Amazon built its advertising business into a near-$70 billion annual revenue line by selling access to buyers who were already at the checkout. Now that business is the target. On August 31, the FTC and attorneys general from 22 states filed suit alleging Amazon secretly manipulated its ad auctions starting in late 2018, extracting more than $20 billion from advertisers who never knew the rules had changed. The question for investors is not whether this lawsuit is uncomfortable. It is how much it will cost, and whether the margin engine underneath it survives intact.
What the Complaint Actually Says
Amazon told more than 500,000 small and medium-sized businesses it ran a “second-price” auction, where the winning advertiser would pay just one cent more than the next-highest bid. Because businesses believed they would only ever pay slightly more than the runner-up, they had an incentive to bid high, trusting the system would keep their actual costs in check. But beginning in late 2018, the FTC alleges, Amazon made a “surreptitious” change without telling advertisers, adding a hidden surcharge it internally called a “soft reserve price” and using what the complaint calls an “invented auction participant” to push prices higher than real competition would have produced.
Internal Amazon documents cited in the complaint suggest employees discussed raising prices while hoping advertisers would not notice and decrease bids or ad spend. Amazon allegedly tested how much it could increase hidden charges without being detected by advertisers. The complaint also alleges that the one webpage that explicitly described Amazon Ads as a second-price auction was removed after Amazon learned of the FTC investigation in October 2024, and that the company did not disclose that removal to the FTC until August 26, 2026, five days before the complaint was filed.
Why the Ad Business Is the Margin Story
Amazon’s advertising services segment generated $68.6 billion in full-year 2025, growing 22.1% year over year. In Q2 2026 alone, advertising services rose to $19.8 billion, a 26% year-over-year increase. Amazon does not disclose a standalone operating margin for advertising, but it is widely described by analysts as a high-margin business within Amazon, often compared with AWS. This is arguably Amazon’s most profitable business per dollar of revenue. That is the segment now under federal scrutiny in this case.
The lawsuit is a major federal action against Amazon, filed by the FTC and 22 states in federal court.
The Prime Settlement as a Pricing Guide
The most useful data point for sizing this exposure is what Amazon already paid. The FTC secured a $2.5 billion settlement on September 25, 2025, alleging Amazon enrolled millions of consumers in Prime subscriptions without their consent and knowingly made it difficult for them to cancel. Under that order, Amazon was required to pay a $1 billion civil penalty and provide $1.5 billion in refunds. That case involved consumer harm spread across a subscription product. This one involves advertiser harm spread across a near-$70 billion revenue line, with the government alleging a $20 billion overcharge. Even if Amazon settles at a fraction of that figure, the exposure is materially larger than Prime.
Bull vs. Bear
The bull case rests on a practical reality: for many brands, Amazon is incredibly hard to walk away from. Sponsored Products connect to purchase intent that Google and Meta cannot replicate from their inventory. Advertisers who need to sell on Amazon’s marketplace will keep buying Amazon’s ad placements regardless of this lawsuit’s outcome.
The bear case is that the lawsuit directly targets advertiser trust in the auction system underpinning those Sponsored Products. Amazon called the FTC’s lawsuit “misguided” in a blog post, arguing the complaint “fundamentally misunderstands how advertisers operate.” That defense will face the internal documents the FTC has already quoted in the complaint. If the government can establish its shill-bidding theory at trial, any eventual payment will be shaped by the alleged damage figure, not Amazon’s willingness to negotiate down.
Bottom Line
Amazon shares fell about 3% following the filing. That is modest given the dollar figures in the complaint, which suggests the market is treating this as eventually settleable rather than structurally threatening. The Prime precedent gives Amazon a playbook: deny wrongdoing, pay the number, move on. But Prime was a consumer-facing product worth billions. The ad auction is the mechanism that generates nearly $70 billion a year. Watch Q3 2026 advertiser spending data and any signal of bid discipline softening. If advertisers start pulling back budgets because they no longer trust the auction, the margin story changes fast.
