ChatGPT Falls Below 50% Market Share for the First Time as Gemini and Claude Surge
Sensor Tower's 2026 State of AI Report reveals ChatGPT slipped to 46.4% of AI chatbot monthly active users in May — the first time it's dropped under half. Gemini climbed to 27.7% and Claude reached 10.3%.
ChatGPT’s grip on the AI chatbot market just slipped below 50% for the first time. Sensor Tower’s State of AI Report 2026 puts OpenAI’s flagship at 46.4% of monthly active users across AI chat apps as of May 2026 — down from a dominant position that held above 50% for the better part of three years.
The raw numbers: ChatGPT at 1.1 billion MAU, Gemini at 662 million (27.7% share), and Claude at 245 million (10.3%). Grok, Perplexity, DeepSeek, and Meta AI each sit below 5%.
That’s not a rounding error. In absolute terms, Gemini nearly doubled its share since late 2025, and Claude’s audience grew faster than any other major Western AI product in the same window. Neither OpenAI nor Anthropic has commented on the data.
What’s driving the shift
The report highlights two structural changes. First, the consumer AI market has matured past the “just try the default” phase — users are now making deliberate product choices based on context. Gemini gets a boost from its tight integration with Android and Google Workspace. Claude benefits from a reputation for nuanced reasoning and a recent wave of enterprise adoption, plus the Claude Fable 5 release in early June, which outperformed on several coding and reasoning benchmarks.
Second, brand values are measurable acquisition drivers now. The Sensor Tower analysts flag that users are increasingly switching assistants not just for feature parity but because of perceived alignment with their professional identity or trust preferences. That’s a different problem for OpenAI than a feature gap — you can’t patch it with a model update.
The long tail matters
The combined “other” bucket — Grok, Perplexity, DeepSeek, Meta AI — holds around 15% of MAU between them. Small individually, but their collective growth indicates the market is fragmenting in a way that structural aggregation (Android defaults, ChatGPT habits) can’t fully counter.
Perplexity in particular has doubled MAU quarter-over-quarter by positioning itself as a search replacement rather than a chat tool. That’s a segment OpenAI is now competing in more directly with ChatGPT Search, but adoption curves haven’t shifted yet.
What this means for OpenAI
OpenAI is simultaneously preparing for a public offering — the company’s confidential IPO filing was reported in early June — and watching its most visible product lose market dominance for the first time. It doesn’t change the fundraising story immediately (revenue is still growing, GPT-4o and o3 Pro remain workhorses for enterprise contracts), but it adds pressure on the consumer retention side.
Gemini’s trajectory is the more interesting benchmark. Google is distributing AI through the largest mobile OS on the planet. If Android 17 Gemini integrations drive even a modest shift in default usage, Sensor Tower’s next quarterly report could show Gemini closing to within 10 points of ChatGPT.
The race for the top spot is no longer a foregone conclusion.