Developed by Les Binet in 2012, Share of Search treats branded search volume as a proxy for brand consideration — the theory being that when people are close to a purchase decision, they search for brand names, and the mix of which brands they search for reflects the underlying shift in consideration before it shows up in actual sales or market-share data.
The distinction that matters is relative versus absolute. Tracking your own branded search volume over time — already covered separately under Brand Search — tells you whether interest in your brand is rising or falling in isolation. Share of Search asks a different, more useful question: rising against what baseline? A brand whose search volume grows 20% means very little if the category's total search volume also grew 20% — its actual share of consideration hasn't moved at all.
The reason this gets attention beyond a vanity metric is Binet's original finding: Share of Search movements can precede market-share shifts by up to a year, making it one of the few available leading indicators for brand health that doesn't require expensive, slow-to-arrive market research.
Formula
Share of Search (%) = (Your Brand's Search Volume ÷ Total Search Volume for All Named Competitors) × 100
Pull indexed search-volume data (Google Trends or a keyword-volume tool) for your brand name and every named direct competitor over the same time window, then divide your volume by the sum of all of them — not by total category search volume including generic terms.
Why Share of Search matters
It's a leading indicator that doesn't require waiting for a market-research report or a sales cycle to complete — a shift in Share of Search this quarter can be the earliest available signal that a market-share shift is coming, in either direction.
Reading a Share of Search trend line correctly
A challenger brand tracks its search volume against three named competitors over 12 months. Its own branded search grew 15% year over year — a number that would read as clear success in isolation. But the category's combined competitor search volume grew 22% over the same period, meaning the brand's Share of Search actually fell from 24% to 21%. Absolute search growth looked like momentum; relative Share of Search revealed the brand was quietly losing ground to competitors growing faster, a signal that wouldn't have shown up by tracking branded search volume alone.
Common mistakes
Tracking absolute branded search instead of the relative share
Rising branded search volume in isolation says nothing about competitive position if the whole category is growing. Share of Search only means something calculated against named competitors' volume, not as a standalone trend line.
Including generic category terms in the denominator
The denominator is the sum of named competitor brand searches, not total category search volume including generic, non-branded terms — mixing the two produces a number that isn't Share of Search and isn't comparable to how the metric is used in the research it's drawn from.
Reading a single snapshot instead of a trend
One month's Share of Search figure is close to meaningless on its own. The predictive value Binet identified comes from tracking the trend over time and watching for it to move ahead of market-share data, not from a single point-in-time comparison.
Omitting a real competitor because it's inconvenient
Leaving a genuine competitor out of the denominator to make the ratio look better defeats the purpose — the metric's value depends on an honest, complete competitive set, including competitors gaining ground uncomfortably fast.
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