Amazon’s Ad Auction Is Now a Trust Problem
Matthew Leo · Published September 5, 2026 · Business & Policy
Amazon’s advertising auction is now the subject of a major U.S. lawsuit, but the most useful lesson for sellers is already clear: a bid ceiling is not a pricing explanation.
On August 31, 2026, the U.S. Federal Trade Commission and 22 states sued Amazon. The complaint alleges that Amazon told advertisers its sponsored listings used a generalized second-price auction while quietly adding reserve prices that could push the winner closer to its maximum bid. Amazon rejects the accusation and says its system has delivered better results at lower winning bids.
These are allegations, not findings. A court will have to decide whether Amazon’s descriptions were deceptive and whether advertisers were harmed. In the meantime, brands buying Sponsored Products, Sponsored Brands or Sponsored Display ads should stop treating the auction label as a substitute for independent measurement.
What the FTC says Amazon changed
In a conventional second-price auction, the winner generally pays only enough to beat the next-ranked bidder. That structure can encourage advertisers to bid closer to what a click is actually worth to them.
The FTC says Amazon added a “soft reserve price” beginning in 2019 without adequately telling advertisers. According to the complaint, this reserve could act like an invented competing bid and raise the price above what advertiser competition alone would have produced.
The agency alleges the system generated tens of billions of dollars and affected roughly 1.2 million advertising customers. It also says Sponsored Products advertisers paid their full bid about 80 per cent of the time in 2024, up from 30 to 40 per cent in 2021.
Those figures come from the regulator’s complaint. They have not been proven at trial.
Amazon says relevance changed the economics
Amazon’s response is that the FTC misunderstands an auction that ranks ads using both bids and predicted relevance. The company says a higher bidder often loses to a more relevant product and that reserve prices help value premium placements.
Amazon says the average winning bid for Sponsored Products search ads fell 50 per cent from 2019 to 2024, while the inflation-adjusted average cost per click stayed flat. It also estimates that prioritizing relevance saved advertisers more than US$8 billion from 2021 through 2025. Those are Amazon’s own figures and estimates, not independent findings.
The disagreement is therefore larger than whether a reserve existed. It is about what advertisers were told, what they reasonably understood, and which counterfactual should be used to calculate harm.
What advertisers can check without waiting for court
- Separate bid changes from performance changes. Track cost per click, conversion rate, contribution margin and return on ad spend at the search-term level.
- Run controlled bid tests. Reduce bids on a defined group of terms and compare the change in placement, sales and profit with a stable control group.
- Measure incrementality. A sale credited to an ad is not necessarily a sale caused by the ad, especially for branded searches.
- Keep raw exports. Preserve campaign, placement and search-term data so a later methodology change does not erase the old baseline.
- Watch total retail cost. Advertising fees, referral fees, fulfilment charges and promotions all compete for the same product margin.
Canadian sellers are not plaintiffs merely because they advertise on Amazon, and the U.S. case does not automatically create a Canadian refund. Its practical relevance crosses the border because Amazon’s retail-ad platform is used by brands selling to Canadians and because opaque auction costs can influence which products get visibility.
The consumer-price claim deserves caution. The FTC argues that higher advertising costs can be passed through to shoppers. Amazon says the complaint does not substantiate that pass-through. Neither position proves what happened to the price of a particular product.
The durable issue is platform accountability
Retail-media platforms operate the marketplace, sell the ad space, rank the listings and report the results. That concentration makes clear rules and auditable outcomes unusually important. Mapletechie’s analysis of Apple’s tracking prompt as competition infrastructure raised a similar concern: a platform’s technical design can shape the market while looking like neutral plumbing.
Advertisers do not need to decide the lawsuit today. They do need to know the highest price they will pay, the result that price produces and whether the platform’s explanation matches the bill. If those three things cannot be reconciled, the campaign has a trust problem before it has a legal one.
Tags: Analysis, Amazon, advertising, competition, e-commerce