Reddit Citation StudyChatGPT cut reddit.com’s share of its citations by 89%
The two days it happened
Reddit Citation StudyWhy the first step needs a caveat and the second does not
On 8 August ChatGPT began returning far more citations per answer: the tracked total went from about 21,040 a day to about 41,393. Part of that first step down in share is therefore the denominator growing, not reddit.com shrinking. Only part, though — reddit.com’s raw count fell by roughly half on the same day.
The second step has no such ambiguity. On 14 August the total held steady while reddit.com’s raw count fell by about 60% in a day. And over the whole period the two metrics agree: the share fell 89% and the raw count per day fell 87%, from 843 to 113. A denominator effect cannot produce that.
Pick an engine, pick an industry
Reddit Citation StudyThe other engines, day by day
Reddit Citation StudyAll 16 reports fell, in 16 industries
| Industry | Baseline | After 14 Aug | Citations after 14 Aug | Change |
|---|---|---|---|---|
| Industrial/Manufacturing | 5.17% | 0.07% | 20 | -99% |
| Government | 2.89% | 0.04% | 11 | -99% |
| Nonprofit | 2.70% | 0.06% | 15 | -98% |
| Educational Platforms | 7.09% | 0.21% | 54 | -97% |
| Pharma | 0.80% | 0.02% | 8 | -97% |
| Real Estate | 6.47% | 0.26% | 61 | -96% |
| Finance/Insurance | 2.45% | 0.14% | 37 | -94% |
| Energy | 2.72% | 0.26% | 64 | -90% |
| Transportation | 2.09% | 0.22% | 44 | -90% |
| Consumer Goods | 5.42% | 0.75% | 120 | -86% |
| Retail & E-commerce | 6.48% | 0.94% | 141 | -86% |
| Hospitality | 4.07% | 0.89% | 190 | -78% |
| Media/Entertainment | 5.31% | 1.18% | 293 | -78% |
| Sports Brands | 5.49% | 1.41% | 266 | -74% |
| Technology | 2.71% | 0.86% | 206 | -68% |
| Healthcare | 1.27% | 0.53% | 52 | -58% |
The control: what the other six engines did
| Engine | Baseline | After 14 Aug | Change |
|---|---|---|---|
| ChatGPT | 4.01% | 0.44% | -89% |
| Google AI Mode | 4.01% | 3.05% | -24% |
| Google AI Overviews | 4.96% | 5.12% | +3% |
| Perplexity | 2.39% | 2.54% | +6% |
| Gemini | 1.13% | 1.28% | +13% |
| Copilot & Claude | 0.01% | <0.01% | too few to compare |
What this means
The obvious explanation is that Reddit changed: less content, worse content, a licensing dispute, a crawler block. The data does not support it. If the cause sat on Reddit’s side, every engine that reads Reddit would move together. Instead one engine dropped 89% while Google AI Overviews, Perplexity and Gemini held their level or gained.
- It is not a volume artefact. Every number here is a share of each engine’s own citations, and ChatGPT’s own volume did not shrink: it cited 23% more per day after 14 August than before 8 August. More citations, far fewer of them from Reddit.
- It is not one industry. Sixteen reports across sixteen industries, from government to pharma to retail, all move the same way in the same week.
- It is not gradual. A supply-side decay would slope. This steps, twice, on two specific days.
- Nothing hit zero. The two smallest industries still kept single-digit citation counts after 14 August, and even Copilot and Claude, which effectively ignore reddit.com, are not at zero. ChatGPT did not stop citing Reddit; it demoted it by about a factor of ten.
- Google AI Mode is the interesting exception. It fell 24%, then partly recovered in the last window. ChatGPT did not recover. A shared cause would not produce one permanent break and one temporary dip.
What is left is a change in how ChatGPT selects sources, made on ChatGPT’s side. This study measures one domain and does not identify the mechanism; establishing what replaced reddit.com, and whether the substitution is systematic across source types, is the next piece of work.
For anyone doing GEO work, the practical read is this. A single engine can remove an entire class of source in one day, without warning and without an announcement. Visibility that rests on one platform’s treatment of one domain is not visibility you control. The reports that lost least were the ones whose citations were spread across more kinds of source to begin with.
Method and limits
Scope. All 16 OtterlyAI brand reports in the United States, 28 July to 27 August 2026, across the seven AI engines tracked: ChatGPT, Google AI Mode, Google AI Overviews, Perplexity, Gemini, Copilot and Claude. 3,194,763 citations in total. The German and French markets were excluded: they have no data in the baseline window, so including them would have injected false zeroes.
Metric. reddit.com citations divided by that engine’s total citations in the same window, pooled rather than averaged across days, so a quiet day does not count as much as a busy one. Windows were chosen around the two break dates, not to flatter the result.
The small numbers were measured, not inferred. Ranked-domain responses are capped, so a domain that falls out of the top 250 comes back missing rather than as a number. Every cell that came back missing was re-queried against the cited-URL endpoint, which lists reddit.com URLs and their counts individually with no cap, and the two methods agree exactly where both return a value (63 = 63 on the cell we used to check). For ChatGPT, not one report or window is a true zero — the smallest are single-digit citation counts, and they are printed as counts in the table above rather than left to rounding. At daily resolution 56 individual report-days out of 496 are genuine zeroes: one industry, on one day, with no reddit.com citation at all.
Granularity. Nothing here is projected, modelled or interpolated. Every figure is a measured total returned by the API. What varies is how the window was requested: the daily charts use one request per day, the four-window comparisons use one request per window, and a window request returns the real sum of its days. The seven-engine daily breakdown was pulled for one report only, Retail & E-commerce; every other figure covers all 16. Reports are identified by industry throughout: each of the 16 covers a different one, so the industry names them without ambiguity.
Audit. Every figure was re-measured a second time, independently, before publication. ChatGPT was pulled twice at two different granularities — 496 single-day requests and 64 window requests — and the day-level sums reconcile with the window figures in all 64 cells. The other four engines that cite reddit.com were re-pulled cell by cell, 256 cells, and 252 matched exactly; the four that did not were all in the final window, all off by between one and eleven citations, consistent with the most recent days still settling rather than with an error. The fresher values were adopted. The ChatGPT daily series was then re-pulled in full as well, all 496 report-days, and every one matched. Two genuine mistakes were found and fixed along the way: one report-week whose day-level figures had been recorded wrongly, and the missing-means-zero problem described above.
The page was checked too, not just the data. Every number printed here is recomputed from the source files by a separate script that shares no code with the one that builds the page, and compared against what the page actually says: 1,090 checks, including all 16 rows of the per-report table, all six engine rows, and every figure quoted in the prose. Separately, the charts are read back out of the rendered page — each plotted point is converted from its pixel position back to a value using the chart’s own axis and compared with the underlying number: 273 points across the three charts. Both pass with nothing outstanding.
Other trackers. Published figures elsewhere use different prompt sets and different denominators, so the absolute percentages will not match ours and are not expected to. The shape and the dates are what should agree, and they do.
Last window. Tracked volume runs lower from 25 August. Those points are noisier; the conclusions rest on the full fortnight, not on the final days.