In 2026, the traditional “Marketing Funnel” is dead. With the rise of AI search agents and a 25% drop in traditional search volume, looking at your sales data alone is like driving a car while only looking in the rearview mirror.

If you want to know who will win the market six months from now, you need to stop obsessing over Market Share and start tracking Share of Search (SoS).

Why Market Share is a “Lagging” Metric

Market share tells you who won yesterday. By the time a brand’s market share drops, the damage was done months ago in the minds of consumers.

Share of Search is a leading indicator. It measures the “mental availability” of your brand. When people search for your brand by name, they are expressing the highest form of intent.

The 83% Rule: Research by effectiveness expert Les Binet shows an 83% correlation between Share of Search and eventual Market Share. In categories like automotive, SoS can predict sales shifts up to 12 months in advance.

How to Calculate Share of Search

You don’t need expensive enterprise software to do this. You just need a search tool (like Google Trends or Ahrefs) and this simple formula:

Formula:

The “Future Growth” Table

Frequently Asked Questions

What is “Excess Share of Search” (ESoS)?

This is the “Golden Ratio.” If your Share of Search is higher than your current Market Share, your brand is likely to grow. If it’s lower, you are losing “mindshare” and your sales will eventually follow that downward trend.

Does AI search (ChatGPT, Gemini) affect this?

Yes. In 2026, “Share of Model” or “Citation Depth” is becoming just as important. If AI agents aren’t “searching” for you to provide answers, you’re invisible. Tracking branded search volume remains the best proxy for how many humans are actually interested in you.

Can a small brand beat a giant using this?

Absolutely. Small brands often have a higher SoS relative to their size because they have “cult” followings. If a small brand’s SoS starts to climb, it’s a signal to investors that a market disruption is coming.