The auction question every AU retail media buyer should ask

On 31 August 2026 the US Federal Trade Commission and 22 state attorneys-general sued Amazon over the way it prices sponsored advertising. The complaint alleges that for more than seven years Amazon told advertisers its auction was second-price, meaning the winner pays one cent more than the next-highest bid, while in practice adding undisclosed "soft reserve" prices from 2019 that caused advertisers to pay their own full bid a growing share of the time: 30 to 40 per cent in 2021, about 70 per cent in 2022 and roughly 80 per cent by 2024. The FTC says more than one million brands and sellers were affected and describes the amounts as tens of billions of dollars. The release quotes internal Amazon descriptions of "an invented auction participant" and "a clever non-transparent way to charge first price". These are allegations in a complaint, untested in court. RetailDetail EU reports the FTC puts the alleged overcharge above US$20 billion since 2019; neither the FTC release nor that report carries a response from Amazon, and this piece does not characterise one.

Why it matters here

Australian retail media is now a real line item. Woolworths Group's F26 results report Cartology revenue up 7.8 per cent, with the second half at 11.3 per cent. Coles Group's 2026 Annual Report has Coles 360 income up 10 per cent on "new adserving and first party audience capabilities". Wesfarmers' 2026 results say OneReach broadened its advertiser base into utilities, financial services, automotive, government, travel and technology. As those networks add sponsored search and auctioned on-site placements, they inherit the exact question the FTC is asking Amazon: does the price you charge match the auction you describe?

The take

My view is that the mechanics of the auction are about to become a commercial term, not a technical footnote, and Australian networks should get ahead of that. Most retail media revenue here still comes from sold, not auctioned, inventory: screens, catalogues, sampling, sponsored content with a rate card. But sponsored product placements are the growth line everywhere, and they are auctioned by default because that is how the ad-tech platforms behind them work. The retailer often does not set the reserve-price logic; the platform does. That makes it very easy to describe your auction one way in a sales deck and run it another way in the software, without anyone intending to mislead.

The FTC case says intent is not the point. If the advertiser was told second-price and paid first-price, the gap is the harm. An Australian supplier who buys sponsored placements from a grocer is in an unusually weak position to argue, because the grocer is also their largest customer. That imbalance is exactly what the ACCC has spent the past few years examining in supermarkets, and it is not hard to imagine retail media pricing arriving on its agenda. I am not predicting a case; I am saying the question will be asked, and the honest answer should already be written down.

The fix is unglamorous. Publish the auction type. Publish whether reserve prices exist and how they are set. Give advertisers a report that shows what they bid and what they paid, per placement. If the network's platform vendor cannot produce that report, that is a vendor conversation to have this quarter, not after a complaint.

What to watch

Watch Amazon's response to the complaint and whether the case settles with disclosure commitments, because those commitments will become the de facto standard for auction transparency. Watch whether any Australian network volunteers its mechanics first. And if you buy retail media, put one question in your next negotiation: what auction do you run, and can you show me my clearing prices against my bids?