How to define it
Pick the queries that describe your category, including generic and competitor queries, then measure your share of impressions or of top placement across them. Share of impressions from Brand Analytics Search Query Performance is the native starting point. Third party digital shelf tools add competitor rankings and placement data.
Organic and paid
Report the two separately. Organic share reflects catalogue quality, reviews and availability. Paid share reflects Sponsored Products and Sponsored Brands investment. A rising paid share on a flat organic share is a rented position that disappears when spend stops.
Why it is an executive metric
Share of search turns the conversation about media spend from cost per click into position in the category. It also bridges to the digital shelf view across retailers and AI assistants. Put it next to TACoS in the JBP review so spend is judged by what it buys in visibility.