Semrush's study of 150,000 AI citations found Reddit is the single most-referenced domain at 40.1 percent of all LLM references, ahead of Wikipedia at 26.3 percent and YouTube at 23.5 percent. The same finding was reported independently by Search Engine Land. Engines lean on user-generated content and encyclopedias because they capture first-hand discussion and dense natural-language phrasing, and because a polished brand blog reads as marketing and gets discounted. This is the mechanical reason a brand's own domain is rarely the cited source on a category head term.
Inside a single engine the concentration is sharper still. Profound's analysis of 680 million citations found Wikipedia is 47.9 percent of ChatGPT's top-10 sources while Reddit is 46.7 percent of Perplexity's top-10, so the two leading engines lean on almost opposite anchors. Profound also found 80.41 percent of ChatGPT's cited URLs end in .com, so commercial third parties are cited heavily, just not the brand under test; the slots go to aggregators, review platforms, and competitors on the category question.
Semrush's Ghost Citations study, across 3,981 domain appearances, 115 prompts, 14 countries, and 4 engines, adds the sharpest version of the problem: 61.7 percent of AI citations are ghost citations, where the engine uses a page as a source without naming any brand at all, and only 13.2 percent of appearances included both a citation link and a brand mention. Gemini names a brand 83.7 percent of the time but cites a source only 21.4 percent, while ChatGPT cites a source 87 percent of the time but names the brand only 20.7 percent. The engine can lean on your content and still leave your name out of the answer.
The over-reading to avoid is that a brand should spam Reddit. The signal an engine rewards is a genuine, upvoted, answer-shaped discussion a retrieval system can lift as a self-contained response, which is the opposite of a promotional thread. The lesson is not to abandon owned content but to earn presence inside the sources the engine already consults for the category, which is what the levers section below is about.