The most cited sources in ChatGPT are Wikipedia, cited in 4.88 million answers, and Reddit, cited in 3.25 million. Google AI Overviews lean on a different set of sites: YouTube leads with 51.9 million citations, more than twice Reddit’s 25.1 million, according to DataForSEO’s Search Insider 2026.
The two lists split along clear lines. Google’s top 10 is full of video and social platforms. ChatGPT’s leans toward reference sites, health publishers and news outlets. And ChatGPT left 27.3% of its answers without any source at all, against 0.7% for AI Overviews.
This post is part of our series on the Search Insider 2026 findings. It covers both top-10 lists, where they diverge, why other rankings you’ve seen look different, and how the pattern compares with AmICited’s own tracking.
Key Takeaways
- YouTube is the most-cited domain in Google AI Overviews with 51.9M citations, but only 19th in ChatGPT, with 211K answers citing it.
- Wikipedia leads ChatGPT with 4.88M citing answers and ranks 4th in AI Overviews with 19.9M citations.
- Reddit is 2nd on both platforms: 25.1M citations in AI Overviews and 3.25M citing answers in ChatGPT.
- 27.3% of ChatGPT answers had no source citation, compared with 0.7% of AI Overview answers.
- Reuters, The Guardian, AP News and The Washington Post are in ChatGPT’s top 30 cited domains but not Google’s. Facebook, Instagram and TikTok are in Google’s top 10 but not ChatGPT’s top 30.
The top 10 on each platform
Google AI Overviews and ChatGPT agree on Reddit at number 2 and disagree on almost everything else. YouTube, Facebook and Instagram dominate Google’s list. Wikipedia, Britannica and NIH lead ChatGPT’s. The counts can’t be compared across platforms, because each list is ranked within its own corpus.
| Rank | Google AI Overviews | Citations | ChatGPT | Citing answers |
|---|---|---|---|---|
| 1 | youtube.com | 51.9M | wikipedia.org | 4.88M |
| 2 | reddit.com | 25.1M | reddit.com | 3.25M |
| 3 | facebook.com | 20.4M | fandom.com | 670K |
| 4 | wikipedia.org | 19.9M | britannica.com | 486K |
| 5 | google.com | 15.9M | nih.gov | 476K |
| 6 | instagram.com | 11.9M | healthline.com | 369K |
| 7 | quora.com | 5.8M | legalclarity.org | 358K |
| 8 | fandom.com | 5.6M | apple.com | 357K |
| 9 | amazon.com | 5.4M | yahoo.com | 351K |
| 10 | tiktok.com | 5.2M | alibaba.com | 347K |
ChatGPT’s list is far more concentrated at the top. Wikipedia and Reddit together are cited in more answers than the next eight domains combined, and Reddit alone appears in almost five times as many answers as Fandom in third place. Google’s curve is flatter, with five domains above 15 million citations.
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Where the two lists split
The split between ChatGPT and Google AI Overviews follows content type. Six of Google’s top 10 are social, video or community platforms (YouTube, Reddit, Facebook, Instagram, Quora, TikTok). ChatGPT’s top 10 holds reference sites (Wikipedia, Britannica), health sources (NIH, Healthline) and a legal explainer site. By our count of DataForSEO’s Table C3, 16 domains appear in both top-30 lists.
The 14 domains unique to each list tell the story:
| Only in Google AI Overviews’ top 30 | Only in ChatGPT’s top 30 |
|---|---|
| Facebook, Instagram, TikTok, Pinterest, LinkedIn, Spotify, Medium | Reuters, The Guardian, AP News, The Washington Post, New York Post, India Times, People |
| Quora, JustAnswer, Study.com, Yelp | Forbes, Screen Rant, Indeed, LegalClarity |
| Amazon, eBay, Walmart | Alibaba, Biology Insights, Enviroliteracy |
Google cites social networks and marketplaces that ChatGPT barely touches. ChatGPT cites news publishers that don’t make Google’s list. YouTube is the sharpest case: first in AI Overviews, 19th in ChatGPT. For more on why video does so well in Google’s answers, see why YouTube is the most cited source in AI Overviews.
Answers with no citation
ChatGPT answers far more questions without naming a source. In DataForSEO’s corpus, 27.3% of ChatGPT answers carried no source citation, compared with 0.7% of Google AI Overview answers. More than one in four ChatGPT answers gives a reader nothing to click and gives a brand no citation to earn.
None of the AI engines we asked about these rankings on November 7, 2026 mentioned this gap. They quote citation shares, which only describe the answers that do cite something.
