The Open Index · Citations
Who does AI cite, and does ranking still matter?
Assistants quote a small set of sources, the set differs by industry and platform, and it overlaps less with Google’s top 10 than it did last year. Here is what five studies found.
37.9%
of AI Overview citations come from pages in the top 10
Ahrefs, January 2026
Written byKris GjorgjioskiKeyword research and industry benchmarks, Webtec Research
Checked byHristijan NajcheskiHead of SEO and AEO (technical and AI SEO), data verification
Updated October 15, 2026 · Edition 1Refreshed quarterly · next January 2027
Built from research on
Google
OpenAI
Perplexity
Gemini
Anthropic
Cloudflare
Semrush
THE RANKING QUESTION
Ranking helps. It is no longer the main way in.
Ahrefs compared AI Overview citations with the regular top results for the same keywords, twice.
Where cited pages rank
The first row is the July 2025 analysis; the others are the January 2026 data. The method changed, so compare the direction, not the decimals.
- Cited pages in the top 10 (July 2025 analysis, approx.)76%
- Cited pages in the top 10 (Jan 2026 data)37.9%
- Cited pages ranking 11 to 10031.2%
- Cited pages beyond position 10031%
SourceAhrefs · 2026
WHY IT FELL
Fan-out searches.
Ahrefs suggests AI Overviews rely more on sources appearing in the results of “fan-out” queries, the extra searches Google runs behind the scenes, rather than the original query’s top 10. That is the authors’ interpretation, not a confirmed finding, and Google does not expose the fan-out queries.[4]
The practical point: pages that answer the related questions around a topic can be cited even when they do not rank for the headline query.
BY INDUSTRY
The five domains AI quotes most, industry by industry.
Conductor, 17M AI responses and 100M+ citations, May to September 2025, US.
| Industry | Most-cited domains, in order | Share, where published |
|---|---|---|
| Health Care | mayoclinic.org, clevelandclinic.org, healthline.com, goodrx.com, webmd.com | Not published |
| Financials | nerdwallet.com, bankrate.com, kiplinger.com, vanguard.com, experian.com | NerdWallet: 6.73% of citations |
| Information Technology | google.com, microsoft.com, sap.com, dell.com, adobe.com | Google: 5.34% of citations |
| Consumer Staples | amazon.com, walmart.com, chewy.com, bestbuy.com, mattressfirm.com | Amazon: 17.99% of citations |
| Industrials | deloitte.com, indeed.com, mckinsey.com, wolterskluwer.com, siemens.com | Not published |
| Real Estate | hines.com, publicstorage.com, cbre.com, extraspace.com, colliers.com | Hines: 11.62% of citations |
| Communication Services | youtube.com, reddit.com, google.com, investopedia.com, reuters.com | Not published |
| Consumer Discretionary | clemson.edu, walmart.com, target.com, fourseasons.com, cornell.edu | Not published |
The pattern: in regulated, high-trust industries the leaders are institutions (clinics, publishers of financial guidance, big consultancies). In consumer categories they are retailers and marketplaces.[1] If your industry’s list is dominated by a handful of giants, the opportunity is the long tail of specific questions they do not answer well.
BY PLATFORM
Each assistant has its own favourites, and they change.
Semrush, 13 weekly snapshots from July 14 to October 12, 2025: 230,000+ prompts, 100M+ citations.
ChatGPT
Wikipedia and Reddit were the two most-cited domains. Reddit appeared in close to 60% of responses in early August and about 10% by mid-September; Wikipedia fell from roughly 55% to under 20%.
Google AI Mode
LinkedIn, YouTube, Reddit, Google and the Google blog led. LinkedIn appeared in nearly 15% of responses. Google favours its own domains.
Perplexity
Reddit, LinkedIn, NIH, Microsoft and Google led. Reddit’s visibility dipped slightly in September; Wikipedia’s share was about 0.8%.
Semrush notes it cannot say exactly why the shifts happened.[2]
WHAT GETS CITED
Reference sites, forums, and government sources.
Pew compared what Google’s AI summaries cite with what standard results link to, across 68,879 searches.
Share of sources: AI summaries vs standard results
AI summaries lean more on .gov sites; Wikipedia, YouTube and Reddit are similar in both.
