Online marketplaces increasingly sell advertising alongside their core service of connecting buyers and independent sellers, creating a separate cost for businesses that want their products to appear more prominently.
In a 2026 market study of Poland, Latvia and Lithuania, the Organisation for Economic Co-operation and Development describes how marketplaces combine product listings, payments and other services with sponsored placements and advertising analytics.
For sellers, the audience is attractive because shoppers may already be looking for a product. For the marketplace, advertising can generate revenue in addition to transaction commissions and other service charges.
Paying for visibility and paying to sell
Marketplaces generally arrange transactions between independent sellers and buyers. A seller may pay a percentage commission, a fixed transaction fee, a monthly charge or some combination of these. Charges differ by platform and service.
Advertising is a separate choice. A sponsored listing can give a product more prominent placement, while an ordinary, or organic, result appears through the platform’s ranking system without that particular advertising payment.
The OECD notes two common ways to charge for ads. Cost per click means the advertiser pays when someone clicks an ad. Cost per thousand impressions is a charge based on the number of times it is displayed. Neither measure alone tells a seller whether advertising produced a profitable additional order.
A seller spending $50 on ads that produce $200 in sales still has to account for product costs, platform commissions, fulfillment, returns and other expenses. Some buyers might also have purchased without seeing the ad. Comparing similar periods or running a controlled test can help a seller estimate the additional sales generated.
Our earlier article on how retail display ads can affect shopper expectations examined a separate simulated-store study. Its results should not be assumed to apply to every marketplace campaign.
Who controls what shoppers see?
Platforms can rank products using factors such as relevance, price and delivery time, the OECD says. Some also show a featured offer, often called a buy box, when multiple sellers offer the same product. The platform’s design and ranking rules can affect which seller a shopper sees first.
The OECD identifies a potential tension when a platform both organizes ordinary results and sells paid visibility. Sponsored results can introduce shoppers to products, but readers need to be able to recognize when placement is advertising.
In the United States, the Federal Trade Commission’s guidance on native advertising explains that advertising should be identifiable as advertising when its format might otherwise mislead consumers. Applicable rules and disclosure duties depend on the jurisdiction and the placement.
Compare the whole cost
A seller choosing between its own website and a marketplace must compare more than advertising rates. A marketplace can provide access to existing customers, payment infrastructure and, in some cases, storage or delivery. An independent store gives a business a different relationship with its customers but may require separate spending to attract traffic.
The OECD study examines marketplaces in three European countries and also explains broader platform business models. It does not establish that paid listings are necessary for every seller or quantify the return from a particular advertising campaign.
Before increasing a budget, businesses can compare total revenue after marketplace charges and product costs, check which placements are sponsored, and review how much of their sales depend on a single platform.
