ChatGPT stopped searching only the open web on 8 August and started asking named websites directly. Six days later, Reddit’s share of the citations ChatGPT returns had fallen by 86%.

The figures come from Promptwatch, an Amsterdam-based AI-visibility firm that tracks reddit.com’s daily share of every citation returned by ChatGPT Search. Reddit averaged 3.83% of those citations between 18 July and 7 August, one of the largest shares held by any single domain on the web. Between 14 and 17 August it averaged 0.52%.

For marketing teams the number that matters is not Reddit’s. It is the one underneath it. The share of ChatGPT’s background searches scoped to one named domain rose from 0.37% to 16.8% in a single day and has held there since, according to the same tracker. A retrieval system that goes to named sites and asks them rewards different preparation from one that reads whatever the open web returns, and a large share of the generative engine optimisation sold over the past two years was designed for the second.

What changed inside ChatGPT on 8 August?

ChatGPT began using the site: search operator at scale on 8 August, scoping a substantial share of its own background queries to one domain at a time. Promptwatch monitors the queries the assistant writes for itself when it breaks a prompt into web searches. It recorded that share rising from 0.37% to 16.8% of all fan-out queries in a day, roughly a 46-fold increase. The share has held at 16% to 17% since.

The second measurement is what shows the change was additive rather than a swap. The average number of searches ChatGPT runs per response nearly doubled over the same period, from about 1.08 to 1.83. Had the assistant simply replaced its old queries with domain-scoped ones, that average would have stayed flat. Instead the named-site searches appear to have been stacked on top of the broader ones already running.

Klaas Foppen, Promptwatch’s co-founder, described the assistant as now “deliberately going to specific sites to pull information from them”, in comments reported by Search Engine Journal. Discussion platforms are rarely the target of a domain-scoped query about a brand or a product. Official sites, product documentation and institutional domains are, which gives a plausible mechanism for a citation collapse that hit forums hardest.

How far did Reddit’s citation share actually fall?

Reddit’s decline came in two steps rather than one. Its share slipped from the high threes into the mid twos on 8 August, the day the search behaviour changed, then broke below 1% on 14 August and stayed there, producing the 86.4% relative fall Promptwatch published on 20 August.

Google’s AI surfaces moved differently over the same window, which is what points the cause at ChatGPT rather than at Reddit. Reddit’s share of Google AI Overviews citations fell from about 2.37% to 2.10%, a relative decline of 11.3%, and its share in Google AI Mode from 2.22% to 1.54%, down 30.5%. Both declined gradually, with no single break point.

The figures carry two caveats the coverage has largely dropped. Promptwatch states that the size of the drop is provisional and that a collection-side artefact on its own end has not been ruled out. Search Engine Journal’s Matt G. Southern noted the six-day gap between the 8 August search change and the 14 August collapse, which is consistent with the site: operator explanation without establishing it.

Reported figures also differ. Gizmodo, which broke the story on 18 August, put Reddit’s pre-drop share as high as 4.5% of ChatGPT outputs, above the 3.83% average Promptwatch published. Forbes, drawing on the same tracker, reported Reddit as the single most-cited domain in ChatGPT Search as recently as April, at 4.14%. OpenAI did not respond to Gizmodo’s questions about the change and has published no explanation of it. A Reddit spokesperson told Gizmodo the platform remains one of the most-cited domains according to other studies. Reddit does not depend on large language models for traffic, the spokesperson said, taking most of it from direct visits and conventional search.

What does a domain-scoped search change for AI-visibility work?

Promptwatch’s practical reading is that a brand’s own domain has become a more important retrieval surface than it was in early August. A domain-scoped query can only surface what is already indexed from the site it names. That puts thin or unindexed pages on the wrong side of a second mechanism, on top of the ranking one they were already losing.

The firm suggests four checks, none of which require new tooling. Compare which Reddit URLs were cited before and after 14 August, since a broad loss points to the platform-wide change and a loss concentrated in a few subreddits points somewhere else. Check whether GPTBot activity on the domain changed after 8 August, because a system asking a site directly should show up in crawler logs before it shows up in citation counts. Re-run fan-out analysis on tracked prompts, as keyword-to-prompt mappings built before 8 August describe a search behaviour that no longer exists. And confirm the pages a named-site query would need are indexed at all.

None of this makes the teams who invested in Reddit wrong. Reddit was, on the same tracker, among the most-cited domains in ChatGPT for two years. The Marketing Helm reported on 7 August that an industry of agencies had grown up selling brand mentions seeded into subreddits as a route to AI citation. That route lost most of its ChatGPT value in a week, on an engineering decision nobody outside OpenAI was told about. The exposure was concentration, not judgement. Steve Rubel, executive vice-president for media insights at Burson, told Axios that a single reliable route into AI answers is a “mythical unicorn”, and that visibility is a long game played across many channels.

Two distinctions survive the week. Reddit’s citation share in Google AI Overviews barely moved, so any blended AI-visibility score would have hidden the split entirely, which is an argument for tracking engines separately rather than as one figure. And a citation is not a mention: Reddit threads still shape how a brand is described inside a synthesised answer even when no reddit.com URL appears beneath it. The Helm reported separately that ChatGPT often names brands in its own first query before fetching any page, a finding that points at the same machinery from the other side.

OpenAI has not said what changed on 8 August, and Promptwatch describes the size of the drop as provisional. Reddit joined the S&P 500 on 18 August, four days after its ChatGPT citation share fell below 1%.