs commerce, and retail media works by putting a price on supply that is already there. Monetizing it adds no stock or fulfilment cost.

Boston Consulting Group projected that advertiser spend on retailers' owned channels would carry margins of 70% to 90%, while offsite media runs at 20% to 40% after media costs and agency fees (BCG, 2022). A marketplace's net margin on the goods themselves is a small fraction of that.

Osmos groups a marketplace's surfaces into three tiers by where the shopper is in the purchase:

• High-intent placements: search results, category pages and product grids, where the shopper has already typed or browsed toward a need.
• Mid-funnel touchpoints: homepage modules, recommendation carousels and seller storefronts, where discovery and new launches get attention.
• Post-purchase moments: order confirmation and order tracking pages, where repeat purchase and cross-category discovery happen.

Each one can carry paid placement without harming relevance when the ranking logic weighs the shopper's intent as well as the bid. Food delivery apps have already turned these surfaces into a revenue line, covered in our guide to food delivery platform monetization.

How Do Retailers Earn Ad Revenue From Third-Party Sellers?

A marketplace earns ad revenue from third-party sellers by charging them for prominence in its search results, category grids and product pages, through cost-per-click (CPC) auctions or fixed-fee placements, and Osmos is the white-label retail media operating system marketplaces use to run those auctions, placements and seller billing over their existing stack. That demand is already present on every marketplace: established sellers protect share and new sellers fight to break through, and both already spend to influence ranking: they optimize listings, discount aggressively or buy external traffic to send shoppers back to their own pages.

With a retail media layer, sellers bid openly for placement, and Osmos turns that informal competition into a priced, measurable auction the marketplace collects on. As PPC Land put it in its report on Walmart's Q2 fiscal 2027 results, "third-party sellers are the population from which sponsored product demand is drawn" (PPC Land, August 2026).

Osmos groups the ad revenue a marketplace earns from its sellers into five lines, usually switched on in this order:

1. Product Ads auctions. Sponsored listings in search, category and product pages, priced per click. This is the first line for almost every marketplace because the ad is built from the listing the seller already has. See Osmos Product Ads.
2. Onsite display and video. Display Ads, Product Display Ads and Video Ads for sellers and brand stores that want reach as well as clicks, usually priced per thousand impressions (CPM) or as a fixed sponsorship. Non-endemic Ads extend the same inventory to advertisers who do not list on the marketplace at all.
3. Custom formats at a premium. Custom Ads let the marketplace design bespoke formats for its own interface and price them above standard units to attract awareness budgets.
4. Offsite audience extension. Osmos Offsite activates the marketplace's first-party audiences on Google, Meta and TikTok, plus DV360 and Pubmatic for programmatic, and ties the result back to the sale. Our guide to which offsite channels to offer first covers the sequencing.
5. In-store media, where stores exist. Marketplaces with physical stores, pickup points or partner shops can add screens and physical placements as a fifth line.

That ad revenue adds to a marketplace's base revenue lines (seller commissions, fulfilment and logistics fees, subscriptions and payments), and it is funded by a wider pool than many marketplaces expect: established sellers defending their rank, new sellers buying a first audience, brands running official stores, and dropship suppliers who compete only on visibility.

Advertisers pay for those placements because the marketplace targets them with its own purchase and browsing signals, which no external network can match, across its inventory onsite and off. The mechanics are covered in our guide to first-party data activation for retail media targeting.

Flipkart's advertising income reached nearly Rs 5,000 crore in FY2024, up 51%, ahead of the Rs 3,734 crore Flipkart earned in marketplace fees that year (Storyboard18, October 2024).

How do public marketplaces report advertising revenue?

Public marketplaces report advertising revenue on different bases: eBay as dollar revenue and a share of GMV, Etsy inside the take rate, and Mercado Libre as a growth rate, so their figures are not comparable with one another.

