June 16, 2026 OpenAI’s ChatGPT remains the world’s most popular AI assistant, but its global market share has fallen below 50 per cent for the first time. New data from Sensor Tower’s State of AI Report 2026 shows that ChatGPT’s share declined to 46.4 per cent by the end of May as rivals including Google’s Gemini and Anthropic’s Claude continued to gain users.
Despite the decline in market share, ChatGPT still leads the industry with more than 1.1 billion monthly users. Gemini ranks second with 662 million monthly users, while Claude has reached 245 million users.
Until January, ChatGPT controlled more than half of the AI assistant market. By May, Gemini had grown to a 27.7 per cent share, while Claude reached 10.3 per cent. Other competitors, including Grok, Perplexity, DeepSeek, and Meta AI, each accounted for less than 5 per cent.
Sensor Tower found that users are becoming more willing to switch between AI assistants. The report noted that specific events can influence user behavior, citing a measurable increase in ChatGPT uninstalls following OpenAI’s Department of Defense partnership announcement in February.
Gemini’s growth has been supported by its integration across Google’s ecosystem, while Claude has built momentum through productivity-focused use cases. Anthropic’s assistant is also approaching ChatGPT’s user-retention levels.
The broader AI app market continues to expand. Sensor Tower estimates that consumers are on track to download nearly 2.3 billion AI apps and spend more than $4.2 billion on them during the first half of 2026. That compares with $1.83 billion in spending during the same period in 2025.
While downloads and spending continue to rise, growth rates have slowed, suggesting the market may be entering a more mature phase. Regional trends show Asia experienced its first decline in AI app downloads, falling 3.3 per cent in the first quarter of 2026 due to lower activity in China and India. However, North America and Europe continue to generate higher levels of in-app spending.
Claude stood out in monetization metrics. Sensor Tower estimates that 13 per cent of Anthropic users pay for subscriptions, the highest conversion rate among major AI assistants.
Usage is also increasing rapidly. Total time spent on AI apps is projected to reach roughly 36 billion hours in the first half of 2026, up from 17.2 billion hours a year earlier. ChatGPT, Gemini, and Claude together account for 89 per cent of all time spent in AI assistant apps.
The report also highlighted growing efforts to monetize AI platforms through advertising and commerce. OpenAI began testing ads in ChatGPT in February, with 17 per cent of daily users seeing advertisements by May. Software, shopping, media, entertainment, and food brands were among the largest advertising categories.
