Weekly index · week 40 edition
Reddit in AI search: week 40
How much each AI model cites Reddit in its answers, week by week, and where that presence is changing.
This is the week 40 edition, kept as published. See the current edition →
In short
In week 40, Google AI Overviews was the model that cited Reddit most, in 27.7% of answers, followed by Google AI Mode (16.5%). Significant change from the previous week: Google AI Overviews (−4.2 pp), Google AI Mode (+2.7 pp). Since week 1, the largest drop is Grok's (−39.7 pp) and the largest rise is Google AI Overviews' (+15.4 pp).
In week 40, by model
Share of answers citing Reddit and change from week 39.
Timeline
Weekly presence since week 1. Each panel has its own scale; compare the shape of the curves, not heights across panels. Hollow circles mark weeks with a reduced base; blue markers are events, click to see them.
All weeks
Week 40 ranking
| Model | Presence | Week change | 4-week avg. | Since W1 | Change |
|---|---|---|---|---|---|
| 1. Google AI Overviews | 27.7% | ↓ −4.1 pp | 31.8% | ↑ +15.4 pp | Significant |
| 2. Google AI Mode | 16.5% | ↑ +2.7 pp | 11.5% | ↑ +7.1 pp | Significant |
| 3. Gemini | 4.1% | ↓ −0.7 pp | 4.2% | ↑ +4.0 pp | Within noise |
| 4. Perplexity | 2.7% | ↓ −0.6 pp | 3.5% | ↓ −34.1 pp | Within noise |
| 5. Grok | 1.9% | ↓ −0.7 pp | 1.3% | ↓ −39.7 pp | Within noise |
| 6. ChatGPT | 0.4% | ↓ −0.1 pp | 0.5% | ↓ −20.7 pp | Within noise |
| 7. Copilot | 0.0% | → 0.0 pp | 0.0% | → 0.0 pp | Within noise |
Presence: share of the model's answers that cite reddit.com among their sources. Changes in percentage points (pp).
Events
Large changes in the series and what is known about them. We only log explanations with a source; when there is none, we say so.
- W35 · Aug 24–30 Reduced base Google AI Overviews had a much smaller base than usual in week 35. The same week, Google AI Mode drops to 3.9%, stays between 7% and 9% through week 38 and returns to its 13–17% range from week 39.
- W34 · Aug 17–23 No explanation found Google AI Overviews jumps from 5.5% (week 33) to 21.4% and, from week 36, stays between 26% and 35%, nearly double its first-half average (13.9%). We found no announcement or public measurement of this step.
- W33 · Aug 10–16 Observed by third parties ChatGPT: Reddit's presence falls from 16.9% (week 32) to 7.7% and then 2.1%, and has stayed under 1% since week 35. Measurements by Promptwatch and DevTune recorded the same drop in ChatGPT citations, in two steps (August 8 and 14). Neither OpenAI nor Reddit has confirmed the cause. Source: Search Engine Journal ↗ · Source: DevTune ↗
- W24 · Jun 8–14 No explanation found Grok returns after two weeks without data (May 25 and June 1) at 9.1% presence, against 57–65% in May, and stays under 3% from August. We found no public announcement that explains the change.
- W22–W23 · May 25–Jun 7 Collection note No Grok data in weeks 22 and 23 (May 25–Jun 7): changes to Grok's mechanism prevented data capture in that period. The drop in presence seen after collection resumed is logged separately, in week 24.
- W19 · May 4–10 Observed by third parties ChatGPT: Reddit's presence rises from 13.7% (week 18) to 27.6% and to 39.0% the following week, and swings between 20% and 39% through late June. The same week, OpenAI began switching the default model to GPT-5.5 Instant, and a Writesonic test saw Reddit become the most-cited domain on that version. OpenAI has not commented on the link. Source: Writesonic ↗ · Source: GIGAZINE ↗
- W16 · Apr 13–19 Reduced base Copilot had a smaller-than-usual base in week 16; comparisons involving that week are not assessed.
- W10 · Mar 2–8 Possible ChatGPT: Reddit's presence falls from 16.5% (week 9) to 7.9% and to 4.6% the following week. The same week, on March 3, OpenAI made GPT-5.3 Instant the default model, described as less likely to lean on web results. No one has linked that change to Reddit. Source: The Decoder ↗ · Source: ALM Corp ↗
- W9 · Feb 23–Mar 1 Observed by third parties Perplexity starts to decline: from 39.5% (week 8) to 28.6% and 21.0% over the next two weeks, and to 8.2% in week 17; since June it has stayed between 1.4% and 5.3%. Tinuiti, using Profound data, recorded the same drop in Reddit's share of Perplexity citations between February and April, without identifying the reason. Source: MediaPost ↗ · Source: Shopifreaks ↗
Method, in short
Source: data observed and catalogued by First Answer. Each week, we measure by model the share of answers that cite reddit.com among their sources and compare it with the previous week. A change is flagged as significant only when it exceeds the 95% margin and is at least 1 pp. Weeks with a smaller-than-usual base are flagged and left out of the comparison.
Limitations
The index measures what First Answer's base observes, not every search made on the models. We do not disclose volumes, questions, topics, categories, brands or clients; only aggregate measures by model. Claude is not included in this series. Explanations under Events come from external sources and state how confirmed they are.
How to cite
Beckmann, R. (2026). Reddit in AI search: weekly index (week 40, Sep 28–Oct 4, 2026). First Answer. https://rodrigobeckmann.com/en/research/indices/reddit-in-ai-search/2026-w40