ChatGPT's share of the global AI assistant market has dipped below 50% for the first time since its launch, as growing competition from Google's Gemini and Anthropic's Claude erodes the dominance OpenAI has held since it effectively created the modern AI chatbot category in late 2022.
According to analytics firm Sensor Tower's State of AI Report for 2026, ChatGPT commanded over 50% of AI assistant market share until January of this year, but by the end of May that figure had fallen to 46.4%. Gemini now holds 27.7% of the market, while Claude accounts for 10.3%. Other assistants including Grok, Perplexity, DeepSeek, and Meta AI each hold less than 5%.
ChatGPT remains the most popular AI assistant worldwide by a considerable margin, having recently crossed one billion monthly active users—the fastest any app has ever reached that milestone. Gemini has 662 million monthly users and Claude has 245 million.
Sensor Tower's report found that users are increasingly willing to switch between AI assistants, and that specific events appear to accelerate that behaviour. OpenAI's deal with the US Department of Defense in February triggered a measurable spike in uninstalls, suggesting that brand trust and alignment with user values matter alongside product quality.
Gemini's momentum is driven in large part by its integration into Google's wider ecosystem of tools. Claude, meanwhile, has built a strong reputation for productivity use cases and is closing in on ChatGPT's user retention rate. Notably, 13% of Anthropic's users are paying for a subscription plan, a conversion rate that leads the field.
In the first half of 2026, people are on pace to download nearly 2.3 billion AI apps and spend over $4.2 billion on them, compared with $1.83 billion in the same period of 2025. However, both download and spend growth rates have decelerated, an indicator that the market may be maturing even as absolute numbers continue to climb. Hours spent on AI apps are estimated to have risen from 17.2 billion in H1 2025 to roughly 36 billion in H1 2026, with the top three assistants accounting for 89% of total time spent.
Regionally, Asia recorded the first download decline of 3.3% in the first quarter of 2026, driven by dips in China and India. Despite leading globally in total downloads, Asia trails North America and Europe in in-app spending.
OpenAI began experimenting with advertising in ChatGPT in February. By May, an average of 17% of daily users were being served advertisements, with software and shopping the largest advertiser categories so far, followed by media and entertainment and food and dining.
