An Amazon ad surcharge is the difference between the price Amazon's advertising auction produces and the higher price Amazon charges the winning advertiser. The word is Amazon's own, running through internal documents quoted in a 181-page complaint that the Federal Trade Commission and 22 state attorneys general filed against the company on August 31, 2026. In public, Amazon calls the same mechanism a soft reserve price, its estimate of what a placement is worth. Both name one object: a number applied on top of the auction result after bids are ranked and a winner chosen.

The term matters because of what it displaces. Amazon has told advertisers since at least 2014 that its Sponsored Ads clear through a generalized second price auction, or GSP, the model search advertising has used since the early 2000s, in which the winner pays roughly a penny more than the next ranked bid. A surcharge cuts that link. Price stops reflecting what a rival would pay and starts reflecting what the seller decides to charge.

How the two-stage price is built

Amazon sells three self-service formats against search results and product detail pages: Sponsored Products, Sponsored Brands and Sponsored Display. Sponsored Products is by far the largest, allocating slots at the top, middle and bottom of the search page on desktop and mobile. Advertisers bid on keywords, and Amazon ranks eligible ads by bid and by relevance signals including predicted click-through and conversion rates.

Pricing happens afterwards, in two stages according to internal documents cited in the complaint. Amazon computes the price the GSP auction would produce, known internally as the GSP CPC, then transforms that figure into the final cost per click by applying a soft reserve.

Two kinds of reserve operate here, and the distinction carries the dispute. A hard reserve is a conventional floor: a bid must clear it to enter the auction, and Amazon says it covers costs. A soft reserve is calculated after the winner is known. On Amazon's own account, a winning bid above both reserves pays the soft reserve, and a bid that clears the hard reserve but not the soft one still wins the slot and pays in full. Either way the bid caps the charge. "In no scenario does an advertiser pay more than their bid," the company wrote in its same-day response.

The engine behind the number is what Amazon internally calls eOPS Based Pricing, keyed to estimated ordered product sales, its forecast of the revenue a click will generate. It was tested in 2021 and became the primary method of setting Sponsored Products surcharges from 2022. The lever it pulls is return on ad spend, the sales an ad produces divided by its cost: a higher figure favours the buyer, a lower one the seller. The FTC alleges Amazon calibrated reserves to hold that return at a chosen level rather than let competition set it.

The metric the auction team used to track its own drift is the first price rate: the share of clicks priced at the advertiser's own bid rather than at the minimum needed to win. Internal reports cited by the FTC put it at 4% in late 2020, 30% to 40% in 2021, 70% in 2022, and roughly 80% by 2024, when Amazon also set the price on 70% of Sponsored Brands clicks and charged those winners their own bid half the time.

Automated bidding compounds this: dynamic bidding adjusts a bid by up to 100% in either direction, rule-based bidding by up to 500%, and placement modifiers by as much as 900% on premium slots. An advertiser using them cannot know which bid entered the auction, leaving the charged price unreconcilable against anything.

Where the practice came from

Amazon began running advertising auctions around 2012, according to the complaint, which cites an internal 2021 document recording that Sponsored Products ran GSP without reserves as of 2018. Amazon's account starts at 2006.

The company's explanation of what changed is that machine learning relevance models, tested from 2014 and fully deployed by 2019, shifted weight away from bid amount. Cheaper but more relevant ads won more often, and premium placements began clearing below what Amazon considered market value. Soft reserves closed that gap.

The complaint dates the first undisclosed reserves to Sponsored Brands in late 2018, during the Christmas period, with Sponsored Products following in mid-2019 and Display Ads by 2023, and records a different internal reason: dissatisfaction with what the auctions were returning. The team capped the share of auctions priced at the winning bid, then raised that ceiling repeatedly once experiments in 2019 and 2020 showed advertisers could not detect the change.

Why nobody could check

Reporting opacity is the structural condition that makes a surcharge possible. Amazon does not itemise invoices by click. Reporting aggregates at keyword level and mixes placements and devices, so an advertiser sees an average, never a cleared price beside a runner-up bid. Internal documents quoted in the filing call that reporting opaque.

The opacity carries commercial value, because the rational response to a first price auction is bid shading, lowering a bid to test how far above the competition it landed. In a genuine second price auction, shading is pointless. Amazon employees expected disclosure to trigger it, and a fall in revenue with it. Engineers estimated in January 2025 what a year of perfect shading would save advertisers. That figure is redacted, as are the average surcharge rates and the guardrails on reserves.

What the FTC alleges and what Amazon answers

The case, number 2:26-cv-03097 in the Western District of Washington, is a consumer protection action under Section 5(a) of the FTC Act and 22 state statutes, not an antitrust suit. It covers some 1.2 million United States advertising customers, more than 500,000 of them small and medium-size businesses, and the FTC puts the sum extracted above 20 billion dollars. The complaint compares the mechanism to shill bidding, citing William Vickrey's 1961 paper, which named the sealed-bid second price auction and warned of exactly this failure. The FTC's press release quotes an internal description of an "invented auction participant" used to lift prices, and the complaint has the head of Amazon Ads calling the second price a "proxy 2nd price that we calculate".

Amazon called the suit misguided and disputes the harm rather than the mechanism, arguing that reserve prices are ordinary industry practice. It states that average cost per click for Sponsored Products search ads was flat in inflation-adjusted terms from 2019 through 2024, that conversion rates rose more than 24% between 2021 and 2025, that roughly 92% of ads selected in 2024 were not the highest bid, and that the mean winning bid ranks about 128th by amount. Its headline number is 8 billion dollars, the sum it estimates advertisers saved from 2021 to 2025 because relevance outweighed bid.

