LinkedIn ended September cited 39% more often across AI Search than at the start of the month Reddit rose 9%. Facebook rose 16%. That is the first sustained climb social platforms have had since the 8 August ChatGPT change, and on Perplexity and Google AI Mode it is steep enough to see without a trend line.
The social category as a whole did not grow in September, because the biggest platform (YouTube) in it went the other way -42%.
Key Findings
- LinkedIn rose 39% through September, from 0.407% of all citations on 1 September to 0.564% on 20 September, measured across all seven AI Search engines.
- YouTube fell 42% in the same window, from 2.221% to 1.292%, and the fall is a single step around 13 to 15 September rather than a drift.
- The social category still shrank month over month. Roughly 4.3% of AI citations went to social media platforms in September, against 5.14% in August, a fall of -16%.
- Reddit is now the largest social source in AI Search at 1.714%, having been overtaken by YouTube for most of the summer.
- Gemini did not cite LinkedIn once in the September window.
Why This Matters for AI Search
Social platforms are not one surface. For most of 2026 they moved together, which made “social” a usable planning unit. In September they stopped.
If you have been tracking a single social number, it told you the category fell 16% and nothing else. Underneath, the platform your brand actually lives on either gained a third of its visibility or lost nearly half of it, and which one depended entirely on the platform.
Scope of Study
Measured on the OtterlyAI AI Search Index: 1,600 prompts across 16 US industry reports, run daily against seven engines (ChatGPT, Google AI Mode, Google AI Overviews, Claude, Perplexity, Gemini and Microsoft Copilot). All figures are the median of daily shares within the window, because a mean would be distorted by the ChatGPT volume swing described below.
August vs September: The social media category fell, but not evenly
Across all seven engines, September went to social platforms roughly one citation in twenty-three (4.311%), down from one in nineteen (5.146%) in August and one in seventeen (5.983%) in July. The social media category has lost a quarter of its share of AI Search in ten weeks.
The split underneath that is the finding:
| Platform | August | September | Aug to Sep |
|---|---|---|---|
| youtube.com | 2.189% | 1.842% | -16% |
| reddit.com | 1.761% | 1.714% | -3% |
| linkedin.com | 0.515% | 0.495% | -4% |
| facebook.com | 0.476% | 0.370% | -22% |
| instagram.com | 0.191% | 0.063% | -67% |
| tiktok.com | 0.037% | 0.023% | -37% |
| x.com | 0.000% | 0.001% | n/a |
| Other social | 0.060% | 0.073% | +21% |
Who benefited from the social media decline?
Mostly blogs, and personal sites (+3%), educational (+1%) and company owned pages, up 1% from an already dominant 58% share, which in actual citations outweighs every other increase combined.
Social platforms lost 8% of their share of AI Search between August and September and news and media lost 3%, but nothing absorbed it. The only meaningful gainer is Everything else moved less than half a percentage point. Due to the drastic decline in Reddit and YouTube AI citations, the whole Social media category dropped overall.
Source categories, August vs September
| Category | August | September | Change |
|---|---|---|---|
| Blogs and personal sites | 5.067% | 5.241% | +3% |
| Education | 4.060% | 4.111% | +1% |
| Brand, company owned | 57.263% | 57.954% | +1% |
| Government and NGO | 7.937% | 7.893% | -1% |
| News and media | 16.342% | 15.772% | -3% |
| Social media | 7.193% | 6.632% | -8% |
What the numbers mean
- Aug and Sep are shares: out of every 100 citations an engine made on a given day, how many pointed at that category. Median across the days in the month.
- Change is the difference between the two shares relative to August. Social media went from 7.193% to 6.632%, a drop of 0.561 points, which is 8% of 7.193.
What changed in September?
Within September the direction reverses for three of the six social media platforms:
- LinkedIn, Reddit and Facebook all end the month above where they started.
- YouTube, Instagram and TikTok all end below.
