◆ E-COMMERCE · Marketing AI
You can buy ads inside ChatGPT. You cannot check whether your own ran.
The News
Similarweb (NYSE: SMWB) announced a new Ad Intelligence dataset, AI Ads, on August 17, 2026, covering ad placements inside ChatGPT, Google AI Mode and Google AI Overviews, worldwide and by market. In the figures released with it, 26% of ChatGPT responses already carry a sponsored ad, shown to users on the ChatGPT Free and Go tiers, and nearly 30% of ad-eligible Google AI Mode queries show ads. Over 40% of Google searches now trigger an AI Overview, which often include ads. Similarweb says the data is drawn from real user panel conversations rather than synthetic prompts, and notes that advertisers currently have no transparency layer for these surfaces, including for their own placements.
Chandni Melwani
Founder & Editor
Aug 21, 2026 · 2 MIN READ
Know More
- — The gap named: Meta runs the Ad Library, Google the Ads Transparency Center, and TikTok a Commercial Content Library covering Europe and the UK. ChatGPT, AI Mode and AI Overviews have no public equivalent.
- — The blind spot is first-party: Similarweb says most advertisers do not know whether their own ads are running in that context. Google's own help page confirms it, saying Google Ads currently does not offer segmented reporting when ads show within Search AI Overviews.
- — The trigger in ChatGPT: ads appear when intent exists and is clarified from the conversation, with placement decided by the combination of ad creative, copy and landing page.
- — The method: real user panel conversations rather than synthetic prompts. Similarweb says share of voice, ad categories and conversational intent are planned for later releases.
- — The caveat: Similarweb's figures are its own estimated metrics, produced by proprietary methodology and covered by its published accuracy disclaimer.
Sponsored placements now appear in 26% of ChatGPT responses on the Free and Go tiers, Similarweb said on Monday, and there is no library anywhere to look them up in. Meta’s Ad Library and Google’s Ads Transparency Center are searchable worldwide, TikTok’s Commercial Content Library covers Europe and the UK, and a marketer can open any of them and find their own campaign. The AI answer surfaces shipped the auction without the record.
Similarweb built the dataset because nobody else was counting, and the gap runs wider than ChatGPT: close to 30% of ad-eligible Google AI Mode queries carry a sponsored placement. Over 40% of Google searches now return an AI Overview, and those carry ads too.
The first-party blind spot is the operational problem. Similarweb says most advertisers cannot tell whether their own ads are appearing in Google’s AI answers, and Google’s own help page agrees: Google Ads does not offer segmented reporting when ads show inside Search AI Overviews. In ChatGPT, placement is decided when intent surfaces in the conversation, weighed against creative, copy and landing page, so a brand cannot even reason backwards from a keyword to where it showed up. That lands on merchants who have already done the work to be there: ChatGPT ads now ingest Google Shopping feeds across five markets, so the catalogue goes in and the reporting does not come back.
Advertisers do get aggregated views and clicks back from the platforms. What no one outside them can do is check the number, three months before peak season. The figures here are Similarweb’s own estimates, published by the company selling the fix, which is worth holding at arm’s length. The absence they describe is not in dispute.
So what: the visibility layer for AI advertising is being built by measurement vendors rather than the platforms, which means for now transparency is a subscription. Anyone spending here in Q4 should budget for it.
Related
Frequently Asked Questions
What is an ad transparency library and why does its absence matter?
It is a public, searchable record of the ads running on a platform. Meta and Google maintain one worldwide; TikTok's covers Europe and the UK, built for EU transparency rules. Advertisers use them to check their own creative is live and to see what competitors are running. Without one, a brand buying placement inside an AI answer has no independent way to confirm the ad served or what it appeared next to.
Does 26% mean a quarter of everything ChatGPT says is sponsored?
It refers to the share of responses that carry a sponsored ad on the Free and Go tiers, per Similarweb's panel-derived estimate. It is a measure of how many answers include a paid placement, not of how much of an answer is paid, and it does not describe paid tiers.
Who is publishing this number, and what do they sell?
Similarweb, a publicly listed digital measurement company, which is announcing the product that fills the visibility gap it is describing. The underlying figures are its own estimates rather than platform-reported data, so they are best read as directional until a platform publishes its own.
Sources
- Similarweb investor relations (August 17, 2026) — the AI Ads dataset, the 26% and 30% figures, and the missing-transparency-layer framing
- Google Ads Help — "Google Ads currently doesn't offer segmented reporting when ads show within Search AI Overviews"
- TikTok Commercial Content Library — the searchable ad record for the EEA, Switzerland and the UK
- Similarweb — AI Ads product page
- Similarweb — content disclaimer covering its estimated metrics
- OpenAI, "ChatGPT Ads expands across Europe" (August 18, 2026) — the advertiser-side expansion running alongside
Chandni Melwani
Chandni Melwani is the founder and editor of New in AI, covering AI agents, M&A, and enterprise adoption. She holds a Master's in Management of Artificial Intelligence from Queen's University and brings a practitioner's perspective from her work in Data and AI leadership.
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