TL;DR
- Semrush's AI Visibility Index, released 13 October 2026, found fewer than half of the top 100 brands AI answers mention are also top 100 cited domains, in every month and both markets.
- In July 2026 Tesco was ChatGPT's 25th most-cited UK domain and Asda 606th, although both ranked in ChatGPT's top 10 for brand mentions.
- ChatGPT showed the lowest mention-to-citation overlap: 28.7 to 32.3 of 100 in the UK and 32.8 to 35.8 in the US, January to July 2026.
- Any two AI platforms shared 63 to 70 of their top 100 brands in the UK versus 70 to 78 in the US, so results differ by market.
- The study has no Thai data, excludes Claude, Perplexity and Copilot, and comes from Semrush, which sells AI visibility tools.
Semrush, which has been an Adobe company since April 2026, released the H2 2026 edition of its AI Visibility Index on 13 October 2026 at its Spotlight London event, and the headline finding is that fewer than half of the brands AI answers mention most often are also among the sites those answers cite most. The study covers January to July 2026, adds a UK benchmark next to the US for the first time, and tracks ChatGPT, Gemini, Google AI Mode and Google AI Overviews. Its sharpest example: in July, Tesco was ChatGPT's 25th most-cited UK domain while Asda was 606th, even though both sat in ChatGPT's top 10 for brand mentions. Semrush sells AI visibility and GEO tools, so this is vendor research, and it contains no data on Thailand.
What Semrush measured in the H2 2026 AI Visibility Index
According to the Semrush press release dated 13 October 2026, the index is built from seven monthly measurements between January and July 2026. Each month, ChatGPT, Gemini and Google AI Mode were run against a fixed pool of 2.5 million UK prompts and 25 million US prompts, built from Semrush search data. Google AI Overviews was measured from a separate and larger collection based on real search keywords rather than prompts.
The trade publication PPC Land, which read the full 57-page report, adds detail the release leaves out. The AI Overviews keyword bases ran to about 4.35 to 4.80 million a month in the UK and 48.34 to 54.60 million in the US. For each platform, market and month, Semrush exported up to 10,000 mentioned brand domains and 10,000 cited source domains, then sorted them into 22 industry categories. The categories describe the domain, not the question that was asked.
Two definitions matter for everything that follows. A "mention" is a brand named in the answer text. A "citation" is a domain listed as a source for the answer. Per PPC Land's reading of the report, Semrush says neither one implies a recommendation, trust or editorial approval. They are counts of how often something recurs.
Mentions and citations are different measures
The core result of the Semrush index is that being named by an AI answer and being cited as a source by it are two separate outcomes. Averaged across 22 categories and four platforms, fewer than half of the top 100 mentioned brands also appeared among the top 100 cited domains, in every month and in both markets. Semrush gives the UK monthly overlap as 36.7 to 45.3 domains out of 100. PPC Land reports the US range as 41.4 to 47.4.
ChatGPT showed the weakest link between the two. According to PPC Land's summary of the report, ChatGPT's UK overlap ranged from 28.7 to 32.3 out of 100, and its US overlap from 32.8 to 35.8, below half in all seven months in both markets. Gemini's UK overlap was 33.4 to 36.9. Google AI Mode fell below half in five of seven months in each market, and AI Overviews in four of seven UK months and two of seven US months.
For a brand team the practical reading is simple. A dashboard that only counts how often your name appears in AI answers tells you nothing reliable about whether your own pages are being used as sources, and the reverse is also true. The two need to be tracked as separate numbers.
Tesco, Asda and Ford: the examples Semrush chose
Semrush used two UK supermarkets to show the gap. Both Tesco and Asda were in the top 100 mentions on all four platforms in every month of the study. Yet in July 2026, Tesco ranked 25th among ChatGPT's most-cited UK domains and Asda ranked 606th. On Gemini the same two ranked 29th and 60th. PPC Land notes that in July both were near the top for ChatGPT mentions, Tesco 9th and Asda 8th, so Asda was named slightly more often than Tesco while being cited far less.
The Ford example is even starker. PPC Land reports that in July 2026 ford.com ranked 18th for ChatGPT mentions in the US but 1,055th for ChatGPT citations. On Gemini the figures were 17th and 1,146th, on AI Mode 23rd and 1,320th, and on AI Overviews 14th and 748th. The report groups brands like this, mentioned often and rarely cited, under the label "One-Way Door". Seven US domains qualified every month: Chevrolet, Disney, Ford, Honda, Marvel, Nintendo and Toyota.
The report does not explain why Asda or Ford are cited so rarely. It measures the pattern, not the cause, and any explanation about site structure or content would be a guess.
The four AI platforms behave differently
Semrush's release says Gemini names more distinct brands per answer than ChatGPT, while ChatGPT cites the most sources per answer of the four platforms and Gemini the fewest. PPC Land gives the numbers behind that: in the UK, ChatGPT averaged 12.5 to 22 source URL entries per answer and Gemini 1.6 to 4.4. These are URL entries, not unique websites, and the averages include answers with no citations at all.
Source concentration also varies. In the UK, Google AI Mode's ten leading source domains held 23.2% to 35.8% of the citations among its 10,000 most-cited UK domains, according to Semrush. For ChatGPT the top ten held 12.8% to 15.4%. AI Mode leans on a smaller set of big sources; ChatGPT spreads its citations more widely.
Google AI Overviews is the outlier. Semrush says it had the lowest brand-mention overlap with the other three platforms in all seven months, and its pairing with ChatGPT had the lowest source overlap of any platform pair in both markets. PPC Land puts that shared source figure at 42.1 out of 100 in the UK and 43.6 in the US on seven-month means. Being visible in Google's AI Overviews says little about visibility in ChatGPT, and the other way round.
