ChatGPT no longer holds the majority of the AI market—a historic first.

The figure that crystallizes it all is May 2026’s: 46.4% of the consumer AI assistant market for ChatGPT, measured across twenty-five markets. In March, it fell below the 50% mark for the first time since the service launched in November 2022. OpenAI remains number one (1.1 billion monthly users, which is no small thing), but the trend has not reversed since.Gemini now accounts for 27.7% of the market, with 662 million users. Claude has reached 10.3%, with 245 million users, and one detail is worth pausing on: its conversion rate to paid plans is 13%, the highest in the entire sector, which says something about the quality of its user base rather than its size.

How trust in OpenAI began to crack

In the timeline of ChatGPT’s decline, an identifiable starting point emerges. In February 2026, OpenAI signed a cooperation agreement with the Pentagon covering the use of its models for military purposes—a decision that crystallized latent tensions within its user base and prompted internal departures. The following weeks saw a measurable spike in uninstallations in the sector’s behavioral data. This is not the only factor behind the drift, and ChatGPT remains far ahead in absolute volume, but it is a clearly identifiable trigger in a sector where trust is built over years and lost within a few news cycles.

Over time, users who switch away from ChatGPT tend not to return: the sector’s retention data show no significant return to the service after an uninstallation. What initially looked like a cyclical decline is beginning to take on the hallmarks of a structural trend, especially since the alternatives have markedly improved in quality over the same period.

The DMA ambushes Gemini

Gemini's rise to 27.7% cannot be explained solely by the model's performance. Let's not forget that the assistant comes preinstalled with Android, and that Google is actively promoting it in every corner of its mobile operating system. Europe, which is closely monitoring this trend, is also gearing up its DMA to give users a more informed choice. A boon for OpenAI!

In France and Europe, diversification goes beyond just the OpenAI-Google head-to-head. European-hosted alternatives, led by Mistral Vibe, are gaining credibility for professional use against a backdrop of growing distrust of American players when it comes to data sovereignty. ChatGPT's decline makes room on a market that is only just beginning to truly take shape.

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Source: Sensor Tower via TechCrunch