Seller demand converts on the marketplace's own inventory when the marketplace has the data advantage described above and the operational scale to activate advertisers. Activating thousands of passive listers as advertisers takes automated onboarding and billing, and Osmos handles both with Brand Self-Serve, where advertisers set up, launch and optimize campaigns from one platform, and Wallets and Billing, which auto-debits wallet balances before they reach zero, extends credit lines to high-value advertisers and triggers rule-based incentives such as wallet credit for new advertisers, so seller activation scales without a headcount line per account.

How Can Marketplace Sellers Run Ads on a Retailer's Platform?

Marketplace sellers run ads on a retailer's platform through a self-serve campaign manager the marketplace provides, tied to their existing seller account and catalog, where they pick products, set a budget and bid, and see orders attributed back to their own SKUs. The retail media tools marketplace sellers use are therefore the retailer's tools, and it is the retailer's job to remove friction from each step.

Osmos lists the five points of a seller-ready setup in the order a seller meets them:

• An account tied to the catalog. The seller should not re-enter products, prices or images to advertise them.
• A campaign path that works without a call. A self-serve path lets the marketplace reach the majority of its seller base and keep account managers for its largest advertisers.
• A budget minimum a small seller can meet, with a prepaid wallet or credit line behind it.
• Reporting tied to the seller's own orders.
• Clear creative rules for the formats that need them.

Sellers usually start with Product Ads because they take no uploaded creative: the ad is assembled from the listing's image, title, price and rating, so the only lever a seller has is listing quality. Display Ads, sponsored brand units and Video Ads do take an uploaded asset, which is why brand stores and larger sellers usually add them second, and why the marketplace needs review rules before it opens them.

The best retail media ads for marketplace sellers are therefore Product Ads first and display second, and Osmos builds the seller experience around that order. Osmos Product Ads launch in one click, with products auto-selected from the catalog based on behavioral signals, and the Media Forecaster recalculates spend, impressions, orders, revenue and return on ad spend (ROAS) in real time as the seller changes settings, so the seller sees the likely result before committing budget. Order-level reporting by SKU, category and keyword closes the loop.

Which Retail Media Solutions Are Purpose-Built for Marketplaces?

Retail media built for marketplaces has to serve thousands of small advertisers who are also sellers, so it depends on self-serve onboarding, wallets and catalog-driven ads; Osmos is a white-label retail media operating system built for that mix, running a retailer's own catalog and its third-party sellers' catalogs from the same modular apps. Marketplacer, which often comes up in marketplace evaluations, is a marketplace platform whose retail media runs through partners, including Zitcha. For the selection decision itself, including self-serve versus managed models and what to ask each vendor, see our guide on how to choose a retail media platform for a marketplace.

How Should a Retailer Price and Package Retail Media Ad Inventory?

A retailer should price retail media ad inventory by matching a pricing model to the shopper's intent on each surface, then package those surfaces into tiers and bundles that map to what sellers and brands are trying to achieve.

High-intent surfaces such as search reward an auction, because demand for the top of a query is scarce and competition should set the clearing price. Awareness and launch surfaces such as the homepage suit a fixed sponsorship or CPM, because the advertiser is paying for a guaranteed moment in front of shoppers; on Osmos, a marketplace can price those as fixed sponsorships with exclusivity tiers that advertisers see at booking.

The Media Rating Council issued its final Digital Advertising Auction Transparency Standards on January 29, 2026, covering disclosure of auction type, winner determination, how bids convert to clearing prices and the use of reserve prices or floors, across channels that include retail media (Media Rating Council, January 2026). For a marketplace, that means documenting floor pricing and auction mechanics from launch. Osmos sets floors per slot with dynamic yield control: floor CPCs adjust to demand on every ad slot, and premium floors apply automatically on the most contested ones. The rate architecture itself, including where to set floors and how CPM, CPC and revenue-share models compare, is covered in our guide to retail media network monetization models.

Osmos Ad Packages bundle several formats into one bookable unit with a defined flight, price and delivery commitment, save event packages such as Black Friday or a festive sale as reusable templates, apply rule-based volume discounts and exclusivity tiers, and report promised against delivered for every package. Our guide to building retail media ad packages brands pay for walks through the package design.

