The history of advertising is a history of unmeasured waste. Most of that waste hides in plain sight — impressions nobody counted, catalogs nobody opened. The complaint against Amazon's advertising business alleges a rarer kind: waste priced into the invoice itself.
Bottom line first. This case is not about whether Amazon may set reserve prices. It is about whether Amazon disclosed the pricing rule advertisers were bidding against 19. And it remains allegations, not findings: as of September 4, 2026, no court had found Amazon liable, awarded relief, or quantified advertiser damages 18. Read everything below with that line in view.
What the Complaint Says the Auction Was
The Mechanism
The complaint covers three placements: Sponsored Products, Sponsored Brands, and Sponsored Display 15. These are the endcaps and shelf-talkers of Amazon's store — the spots a seller buys to stand in front of a shopper who arrived ready to pay.
The alleged mechanics are simple to state. Around 2018 or 2019, Amazon introduced a hidden minimum — a "soft" reserve — into these auctions 14. Per the complaint, the reserve applied whenever it exceeded the generalized second-price outcome, while holding the charge per click at or below the advertiser's own submitted bid 18. In the complainants' phrasing, it functioned as an "invented auction participant": a phantom bidder whose only job was to lift the final charge above what genuine competing bids would have produced 18.
A merchant will recognize the shape. The posted rule said second-price: pay less than your top bid. The register, allegedly, rang first-price: collect the top bid. Advertisers were never charged above their own cap; that is not the dispute. The dispute is the discount they were led to expect and did not receive.
The Scale
Reserve prices are ordinary in auctions. A reserve that applies most of the time is not an edge case. It is the pricing system.
The complaint puts the share of Sponsored Products charges set at the advertiser's own winning bid at roughly 80% in 2024, up from 30–40% in 2021 20. It names more than one million affected advertisers, including more than half a million small and medium-sized businesses 12. If those figures are substantiated, the allegations stop being auction theory and go straight to the economics of Amazon's ad business 13,15. Four charges in five set by a rule the bidder could not inspect is not a rounding error. It is a waste fraction built into the cost of admission.
The Internal Paper Trail
The cited documents matter more than the mechanics, because they speak to incentives.
According to the complaint, internal documents stated that advertisers assumed a generalized second-price auction and would not simply be charged their first price — and that, on that assumption, they bid more than they otherwise would 5. If authenticated and read as alleged, that single sentence connects opacity to revenue. The bid was set by a belief. The belief was false. The difference was the margin.
Other alleged communications called the surcharge "good for Amazon" at the "cost of advertisers" 20. Others reportedly warned that disclosure could cause irrevocable damage to advertiser trust, lower bids, and sharp revenue losses 5. That last document deserves framing and a nail. It concedes, in the complainants' telling, that opacity had a price — and that Amazon knew which side of the counter paid it.
One practical problem follows. Advertisers cannot independently audit auction logs, which limits their ability to validate any of this outside the litigation process 17. There is no receipt to inspect. Discovery and judicial assessment are, for now, the only audit worth the name.
Amazon's Answer
A fair ledger records both columns. Amazon's defense aims at the complaint's weakest joint: what advertisers actually knew, and what actually moved their bids.
Four points, as reported. Amazon calls the lawsuit misguided and says advertisers have received auction and pricing guidance through campaign-management tools 5,9,10. A bid, on Amazon's account, is a maximum, not a promised final price; advertisers never pay more than the cap they set 18. Bidding decisions are driven by campaign performance, not by technical descriptions of auction mechanics 18. And Amazon frames the soft reserve as price optimization — a correction for placements whose relevance-weighted auction results historically underpriced their value 3.
Amazon also reports that average winning bids fell 50% between 2019 and 2025. Two cautions. Those are Amazon's own figures, not independently established here 1. And a falling average, however welcome, does not establish what rule produced each charge. Averages settle totals. They do not settle methods.
The defense's strongest card may be the simplest: advertisers could observe their cost per click and their returns 19. On the reading of the case offered here, that is also where it will be decided — less on whether advertisers could see what they paid and what it earned, than on whether Amazon's descriptions created a materially misleading expectation about how those charges were set.
Known, Alleged, and Unproven
Keep the columns straight.
Known: this is a coalition action including the FTC and 22 state attorneys general 11, and it is a civil enforcement matter, not a criminal indictment 4. Known: Amazon contests the theory, and its arguments — bid caps, campaign outcomes, relevance weighting, disclosed tools — create a genuine factual dispute, not a settled finding 6.
Alleged, not proven: the 80% share, the invented participant, the internal statements, and the overbidding they supposedly produced. The theory of harm, as established at the top, is disclosure — misrepresentation and nondisclosure — not the existence of a floor price.
Where the Cost Actually Sits
Now the money, and the point most coverage will miss. The financial exposure is not primarily a fine.
The downside splits into three conditional buckets: monetary disgorgement or penalties; injunctions that would force auction-format changes; and the behavioral response of advertisers themselves 20. Rank them by durability. A payment is a line item, booked once. A remedy that changes mechanics or mandates fuller disclosure changes the machine itself — forced changes could permanently reduce future advertising monetization 2. Trust carries its own invoice: diminished trust could lead advertisers to reduce spending or seek refunds 16.
The reach is wider than the ads income statement. Amazon operates the auction while also running the retail and seller ecosystem that depends on those placements, and the complaint accordingly challenges the perceived integrity of a key revenue stream tied to that broader platform 7. That is the standing tension in retail-media network economics: the house runs the auction, writes the rules, and sells the floor space. Question the rules, and every placement on the floor is repriced in the buyer's mind.
The most durable downside is exactly that structural one. An adverse ruling could change auction mechanics or disclosure requirements, and thereby affect the advertising business well beyond any immediate damages award 8.
The Question That Remains
The question is not whether it works, but how you know it works. An advertiser could verify the clicks and the conversions. What no advertiser could verify — outside a courtroom — was the rule that set each charge.
My trade taught me one suspicion: waste hides wherever measurement stops. A store can survive a customer who distrusts one price tag. It does not survive customers who distrust the register. If the allegations hold, the surcharge was never the real cost; the mispriced assumption underneath every bid was. If they do not hold, Amazon still owes the market an answer to a simpler question. When a seller raises a bid on your shelf, what exactly is that bid a bid against?