The Maze: Retail media has a seductive growth story: find a retailer with lots of sales and little advertising, then monetize the gap. The US comparison breaks that shortcut. Retailers converting only 1-2% of gross merchandise value into media revenue do not automatically grow faster. Amazon already converts almost one in ten GMV dollars into ads, owns the largest revenue base by far, and is still forecast to compound at 16.2% through 2028. Headroom is not a strategy. Demand is.
Low monetization does not create its own buyers. Macy's, eBay and Kroger sit around 1-2% media revenue versus GMV, yet their forecast growth ranges from roughly 10.8% to 15.6%. Etsy converts about 4% but grows only 10.1%. The US comparison shows no simple relationship between today's ratio and tomorrow's growth. Spare capacity matters only when advertisers can buy it, measure it and see enough sales impact to bid again.
Amazon is not hitting a ceiling. It keeps moving it. The company pairs the highest monetization ratio with the biggest ad-revenue base and the third-fastest named growth rate. That combination changes the economics. A 16.2% rate on Amazon's scale creates far more incremental dollars than a similar rate at a smaller network. Onsite sponsored search is only one layer. Seller-funded auctions, the demand-side platform, video, connected TV and off-site inventory expand what counts as sellable media. What looks like saturation from the GMV ratio can still be early in the inventory stack.
Walmart shows what credible headroom looks like. Its ratio sits a little above 2%, but its 22.3% CAGR is the fastest in the set. The difference is not unused space alone. Walmart is connecting buying, member data, store transactions, off-site reach and measurement across Walmart Connect and Sam's Club Connect. The retailer has scale, high shopping frequency and enough advertiser demand to turn new tools into auction pressure. Capacity plus infrastructure creates growth; capacity without demand stays empty.
The operating model predicts more than the ratio. Marketplaces can recruit thousands of third-party sellers who spend their own money through self-serve auctions and chase return on ad spend. First-party retailers often negotiate with a smaller set of large brands and annual trade-marketing budgets. Those are different engines. Retailers also need real-time reporting, closed-loop attribution and standardized measurement—the capability stack advertisers now expect. The better questions are seller density, traffic quality, auction competition and the ability to add off-site inventory without losing measurement.
Why it matters: Retailers should stop benchmarking retail-media potential with one ratio. GMV is feedstock, not a guarantee. The networks that compound combine purchase intent, advertiser density, self-serve access, credible measurement and more places to sell ads. That is why Amazon can look over-monetized and still grow fast, while a retailer at 1% can remain stuck. The monetization gap is an opportunity only after the demand engine exists.