Peak sales drive higher ad revenue when a marketplace aligns pricing to the heavier auction competition and prompts advertisers to top up their budgets. When a leading South African e-commerce marketplace maximised its annual peak-sale retail media revenue with Osmos, it reached R41.3M in ad revenue, its highest retail media month in 2025, with a 41% month-on-month revenue uplift. Osmos aligned pricing and bidding structures to the sharper auction competition of the sale, reported continuously on missed opportunities for prior-sale and low-budget advertisers, and sent real-time dashboard nudges when advertisers hit 100% of their daily budget. Those nudges alone drove R1.3M in incremental revenue directly, by preventing wallet exhaustion and prompting timely top-ups on peak days.

How Do You Monetize Marketplace Traffic With Product Ads?

Product Ads, the sponsored listings that appear inside search and category results, are the first format for almost every marketplace because they need no new creative and draw on demand sellers already have. The practical sequence is to open the format to sellers already spending on external channels, since they have budgets and performance expectations in place, then widen to the long tail once self-serve campaign creation exists. The same sequence answers how to monetize marketplace traffic with commerce media more broadly: start with the placements closest to purchase, then extend outward.

Ad load and auction design set the ceiling on Product Ads revenue. Ad load, meaning how many paid slots appear per results page, trades short-term revenue against the organic relevance shoppers came for. Auction design decides whether relevance is a ranking input or only price is, and that determines whether the format degrades the search experience over time. Osmos ranks Product Ads on intent and context signals alongside the bid, weighing category, price, cart, purchase and brand-affinity signals, and keeps same-brand products from appearing side by side.

Marketplaces that keep tuning ad load after launch keep both ad revenue and conversion intact. The signals to watch are conversion rate on results pages carrying paid slots compared with those that do not, and fill rate on each slot type; when fill is high and conversion holds, there is room to add load or raise floors.

How Do You Combine Marketplace Dropship and Retail Media for Maximum Revenue?

A marketplace combines dropship and retail media by using dropship to grow seller count and assortment with little inventory risk, then using retail media to monetize the extra competition for visibility that a wider seller field creates, so each lever adds to the return on the other.

Dropship moves inventory risk to the supplier and lets a marketplace add SKUs and sellers fast, but per-order economics are thin: TrueProfit's analysis of 1,200+ dropshipping stores in June 2026 puts a strong net profit margin at around 15% to 25% (TrueProfit, 2026). Retail media layered on the same traffic adds a parallel revenue line at the owned-channel margin range BCG describes, on attention the marketplace already commands.

More sellers competing for the same shopper means more bidders for the same placements, and dropship is one of the fastest ways to grow that seller count. Each new dropship seller is a candidate advertiser with a reason to bid: with no exclusive stock, visibility is the lever they can actually pull. As dropship adds sellers, it adds bidders to the ad auction that earns the higher margin.

The practical order is to grow assortment and seller count through dropship and marketplace onboarding first, then switch on retail media so the marketplace collects a price for the resulting competition. A denser seller base makes the auction liquid from the first day, so competition turns into clearing prices straight away. A modular, white-label ad layer co-exists with the systems already running the catalog, so the marketplace can do this without building ad tech in-house.

How Does Retail Media Create a Flywheel Effect for Marketplace Growth?

Retail media creates a flywheel because each turn of seller competition raises the revenue that funds the next turn: more sellers bid for visibility, auction pressure lifts the price of each placement, higher placement prices raise revenue per thousand impressions, the extra margin funds traffic and seller acquisition, and that brings in still more competing sellers. Once visibility carries a price, the marketplace is also a performance advertising destination, a first-party data activation layer and a closed-loop measurement environment.

