Share of AI Search is the share a brand holds of the answers to a fixed prompt set, measured as mentions and citations, compared with competitors on the same prompts and viewed over time. The guiding question: is my presence in the answers to the relevant questions growing compared with my competitors? It is the AI counterpart of Share of Search, which in SEO measures the share of a keyword set.
How does Share of AI Search work?
The basis is the prompt set, which is queried regularly across all important AI systems. For each answer, the brands mentioned and the sources cited are recorded: your own and those of competitors. The share is the portion your own brand holds of all recorded mentions or citations. It can be analysed per category of the prompt set, per system and over time.
Measuring success in AI search thus differs fundamentally from classic SEO:
| Classic SEO | AI search | |
|---|---|---|
| Metrics | Impressions, clicks, ranking position, Share of Search, AI Overview Citation Rate | AI visibility / Citation Rate, traffic via LLMs, Share of AI Search, Sentiment, LLM crawler requests |
| Interpretation | Ideally, impressions rise; traffic stagnates or falls for existing content | It is about the basic visibility of the brand in AI interfaces, not about traffic from this channel |
| Goal | Defend or expand your own slice of a shrinking pie | Starting from a baseline measurement, increase Share of AI Search relative to competitors |
Why does Share of AI Search matter for AI visibility?
Because absolute values mean nothing in AI answers. A Mention Rate of 40% is good if the strongest competitor is at 25%, and bad if it is at 80%. And because the channel delivers no clicks (Zero-Click): the success of AI search is measured not in traffic but in presence. Branding logic, not performance marketing.
What does this mean for your website?
Start with a baseline measurement across your prompt set in all relevant systems, including competitors. Define the goal as a share, not a position. Analyse the share per category: a high share on research questions and a low one on comparison and trust questions shows where the work lies. And stay critical: presence in the wrong answer, on the wrong topic, with negative sentiment, does not count.