Citation concentration is the pattern by which a small number of highly-cited domains account for a disproportionate share of citations on a given platform.
Citation concentration is the pattern by which a small number of highly-cited domains account for a disproportionate share of citations on a given platform. Wikipedia accounts for 7.8% of all ChatGPT citations. YouTube leads Google AI Overviews at approximately 10%. Only 14% of the top 50 cited sources are shared across ChatGPT, Perplexity, and Google AI Overviews.
Citation concentration has two implications. First, the platforms do not share a citation footprint — optimizing for one does not transfer to the others. Second, the dominant cited domains on each platform are structurally embedded in ways that reflect the platform’s underlying index and parametric layer. Brands cannot displace these; they can only compete within the long tail.