Wikipedia, YouTube and Reddit
- In AI summaries15%
- In standard results17%
.gov websites
- In AI summaries6%
- In standard results2%
News sites
- In AI summaries5%
- In standard results5%
WHAT RESEARCHERS SAY WORKS
Be quotable.
The first academic study of optimizing for generative engines, accepted to KDD 2024, built a benchmark of queries across domains and reported that generative-engine optimization methods can raise visibility by up to 40%, noting the effect differs by domain.[5]
Pew found 88% of AI summaries cite three or more sources, with a median summary length of 67 words:[3] short, specific, well-sourced passages are the unit of citation. Google’s guidance is the same in spirit: helpful, people-first content, no special markup.[6] And cited brands kept a higher organic CTR than uncited ones in Seer’s data.[7]
OUR INTERPRETATION
What we make of the numbers.
The figures above are the studies’. This part is our reading of them, kept separate so you can disagree.
Webtec Research
Our interpretation
- Kris GjorgjioskiKeyword research and benchmarks
- Hristijan NajcheskiTechnical SEO, data checks
- Figures: the cited studies
- Reading: ours
The figures on this page come from the cited studies. This reading of them is ours, and you may weigh it differently.
Two facts from this page matter most. First, citations are concentrated: in many industries five domains take a large share of what AI quotes. Second, the list moves: one platform’s favourites changed within weeks in 2025.
Together they argue against a shortcut. There is no stable list of sites to copy, and no trick that works everywhere. What the cited sources share is depth, evidence and being referenced elsewhere. For a smaller firm, the realistic route is to win specific questions, not whole topics, and to publish original data or well-sourced explanations that others cite in turn.
We would treat citation share as something to monitor, not a number to chase.
- Pick ten questions your buyers ask and test them on three assistants
- Publish original, dated, sourced answers with named authors
- Re-test monthly, because the list changes
Cite this page.
Please link back and credit Webtec Research.
CITE THIS PAGE
Webtec Research. (2026, October 15). Who AI cites: the domains behind AI answers, by industry. The Open Index by Webtec. https://www.trywebtec.com/resources/index/ai-citations/
Questions about AI citations.
Which websites do AI assistants cite most?
It varies by platform and week. Semrush’s 13-week study (July to October 2025, 230,000+ prompts, 100M+ citations) found Wikipedia and Reddit were ChatGPT’s two most-cited domains, LinkedIn and YouTube were among Google AI Mode’s top sources, and Reddit topped Perplexity. Conductor’s industry data shows each industry has its own leaders, from Mayo Clinic in Health Care to NerdWallet in Financials.
Do I have to rank in the top 10 to be cited?
No. Ahrefs found 37.9% of AI Overview citations came from pages ranking in the top 10 (863,000 keyword SERPs, 4M cited URLs, data as of January 2026), down from about 76% in its July 2025 study. The method changed between studies, so the exact drop is uncertain, but the direction is clear: ranking helps, and many cited pages rank outside the top 10.
Can the cited sources change quickly?
Yes. Semrush saw ChatGPT’s citations of Reddit fall from close to 60% of responses in early August 2025 to around 10% by mid-September, and Wikipedia from roughly 55% to under 20%, while AI Mode and Perplexity stayed steady. Platform changes can reshuffle who gets cited in weeks.
What kind of content gets cited?
Pew found Wikipedia, YouTube and Reddit made up 15% of AI summary sources, and .gov sites 6% against 2% in standard results. The GEO research paper reported that content changes such as adding citations, quotations and statistics could raise visibility in generative engine responses by up to 40%, with the effect varying by domain.
Is there a special markup for AI citations?
Google says there is no special schema or file needed to appear in AI Overviews or AI Mode. Pages must be indexed and eligible to appear with a snippet, and Google recommends helpful, people-first content.
Which industry has the most concentrated citations?
In Real Estate, Hines took 11.62% of citations and Public Storage 10.49% in Conductor’s data. In Consumer Staples, Amazon alone took 17.99%. Concentration means a few domains absorb most of the visibility, which makes the remaining slots harder to win.
Does brand size decide who gets cited?