Nick Hinsley, Chief Revenue Officer of Zitcha, described the loop in announcing the company's partnership with Marketplacer: "More sellers and broader product offerings drive traffic, which fuels ad revenue and product visibility." The public filings show the wheel turning: in the reporting table above, both eBay's first-party ad products and Mercado Libre's advertising grew faster than GMV in Q2 2026, a sign that advertising is compounding on top of commerce.

Osmos keeps the wheel turning on the marketplace side by lowering the cost of each new advertiser: one-click Product Ads launch, self-serve campaign management and automated wallet top-ups mean each additional seller-advertiser needs little or no manual work from the marketplace team. The flywheel starts turning as soon as enough sellers compete for the same placements to make the auction liquid, which takes a dense seller base and an activated ad layer.

Our analysis of the ROI and payback case for marketplace retail media works out what that compounding is worth in payback terms.

How Do Marketplaces Measure Retail Media Revenue?

A marketplace measures retail media revenue with a small set of ratios that tie ad income to the commerce underneath it: ad revenue as a share of GMV, advertising's contribution to take rate, revenue per active advertiser, the share of active sellers who advertise, fill rate and yield per placement, budget utilisation, and the attributed sales each advertiser sees in its own reporting. Osmos reporting breaks advertiser results down by SKU, category and keyword, and package reporting compares promised with delivered, so a marketplace can see which surfaces and which seller cohorts are carrying the revenue.

• Ad revenue as a share of GMV shows how deeply the marketplace monetizes its commerce, and it is the basis eBay uses in its quarterly results.
• Contribution to take rate shows advertising as part of what the marketplace keeps from each sale, the basis Etsy uses.
• Advertiser activation rate, the share of active sellers running at least one campaign, shows how far self-serve has reached into the long tail.
• Revenue per active advertiser separates growth from more advertisers from growth in spend per advertiser.
• Fill rate and yield per placement show whether inventory is priced well: a slot that is always full at the floor price is underpriced.
• Budget utilisation catches advertisers who run out of money before the sale ends, the gap the peak-sale nudges described above were built to close.
• Attributed and incremental sales are what advertisers see, and they decide whether budgets renew.

For attributed and incremental sales, IAB Europe's Commerce (incl. Retail) Media Measurement Standards V2.1 set out "a formal definition of incrementality, with approved methodologies specified" and "standardised definitions for gross and net sales", and a certification programme lets retailers and ad tech partners demonstrate audited compliance (IAB Europe, January 2026). Osmos Measurement runs incrementality through a configurable holdout that measures lift at view, add-to-cart and purchase; it is live in Early Access for onsite sponsored display, with an eight-week minimum window. For attribution models and windows, see our guide to retail media attribution and measurement.

Retail media network profitability is measured on margin. Because the inventory already exists, most of each additional dollar of ad revenue reaches operating profit, so a comparatively small ad business can move a marketplace's overall profitability far more than the same revenue from goods would. That is also how retail media contributes to store profitability for a retailer with physical stores. Our retail media business case guide sets out how to size that margin against GMV.

Who Else Owns Monetizable Traffic: Publishers, Marketplaces and Mid-Size Retailers?

Any business that owns commercial-intent traffic and a transaction record can run a commerce media network, which is why the category now includes publishers, marketplaces, delivery platforms, payments companies and regional retail chains alongside the national grocers that defined it. A commerce media network is an ad business that a company with shopper traffic or transaction data runs on its own surfaces and audiences; Osmos runs those networks for marketplaces, retailers, delivery platforms and fintech companies with the same onsite, offsite and in-store apps. For the full definition, see our explainer on what commerce media is. What differs between these businesses is where the demand comes from and how much of the stack each has to own.

How do publishers monetize with commerce media networks?

Publishers already own the audience and need to build a path to the transaction, a shift Digiday tracks across the publisher market, while retailers start with the transaction data and build the audience. Osmos sorts the publisher models by how much of the transaction the publisher owns, from none to all of it:

• Affiliate-plus: the publisher keeps its existing commerce content and layers paid placement and reporting on top of it.
• Retail media as a service: the publisher activates a retailer's first-party audiences against its own inventory and shares the revenue.
• Owned marketplace: the publisher runs its own transactional surface and monetizes it directly, at which point it faces the same seller-ad questions as any marketplace on this page.