1. LinkedIn
A closer look at LinkedIn’s rise in September
LinkedIn was the platform that gained the most in September, and it gained everywhere except Google AI Overviews
| AI Search Engine | 1 September | 20 September | Change |
|---|---|---|---|
| Google AI Mode | 0.661% | 1.071% | +62% |
| ChatGPT | 0.171% | 0.284% | +66% |
| Perplexity | 0.784% | 1.187% | +51% |
| Microsoft Copilot | 0.282% | 0.322% | +14% |
| Claude | 0.145% | 0.152% | +5% |
| Google AI Overviews | 0.819% | 0.711% | -13% |
| Gemini | 0.000% | 0.000% | no citations |
Five of seven engines up, one down, one that does not cite LinkedIn at all. Perplexity is both the highest and among the fastest rising, which makes it the single most important engine for anyone whose content strategy runs through LinkedIn.
Set against the full quarter, the shape is clearer. ChatGPT’s LinkedIn share spiked on 8 August, collapsed with everything else in late August, and has been climbing back since.
LinkedIn by AI Search Engine: August vs September
- Perplexity (highest citer): 1.18% in July, stepped down to 0.57% between 29 July and 2 August, sat there six weeks, jumped back to 1.10% on 8 September. Ends at 1.075%, still 9% below July.
- Google AI Overviews: 0.853% to 0.739%, a gentle drift of -13%. No reaction to 8 August.
- Google AI Mode: 0.745% to 0.699%, -6%. Also ignored 8 August.
- Microsoft Copilot: fell 47% in the first week of July, 0.571% to 0.300%, then flat. 0.356% in September.
- ChatGPT: the biggest mover. 0.114% in July, quadrupled to 0.581% on 8 August, collapsed with its citation volume in late August, recovering since. 0.231% in September, up 103% in July off a tiny base.
- Claude: flat all quarter, 0.152% to 0.142%.
- Gemini: does not cite LinkedIn. Zero on 45 of 77 days, never above 0.03%.
2. Reddit
Reddit’s Quiet September
Reddit rose about 10% across September, from a 1.597% median in the first ten days to 1.751% in the last ten. The total is the least interesting thing about it, because it is two engines pulling up against two pulling down.
| AI Search Engine | 1 September | 20 September | Change |
|---|---|---|---|
| Google AI Overviews | 4.953% | 5.433% | +10% |
| Google AI Mode | 4.325% | 5.264% | +22% |
| Perplexity | 2.298% | 2.043% | -11% |
| Gemini | 1.423% | 1.295% | -9% |
| ChatGPT | 0.194% | 0.237% | +22% |
| Microsoft Copilot | 0.000% | 0.000% | no citations |
| Claude | 0.000% | 0.000% | no citations |
Reddit is a Google platform first. The two Google surfaces cite it more than every other engine combined, at 5.1% and 4.5% of their September citations, and both raised it through the month. Perplexity and Gemini moved the other way, and the two directions almost cancel.
Two engines do not use Reddit at all. Claude has not cited reddit.com on a single one of the 77 days we measured. Microsoft Copilot cites it on 23 of 77 and never above 0.05%. Reddit is a five-engine platform, and any Reddit strategy that assumes universal coverage is already wrong about two of the seven.
What this means for your GEO strategy: Reddit visibility is worth pursuing if your buyers use Google AI Overviews, AI Mode or Perplexity. It does nothing for you on Claude, and effectively nothing on Copilot.
Reddit by AI Search Engine: August vs September
The quarter view shows the one change that has not reversed. ChatGPT cited Reddit for 3.765% of its citations through July, more than any engine except Google AI Overviews. On 8 August it dropped to a fraction of that and has kept sliding: 0.227% in September, a fall of 94% against July. Every other engine carried on as if nothing had happened, which is what tells you this was a ChatGPT decision rather than anything Reddit did.
