ChatGPT loses half its share in Spain: your GEO cannot bet on a single horse

For three years I have heard that ChatGPT is synonymous with AI, and I just ran into a Sensor Tower chart that dismantles that idea with data from Spain. In May 2023, ChatGPT held 90% of unique users of AI assistants. By May 2026 it hovers around 45%. Half its share, gone in three years. And not because ChatGPT lost users, but because the market grew underneath it while almost nobody was telling that story.

What strikes me most is who captured that growth. Google Gemini went from a token 3% to almost 28%: the "latecomer" is now the clear number two, and with Android, Search and Workspace as distribution channels, that does not look like a coincidence to me. Claude was flat for years and in recent months draws a clear, sustained climb. Grok has been scaling quietly since 2025 with X's distribution pushing behind it. And DeepSeek's brutal spike in January 2025 was the R1 launch: half the world tried it out of curiosity and it deflated as fast as it rose.

Why does this matter to me beyond the chart? Because if your AI visibility strategy (GEO, content, brand) is still designed "so ChatGPT recommends me", you are optimizing for 45% of the market, not 100%. And there is a second problem I see every week in audits: the user who asks about your brand in Gemini, Claude or Meta AI does not see the same answer, the same sources or the same "truth" as the one who asks ChatGPT. Each assistant builds its own story about you.

The question I ask myself with every client is no longer whether they show up in ChatGPT. It is how many assistants they exist in and what each one says about them. If your GEO still bets everything on one horse, this chart is the warning.