Publishers add revenue streams and increase yield through commerce media because shopping-intent placements and audiences priced on sales outcomes typically earn more per impression than untargeted display. Implementation usually means integrating ad slots into existing pages and apps, connecting a commerce partner's product feed and sales data, and running both through one ad server. Closed-loop measurement is the constraint: without a transaction the publisher controls, attribution depends on a retail partner's data, which caps what advertisers will pay, so publishers that solve measurement first earn better rates than those that lead with reach.

How do commerce media networks generate revenue for businesses?

Commerce media networks generate revenue from onsite placements, offsite extension, in-store surfaces and insights products, and most start with onsite. Onsite placements, meaning sponsored listings and display on the business's own properties, are the largest and earliest. Offsite extension monetizes the audience beyond owned traffic, which lifts the ceiling once onsite inventory is saturated. In-store or physical surfaces apply wherever the business has them. Insights and clean-room collaboration products charge for measurement and planning, a route grocery retailers have pushed toward measurement standardisation. The mix shifts as a network matures, with onsite dominating early and offsite growing fastest once first-party audiences can be activated externally.

How can enterprise retailers use retail media to generate high-margin revenue?

Retail media draws board attention because of its margin structure. Thin product margins sit next to an ad line whose margins BCG estimated at several times those of the goods, so an enterprise retailer's ad business can contribute disproportionately to operating profit. The practical route is to start with the inventory that needs no new infrastructure (onsite search and category placements), prove closed-loop measurement on it, and reinvest the first revenue into offsite extension and in-store surfaces. Retailers should have a self-serve path running before they hire a managed-service team, so the ad revenue covers the headcount.

What is a retail ad network?

A retail ad network, or retail media network, is the advertising business built on one retailer's or marketplace's inventory, with that company's advertisers, audiences and reporting. Osmos provides that network as white-label software, so advertisers see the retailer's brand throughout.

Can a Regional Chain With 20 to 50 Stores Build a Retail Media Network?

Yes, a regional chain with 20 to 50 stores can build a retail media network, with a narrower design than a national one. The chain needs enough digital traffic or loyalty-identified shoppers to build segments of usable size, a supplier base that already spends on trade or shopper marketing, and a route to market that a small team can run.

The workable version concentrates on the categories where local share is strongest, activates suppliers already funding in-store promotion, and runs on self-serve plus a small commercial team. In stores, inventory is priced per store, per campaign or per day, tied to store count and duration, and targeted by store, day and hour: a dairy brand before noon, a soft-drink brand on weekend afternoons. That is how retailers monetize in-store traffic and maximize in-store retail media revenue without sensor networks.

Osmos In-store supports that model with a Retail Media Ad CMS, a Booking Calendar to plan, price and book inventory across screens and physical placements, In-Store Physical Media and Programmatic Demand, alongside the onsite and offsite apps, so the chain adds channels without adding a parallel operation for each. Our in-store retail media trends guide shows where larger grocers have taken the format.

Why This Revenue Stream Stays Hidden

Marketplaces can launch retail media without building a bespoke ad server. Modern retail media runs on modular, white-label software that co-exists with the existing stack, prices inventory the marketplace already owns, and is funded by sellers who are already paying for visibility elsewhere. Scale is the reason marketplaces most often give for waiting, and the flywheel begins once the auction is liquid, so a mid-market marketplace with a competitive seller base can build a meaningful revenue line well before it resembles Amazon. On seller demand, the filings in the reporting table show seller-funded advertising among the fastest-growing lines each marketplace reports. The hidden revenue business model is a new revenue stream for retail built from inventory, data and demand the marketplace already has.

