Is GEO Just Good SEO? What 1,899 AI Prompts Tell Us About Brand Visibility

A question is reshaping how marketing teams plan their budgets. If a brand ranks well on Google, does that automatically mean it will appear in AI-generated responses? The instinct is to say yes. If AI systems learn from the web, and good SEO means more web presence, then better SEO should translate into better AI visibility. We ran 1,899 AI prompts across 26 businesses on the Contxt network, spanning ChatGPT and Google AI Overview, to test that assumption. What we found challenges one of the most commonly held beliefs in digital marketing right now: that Generative Engine Optimisation is simply Search Engine Optimisation applied to a new interface. It is not. And the data makes this uncomfortably clear. What we measured The Contxt platform tracked 26 businesses across ChatGPT and Google AI Overview, running 838 unique prompt variations and completing 73 full tracker runs. Each prompt asked a realistic buying, research, or comparison question within a category. We then measured whether each brand was mentioned in the AI response, producing a mention rate per business per provider. The businesses span a range of sectors: consumer retail, industrial B2B manufacturing, logistics, outdoor apparel, pet supplies, healthcare products, entertainment venues, and specialist trade suppliers. They range from household names with significant SEO footprints to niche operators with modest web presences. The overall network mention rate across all businesses and prompts was 64.6%. But that average conceals a distribution that tells a far more interesting story. GEO visibility rates by sector type. Source: Contxt network data, 2025. Sector names anonymised. The headline finding: scale does not predict AI visibility Across the 26 businesses in the dataset, there is no consistent positive correlation between brand scale or organic search presence and AI visibility. Some of the largest, most recognisable brands in the dataset scored the lowest GEO rates. Some of the smallest, most nich