Share of Model is the post-Citation-Share metric — tracking a brand's presence and prominence across multiple large language models simultaneously. Citation Share measures within a single engine (ChatGPT, Claude, Perplexity, etc.). Share of Model measures across all major engines at once, providing a consolidated view of AI visibility.
Calculation: A brand appears in answers from ChatGPT (12% citation share), Claude (14%), Perplexity (10%), Gemini (9%), and Google AI Overviews (11%). The combined average — Share of Model — is 11.2%. This is the headline metric for board-level AI Communications reporting: "Our share of model is 11.2% across all major engines, up from 8.7% last quarter."
Share of Model smooths out single-engine volatility. A product launch might spike a brand's ChatGPT citations but not move Perplexity; measuring only ChatGPT creates noise. Share of Model captures the consolidated trend. It also flags uneven distribution: if a brand owns 18% of Perplexity but only 6% of Claude, Share of Model will reveal skew that demands investigation.
In strategy and measurement, Share of Model is the executive summary. Citation Share by engine is the detail layer. A strong AI Communications program targets consistency across all five major engines rather than concentration in one. Share of Model is how you report that balance to stakeholders and track progress toward multi-engine dominance.