Large recognised brands dominate many lists, such as Mayo Clinic in Health Care and NerdWallet in Financials. The studies do not prove size is the cause: these are also the sites with the deepest, most referenced content on their topics.
Is it better to be cited by one assistant or many?
Many. Semrush showed citation patterns shift quickly on one platform while staying steady on others, so a single-platform strategy is fragile. Testing your key questions on several assistants every month is a sensible habit.
Do Reddit and YouTube really matter for citations?
They appear among the most-cited domains in several datasets, including Pew’s and Conductor’s Communication Services list. That suggests discussion and video content is a source for AI answers, though Semrush also found ChatGPT’s use of Reddit dropped sharply within weeks in 2025.
How can a small business get cited?
Be the clearest, best-sourced answer to a narrow question your buyers ask, with a named author and a date. The GEO research paper found adding citations, quotations and statistics could raise visibility in generative responses by up to 40%, with effects that vary by domain.
SOURCES
Sources and notes
7 sources on this page: 3 independent or official (grade A) and 4 vendor or agency studies with a disclosed method (grade B). Numbers in brackets in the text match the numbers below. We read every figure on the source’s own page. How we grade sources.
- What we use:
- AI Overview prevalence and AI referral share by industry; ChatGPT’s share of AI referrals; most-cited domains by industry.
- Period:
- May to Sept 2025 (AI Overviews: Sept 15 to Oct 12, 2025)
- Sample:
- 13,770 enterprise domains in 10 industries; 17M AI responses and 100M+ citations; AI referral data from 1,215 domains (3.3B sessions, 35.7M AI sessions); 21.9M US Google searches for AI Overviews.
- Read with care:
- US data. AI Mode traffic is excluded because Google Analytics groups it with organic Google traffic. Some figures appear twice with different rounding; we use the more precise one.
- Vendor studyGrade BPublished 2025-11-10Read the source
- What we use:
- Which domains AI assistants cite most, and how fast that mix changed.
- Period:
- July 14 to Oct 12, 2025 (13 weekly snapshots)
- Sample:
- 230,000+ prompts and 100M+ AI citations across ChatGPT search, Google AI Mode and Perplexity.
- Read with care:
- Most shares appear only in charts; we use the figures given in the text.
- Independent researchGrade APublished 2025-07-22Read the source
- What we use:
- Click and session behaviour with and without AI summaries; share of searches with a summary; which sources summaries cite.
- Period:
- March 2025
- Sample:
- 900 US adults tracked in KnowledgePanel Digital; 68,879 Google searches.
- Read with care:
- A US panel; does not measure publisher revenue.
- Vendor studyGrade BPublished 2026-03-02Read the source
- What we use:
- How many AI Overview citations come from pages ranking in the top 10.
- Period:
- AI Overviews as of January 2026
- Sample:
- 863,000 keyword SERPs and 4M AI Overview URLs (Ahrefs Brand Radar).
- Read with care:
- Parsing method changed since the 2025 study, so the comparison is not like-for-like.
- What we use:
- The first formal study of optimizing for generative engines; reports visibility gains of up to 40%.
- Period:
- v3 revised June 28, 2024
- Sample:
- GEO-bench, a benchmark of diverse queries across domains.
- Read with care:
- The authors note efficacy varies across domains.
- What we use:
- What Google says is and is not required to appear in AI features.
- Period:
- Documentation, last updated Dec 10, 2025
- Sample:
- Google’s own guidance for AI Overviews and AI Mode.
- Agency studyGrade BPublished 2025-11-04Read the source
- What we use:
- Organic and paid CTR with and without AI Overviews, and the effect of being cited.
- Period:
- June 2024 to September 2025
- Sample:
- 3,119 informational and educational search terms across 42 organizations; 25.1M organic and 1.1M paid impressions.
- Read with care:
- Retrospective cohort; paid sample is small; the page has small internal inconsistencies, so we use the Q3 2025 averages and endpoint values.
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A LIVING REFERENCE
Refreshed every quarter.
We re-check every source in January, April, July and October, add new studies and retire old ones. This is Edition 1 (October 15, 2026); the next is due January 2027. Changes are logged on the methodology page.
