Disclosure: Promvia runs this index and this sub. This is the first two published weeks (3 and 7 September 2026) read side by side. It was first written up on our blog on 11 September; that article was later corrected, and only the numbers that can be recounted from the public rows are repeated here.
There is no shared list of sources
Each week the six engines together cited 858 (W36) and 851 (W37) distinct domains across 240 answers. They did not draw on them evenly:
- Gemini cited reddit.com for 26 of 40 questions in W36 and 22 in W37, and youtube.com for 25 and 20.
- ChatGPT (the API lane) cited reddit.com for 0 of 40 questions in both weeks. Its most cited domains in W37 were youtube.com (10), techradar.com (9) and forbes.com (6).
- Claude cited reddit.com for 0 of 40 in both weeks and youtube.com once in two weeks. No single domain appeared in more than 3 of its 40 answers in either week.
- Perplexity spread thin too: its most cited domains in W37, forbes.com and reddit.com, appeared in 4 of its 40 answers each.
- Google AI Overviews cited youtube.com for 24 and 25 of 40, reddit.com for 18 and 20. Google AI Mode cited youtube.com for 19 and 25, but reddit.com for only 5 and 3.
So "being cited by AI" is a fact about one engine, not about AI in general. A site that Gemini or AI Overviews picks up through Reddit threads may be invisible to ChatGPT's API lane and to Claude on the same questions.
Method: 40 fixed English buyer questions, asked once of each engine per week. Counts are answers citing the domain, out of 40 per engine (every engine answered all 40 in both weeks). A domain counts once per answer.
Caveats
- Two weeks is two weeks. Where something held in both, these two runs agreed; that is not the same as stable.
- The two weeks are four days apart.
- The ChatGPT lane is OpenAI's API (gpt-4o-mini with web search), not the ChatGPT app.
- The original blog post also reported source categories (media, community, directories) and how often a cited source is named in the answer text. Those numbers come from a classifier applied when the page is read, not from the published rows, so they are not repeated here.
- That post also contained a claim built on the Bing proxy column, which has since been withdrawn. See the correction post.
Rows and write-up
- W36: https://promvia.app/api/public/ai-source-index/rows?week=2026-W36
- W37: https://promvia.app/api/public/ai-source-index/rows?week=2026-W37
- CSVs: https://github.com/sayaranil/ai-source-index (data/citations.csv)
- Blog post, with its corrections in place: https://promvia.app/blog/what-ai-engines-actually-cite
Source: r/AISourceIndex · by /u/woodoo139