The UK is more fragmented than the US
The first UK benchmark is the news hook of this edition. Semrush says any two of the four platforms shared, on average, 63 to 70 of their top 100 mentioned brands in the UK, against 70 to 78 in the US. A larger share of leading UK domains showed up on only one platform.
Semrush also defined a "Universal Core": brands in the top 100 mentions on all four platforms every month. The UK core had 24 domain records and the US core 36, with 15 shared across both, including Adobe, Apple, Amazon, Google, LinkedIn, Microsoft, Reddit, TikTok and YouTube. Nine domains were unique to the UK core, six of them in retail or ecommerce: Amazon UK, Argos, Asda, eBay UK, Marks & Spencer and Tesco. The other three were BBC, Nike and TripAdvisor UK. PPC Land points out that Adobe, which owns Semrush, sits in the shared core; nothing suggests the result was adjusted, but the ownership is relevant context.
News sources carry more weight in UK answers. On ChatGPT, news sites made up an average of 29.5% of citations among the top 100 most-cited UK domains, against 19.6% in the US. On Gemini, news was the leading UK source category every month, at 16.6% to 23.0% of top 100 citations. After news, ChatGPT's UK citations favoured trip-planning sites and online marketplaces, while US citations favoured online learning and streaming platforms.
Key figures from the Semrush AI Visibility Index
The table below collects the figures Semrush published on 13 October 2026, with the per-platform detail as reported by PPC Land from the full study.
| Measure (Jan-Jul 2026) | UK | US |
|---|---|---|
| Top-100 mentioned brands also in top-100 cited domains (all platforms) | 36.7 to 45.3 of 100 | 41.4 to 47.4 of 100 |
| Same overlap, ChatGPT only | 28.7 to 32.3 of 100 | 32.8 to 35.8 of 100 |
| Top-100 brands shared by any two platforms | 63 to 70 | 70 to 78 |
| Universal Core (top 100 on all four platforms every month) | 24 domains | 36 domains |
| News share of ChatGPT top-100 citations | 29.5% | 19.6% |
What the study does not show
The report is open about its limits, and they matter. Per PPC Land, Semrush says the index measures recurrence, not growth, and draws no link between visibility and commercial results. It does not attribute changes to model updates. PPC Land adds that the four platforms are treated equally rather than weighted by usage, and that Claude, Perplexity and Microsoft Copilot are not included. The UK data is one market-level set with no split by nation, and the Republic of Ireland is excluded.
There is also a commercial angle to keep in view. Semrush sells AI visibility and GEO software, and the report promotes its own enterprise products. The press release repeats an Adobe claim that AI-referred visitors convert 60% better than non-AI traffic and generate 53% more revenue per visit. Neither the release nor, according to PPC Land, the report says where the figure comes from. Adobe's AI traffic report of 19 August 2026, as covered by Chief Marketer and Digital Commerce 360, gives the same numbers for US retail sites in July 2026, so they describe US online retail, not brands in general, and they are not a finding of the index.
None of this makes the mention and citation data less useful. It does mean the index tells you where brands recur in AI answers, not whether that recurrence pays.
What this means for Thai marketers
The study has no Thai data. It covers the UK and US only, and nothing in it describes how ChatGPT, Gemini or Google's AI features treat Thai brands or Thai-language queries. The finding that does travel is structural: the UK and US results differed on all four platform-agreement contrasts Semrush reported, in every month, so a benchmark from one market cannot stand in for another.
What follows is Relevant Audience analysis, not a Semrush finding. A sensible starting point is a short set of category questions a Thai buyer would actually ask, run in Thai and English across the platforms that matter locally, recording two separate things each time: whether the brand is named, and whether one of its own pages is listed as a source. If the brand is named but never cited, the Asda pattern applies, and the work is on making owned pages useful enough to be picked as a source. That is the core of generative engine optimisation, and it differs by platform, which is why ChatGPT needs its own check (see ChatGPT SEO).
FAQ
What is the Semrush AI Visibility Index H2 2026?
It is a Semrush study released on 13 October 2026 that tracks how often brands are mentioned and cited in ChatGPT, Gemini, Google AI Mode and Google AI Overviews across the UK and US from January to July 2026. It is the first edition to include a UK benchmark, and it uses monthly pools of 2.5 million UK and 25 million US prompts.
What is the difference between an AI mention and an AI citation?
A mention is a brand named in the answer text, while a citation is a domain listed as a source for that answer. Semrush found fewer than half of the top 100 mentioned brands were also top 100 cited domains, so the two need separate tracking.
Why did Asda rank 606th in ChatGPT citations?
Semrush did not say why. It reported that in July 2026 Asda was ChatGPT's 606th most-cited UK domain against Tesco's 25th, even though both were in ChatGPT's top 10 for mentions, but the study measures the pattern rather than its cause.
Does the study include Thailand?
No, the index covers only the UK and US, and it excludes Claude, Perplexity and Copilot. Its useful lesson for Thailand is that results differ by market, so Thai brands need to benchmark in Thai and in Thailand rather than borrow UK or US figures.
Can I trust the 60% conversion claim?
Treat it with caution. The release does not describe the data, but Adobe's 19 August 2026 report, as covered by trade press, gives the same figures for US retail sites in July 2026, so they do not cover other sectors or markets. Adobe also owns Semrush, which sells AI visibility tools.
The Semrush data makes one point hard to ignore: an AI answer can name a brand many times without ever sending a reader to that brand's site. Tracking mentions and citations separately, per platform and per market, is the honest way to see where a brand stands. If you want help setting up that measurement for the Thai market, Relevant Audience's GEO service can start with a baseline check.