The two sides measure against different baselines, and that is the analytical core of the case. Amazon compares its auction to a hypothetical one ranked purely by bid; the complaint compares the charged price to the GSP price the same auction had already computed. Both can be arithmetically correct. Only the second matches what Amazon's training materials described.

The filings also disagree on facts. Amazon's summary dates a 50% fall in average winning bids to 2019 through 2025 while the body of the same document says 2019 through 2024, and the complaint places Amazon's knowledge of the investigation in September 2024 in one paragraph and October 2024 in another.

Adjacent terms

Regulatory Advertising Fee is Amazon's disclosed pass-through of digital services taxes, applied by destination country and itemised on invoices. It reached Canadian-served ads in August 2024 and was unwound after Canada rescinded the tax in June 2025. It is visible by design, the contrast the FTC draws.

Fuel and logistics surcharge is a fulfilment charge, not an advertising one: a 3.5% version applied to FBA and related programmes from April 17, 2026, averaging about 17 cents per unit. Same sellers, none of the same systems.

Soft reserve is the generic auction concept, long present in exchange pricing and largely vestigial on the open web after the move to first price auctions in 2018 and 2019. Hard reserve is the ordinary floor, disclosed in effect because a bid below it never competes.

Recent developments

Public disclosure arrived late and in one place. Amazon added a reference to reserve pricing to a single Support Center page on October 30, 2025, a year after learning of the investigation, without defining the term. A March 2026 revision stated that the price charged may exceed the runner-up bid but never the authorised maximum. The FTC had opened parallel inquiries into Amazon and Google in September 2025; this complaint is the first to reach a court.

Comparable litigation runs against Google, where a federal court ordered disclosure of material ad auction changes in September 2025 and publisher suits from The Atlantic and Teads turn on the same gap between a declared auction and the one actually run. Standards work remains unsettled after Check My Ads Institute objected to the Media Rating Council draft and IAB Tech Lab published auction definitions for comment in January 2026.

The exposure is not confined to one company. Onsite sponsored formats across retail media inherited the second price model from search, and most competing networks were built against Amazon's version of it. Amazon reported advertising services revenue of 19.8 billion dollars in the second quarter of 2026, up 26%. It has also begun moving inventory off the auction, adding fixed-price top-of-search reservations for branded Sponsored Brands terms in October 2025.

Timeline

  • 1961: William Vickrey publishes Counterspeculation, Auctions, and Competitive Sealed Tenders, warning that sealed-bid second price auctions are open to shill bidding
  • 2006: Amazon first sells ads in its store, pricing clicks through a form of generalized second price auction, according to Amazon
  • Approximately 2012: Amazon begins running its advertising auctions, according to the complaint
  • At least 2014: Amazon begins representing that auction winners pay a penny more than the next highest bidder
  • 2014: Amazon starts testing machine learning relevance models
  • Late 2018: undisclosed soft reserve pricing begins in Sponsored Brands auctions during the Christmas period
  • Mid-2019: reserve prices extend to Sponsored Products
  • Late 2020: internal reports show a 4% first price rate for Sponsored Products
  • 2021: eOPS Based Pricing is tested; the first price rate reaches 30% to 40%
  • December 2021: a surcharge constraint is removed and cost-per-click spikes draw complaints from more than twenty advertisers and agencies
  • 2022: eOPS Based Pricing goes marketplace-wide in the United States; the first price rate reaches 70%
  • July 2023: surcharge limits are raised across the United States marketplace during Prime Day
  • 2023: reserve pricing extends to Display Ads
  • September or October 2024: Amazon learns of the FTC investigation
  • 2024: the first price rate reaches roughly 80%; Sponsored Brands winners pay their own bid half the time
  • January 2025: Amazon staff estimate annual advertiser savings from perfect bid shading; the figure is redacted
  • September 2025: the FTC opens consumer protection inquiries into Amazon and Google over search ad pricing disclosure
  • October 30, 2025: Amazon adds a first reference to reserve pricing to one Support Center page
  • March 2026: the Support Center text is updated to state that the charged price may exceed the runner-up bid
  • August 31, 2026: the FTC and 22 state attorneys general file Case 2:26-cv-03097; Amazon publishes its response the same day

Summary

Who. Amazon sets the surcharge; approximately 1.2 million United States advertising customers pay it, including more than 500,000 small and medium-size businesses. The Federal Trade Commission and the attorneys general of 22 jurisdictions are the plaintiffs challenging it.

What. The gap between the generalized second price auction result and the higher cost per click Amazon charges, produced by a soft reserve calculated after the winner is known and capped by the winning bid. Amazon describes the same mechanism as a market-value estimate and denies advertiser harm.

When. Late 2018 in Sponsored Brands, mid-2019 in Sponsored Products, 2023 in Display Ads, with the first price rate rising from 4% in late 2020 to roughly 80% by 2024. The complaint was filed on August 31, 2026.

Where. Sponsored Products, Sponsored Brands and Display Ads auctions on Amazon.com and its mobile app, with pricing experiments also documented in Germany, the United Kingdom, France, Italy and Spain. The case sits in the United States District Court for the Western District of Washington.

Why. A closed-loop platform is both auctioneer and seller, and controls the reporting buyers would need to verify a clearing price. That combination makes an undisclosed post-auction adjustment both possible and, on the FTC's account, extremely profitable, while a disclosed one would invite bid shading.