Marketplaces that delay retail media lose ad revenue to competitors that launch it. For the build-versus-own question in more depth, see how marketplaces build their own ad platform. To see how the channels fit a specific marketplace, explore Osmos onsite retail media, Osmos offsite retail media and Osmos in-store retail media, or book a demo.

Frequently asked questions

How do retailers earn ad revenue from third-party sellers?

By charging sellers for paid placements in search, category and product pages, priced by auction or fixed fee, which Osmos runs for marketplaces as white-label retail media. In the accounts, that revenue can appear as its own line, as eBay reports it, or inside the take rate, as at Etsy, so check which basis a benchmark uses before comparing.

Do third-party sellers pay for ads out of their marketing budget or their margin?

Large sellers and brand stores usually fund ads from a marketing budget; small sellers fund them from margin, which makes them sensitive to any campaign that does not visibly pay back. That is why order-level reporting on the seller's own SKUs matters more on a marketplace than on a brand-funded network, and why Osmos lets a marketplace run wallet incentives, such as starter credit for new advertisers, to lower the cost of a first campaign.

Which commerce media providers deliver the highest publisher yield?

No independent ranking of providers by publisher or marketplace yield exists, because yield depends mainly on the media owner's inventory, pricing floors, packaging and advertiser demand. Compare platforms on how much control each gives the media owner over those levers; the platform-selection guide linked in the section on purpose-built solutions covers how to evaluate that.

What is the ROI of launching retail media on a marketplace?

Because the inventory already exists, the main costs are software, integration and the team that activates advertisers, while the revenue arrives at a high margin. The payback model, including how to estimate it for an enterprise retailer launching or running a marketplace, is covered in our marketplace retail media ROI guide.

How many sellers does a marketplace need before launching retail media?

There is no fixed threshold. What matters is whether several sellers compete for the same high-traffic queries and categories, because that competition is what makes an auction clear above its floor. A marketplace with a few hundred active sellers concentrated in contested categories can have a more liquid auction than one with thousands spread thinly.

Can a marketplace run ads for brands that do not list on it?

Yes. Non-endemic advertisers, such as financial services, travel or telecom brands that do not list products, can buy display and video placements on the same inventory. Osmos runs Non-endemic Ads in the same workflow as endemic ones, so the marketplace does not need a second ad stack to accept that demand.

How does a marketplace get started with retail media?

A marketplace gets started by auditing the surfaces shoppers already see and estimating their traffic, switching on Product Ads in search and category pages for the sellers already spending on external channels, opening self-serve with wallets so the long tail can follow, then adding display, packages and offsite once the auction is liquid. Osmos supports each step as a separate app, so a marketplace can start with one and add the rest over its existing stack, beginning at the Osmos platform.

Sources

1. eBay Inc., "eBay Inc. Reports Second Quarter 2026 Results," SEC 8-K Exhibit 99.1, August 5, 2026
2. Etsy, Inc., Q2 2026 Shareholder Letter, SEC 8-K, August 5, 2026
3. Mercado Libre, Q2 2026 results release (syndicated), 2026
4. PPC Land, "Walmart ad business gains 38% as Walmart Connect hits 43% in Q2," August 20, 2026
5. Storyboard18, "Flipkart's advertising income jumps 51% to Rs 5,000 crore in FY2024," October 29, 2024
6. Boston Consulting Group, "How Media Is Shaping Retail," 2022
7. Media Rating Council, Digital Advertising Auction Transparency Standards (Final), January 29, 2026
8. IAB Europe, Commerce (incl. Retail) Media Measurement Standards V2.1, January 2026
9. TrueProfit, "Dropshipping profit margin," 2026
10. Digiday, "What's in and out for publishers in 2026"
11. Grocery Dive, retail media standardization and data clean rooms
12. Marketplacer, "Zitcha and Marketplacer Partnership: Redefining Retail Media and Marketplaces," January 20, 2025 (marketplacer.com/press/zitcha-and-marketplacer-partnership/)
13. Osmos, "How a leading South African e-commerce marketplace maximised its annual peak-sale retail media revenue"