What is Model Share?

Model Share is the percentage of AI-generated answers, within a defined prompt set, in which a brand is mentioned. It is the generative-search analogue of share of voice, measured across ChatGPT, Gemini, Perplexity, Claude and Copilot. The metric exists because buyers increasingly stop at the AI answer rather than clicking through to a ranked list, so a brand can hold position one in Google and still be absent from the response a buyer actually reads. Measuring it requires running a category's real buyer prompts against each model on a schedule and recording three things: whether the brand was named, how it was described, and which sources the model cited. The third is what makes the metric actionable — it identifies the specific page, review or discussion that moved visibility, rather than merely reporting that visibility moved.