The figure is a blend. The ChatGPT corpus runs from July 2025 to September 2026 and spans models from GPT-4o through GPT-5.6, so the rate for today’s default model may be higher or lower. The direction still matters: in ChatGPT, a brand can shape an answer from the model’s own knowledge without any link. Our study of 107,432 AI brand mentions found 56.5% carried no citation link, which points the same way.
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Why ChatGPT cites news sites more
ChatGPT cites news publishers more than Google AI Overviews do, at least among the most-cited domains. Reuters (242K citing answers), The Guardian (226K), AP News (156K) and The Washington Post (139K) sit in ChatGPT’s top 30. None of them appears in Google’s top 30. DataForSEO reports the pattern but doesn’t test a cause.
Two factors may contribute. Neither is proven by this data:
- Publisher deals. OpenAI has content partnerships with news publishers. When The Washington Post signed in April 2025, TechCrunch reported that ChatGPT would summarize and link to the Post’s reporting, and that OpenAI had deals with over 20 news publishers, including The Guardian.
- Different source pools. Google’s top 30 includes its own properties (YouTube, google.com) and large social platforms. If those take a big share of Google’s citations, publishers have less room in its top 30.
Treat both as hypotheses. The practical point holds either way: earned coverage in major publications is more visible in ChatGPT’s most-cited sources than in Google’s.
Why other rankings differ
Other most-cited-domain studies agree on the leaders but give different numbers, because they measure different things. Ahrefs reports share of the top 50 sources’ citations. Similarweb reports share of citation events. DataForSEO reports raw counts. Prompt sets and dates differ too.
- Ahrefs puts YouTube at 24.5% of AI Overview citations, Reddit 18.1%, Facebook 12.4% and Google 8.6%, with Wikipedia 7th at 4.4%. That share is each domain’s citations divided by the top 50 sources’ total, across over 3 million US queries ( Ahrefs, updated November 3, 2026).
- Similarweb puts Wikipedia at 13.15% and Reddit at 11.97% of ChatGPT citation events in the US in January–February 2026 ( Similarweb).
- DataForSEO counts citations across 137.9M AI Overview answers and 27.5M ChatGPT answers over about a year, and doesn’t convert them to shares.
Wikipedia ranks 4th in DataForSEO’s AI Overview list and 7th in Ahrefs’. That’s a difference in sample and date, not a contradiction. Reddit is the other moving part: its ChatGPT citations fell sharply in August 2026, and DataForSEO’s ChatGPT window runs through September 6, 2026, so its count mixes months before and after the drop.
What our own tracking shows
AmICited’s own data ranks the leaders differently, because our prompts are about products, not general knowledge. In our tracking from June 24 to July 23, 2026, YouTube was cited in 4.8% of 2,010 AI Overview responses, the most of any domain. In ChatGPT, Reddit led at 7.3% of 5,119 responses, followed by TechRadar (7.1%) and Shopify (6.6%). Wikipedia wasn’t in ChatGPT’s top 20.
The lesson for brands: the global top 10 tells you how each engine behaves in general. The sources that matter for your buyers’ questions can be quite different, and you only see them by tracking your own prompts.
What brands should do now
- Track each engine separately. Google AI Overviews and ChatGPT draw on different sources, so a single “AI visibility” number hides the difference. Prompt Tracking runs the same prompts in each engine as a separate result.
- Find the sources cited for your prompts. Source & Citation Intelligence lists the domains and URLs each engine cites for your tracked prompts. Compare that list with the global top 10 before you decide where to invest.
- Match the format to the engine. For AI Overviews, video and community content matter more. UGC Influence shows which YouTube videos and Reddit threads are cited in your category. For ChatGPT, reference pages and press coverage carry more weight, so check your Wikipedia eligibility and your earned media.
- Measure mentions, not only citations. With 27.3% of ChatGPT answers carrying no source, a citation count misses part of your visibility. The ChatGPT visibility tracker records whether ChatGPT names your brand as well as which pages it cites.
The takeaway
Google AI Overviews and ChatGPT reward different kinds of sites. Google leans on YouTube, Reddit and social platforms. ChatGPT leans on Wikipedia, Reddit, reference sites and news publishers, and answers more than a quarter of questions without any citation. Reddit is the only domain near the top of both.
For a brand, that means two source strategies, not one, and a way to see which sources actually appear for your own prompts. For the Google search side of the Reddit story, read how Reddit shows up in Google’s top 10, and for older background on how ChatGPT finds information, see ChatGPT citation sources.
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