3. YouTube
YouTube’s Fall in September
YouTube was the platform that fell, and almost all of the fall is one engine changing its mind over two days.
| AI Search Engine | 1 September | 20 September | Change |
|---|---|---|---|
| Google AI Mode | 13.521% | 3.877% | -71% |
| Google AI Overviews | 8.322% | 6.509% | -22% |
| Gemini | 0.439% | 0.216% | -51% |
| ChatGPT | 0.131% | 0.148% | +13% |
| Claude | 0.071% | 0.143% | +102% |
| Perplexity | 0.056% | 0.196% | +250% |
| Microsoft Copilot | 0.035% | 0.094% | +167% |
Google AI Mode cited YouTube for 11.0% of its citations on 13 September. On 14 September that was 6.8%, on 15 September 3.1%, and every day from 16 September has landed between 3.4% and 3.9%. A 72% cut in 48 hours, with no recovery in the five days we have after it.
That single move carries the whole category. YouTube across all seven engines ran at a 1.941% median through the first ten days of September and 1.263% through the last ten, a fall of 35%. Weighting each engine by its citation volume, Google AI Mode accounts for 87% of that fall on its own and Google AI Overviews for another 17%. Every other engine moved the other way or not at all.
Read the three-digit gains as what they are. Perplexity, Copilot and Claude all show large percentage rises off bases under 0.1%. Perplexity going from 0.056% to 0.196% is roughly one citation in eighteen hundred becoming one in five hundred. It is a real direction and it is not a meaningful volume, and in Perplexity’s case it is a bounce off a floor: YouTube was 2.757% of Perplexity’s citations in July.
What this means for your GEO strategy: if video is your channel, your entire AI Search exposure now rests on Google AI Overviews. It is the only engine still citing YouTube at scale, and it is drifting down too.
YouTube by AI Search Engine: August vs September
The quarter explains why the September drop is so large. Google AI Mode spent July and August steadily increasing its use of YouTube, from 4.2% in July to 6.0% in late August, peaking at 14.1% on 29 August. It built the position up over two months and gave it all back in two days, ending below where it started. Google AI Overviews is the steady one: 6.8% in July, 7.2% in August, 7.0% in September, with the decline confined to the last three weeks.
Inside ChatGPT, September undid August
ChatGPT is where the quarter’s biggest swings happened, and September walked most of them back.
| Platform | 1 Jul to 7 August | 8 to 24 August | September |
|---|---|---|---|
| reddit.com | 3.765% | 0.553% | 0.227% |
| linkedin.com | 0.116% | 0.551% | 0.231% |
| youtube.com | 0.115% | 0.546% | 0.104% |
| All social | 4.164% | 1.921% | 0.683% |
Reddit was roughly thirty times larger than LinkedIn inside ChatGPT in July. On 8 August it fell 85% and LinkedIn rose, and the two met at effectively the same level. They have both since drifted down to around 0.23%.
The durable finding across all three months is the Reddit cut. It happened on one engine, it has not reversed, and it has deepened.
Final Conclusion
- LinkedIn, Reddit and Facebook rose through September.
- YouTube, Instagram and TikTok fell in September.
- However, overall, the social category still shrank -16% month over month.(August vs September)
- LinkedIn gained on five of seven engines, led by ChatGPT at 66% and Google AI Mode at 62%.
- ChatGPT’s citation volume recovered 65% in the first half of September, which explains most of its share movements and none of anyone else’s.
- Reddit is again the largest social source in AI Search, and ChatGPT is the one engine that no longer cites it.
- If you depend only on Reddit for AI visibility, treat ChatGPT as lost for now. It is down 94% against July and still falling.
Got a GEO experiment idea? Let’s collaborate
At OtterlyAI, we don’t write about AI Search from the sidelines. We test it. With the community, we run and update a public GEO Experimentation Tracker showing what we are running and what moved AI Search. If you are running your own GEO experiment, email rick.tousseyn@otterly.ai and we may feature it with your name attributed.
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