Share of search
Definition
Your share of the branded search volume in your category: searches for your brand, divided by searches for every brand in a set you define. It is often used as an early indicator of market share, because it tends to move before revenue does.
How it’s calculated
Define the category as a list of brand terms: yours, and every competitor a buyer would weigh you against. Pull monthly search volume for each from the same tool, add them up, and divide your volume by the total. The set must be agreed once, in writing, and then left alone; a set edited later can produce any trend you want.
What to watch for
The set is the first place it misleads: leave the market leader out and your share rises without anything changing in the market. Ask who is missing before admiring the line. Seasonality is the second: branded volume that climbs every autumn along with the whole category is a stable share dressed as growth, which is why the division matters and why the honest comparison is the same month a year earlier. And check the raw counts underneath: in a narrow category, monthly volumes run thin enough that one competitor’s campaign can swing the ratio, so read the line in quarters.
The question you ask
“Which brands are in the set, and when was it last changed?”