OpenAI’s ChatGPT has lost its majority share of the global AI assistant market for the first time as competition from rival platforms continues to intensify, according to Sensor Tower’s State of AI Report 2026.
The report shows that ChatGPT remains the world’s most widely used AI assistant, with more than 1.1 billion monthly users. However, its market share declined to 46.4% by the end of May, down from more than 50% in January.
Google’s Gemini emerged as the biggest challenger, increasing its share to 27.7%, while Anthropic’s Claude reached 10.3%. Other AI assistants, including Grok, Perplexity, DeepSeek and Meta AI, each accounted for less than 5% of the market.
Despite the decline in market share, ChatGPT continues to record significant growth. Sensor Tower recently reported that it became the fastest application to reach one billion monthly users. OpenAI last disclosed that ChatGPT had 900 million weekly active users as of February.
The report noted that users are becoming increasingly willing to switch between AI assistants, with factors beyond product features influencing adoption. According to Sensor Tower, OpenAI’s partnership with the U.S. Department of Defense earlier this year triggered a measurable increase in app uninstalls, suggesting that brand perception and corporate decisions can affect user loyalty.
Gemini’s growth has been largely driven by its integration across Google’s ecosystem of products and services, while Claude has gained traction among productivity-focused users and is narrowing the gap with ChatGPT in user retention metrics.
The AI app market also continues to expand rapidly. Sensor Tower estimates that users will download nearly 2.3 billion AI applications and spend more than $4.2 billion on them during the first half of 2026, compared with $1.83 billion during the same period in 2025.
While spending and downloads continue to grow, the report noted that growth rates are slowing, indicating that the market may be gradually maturing.
Regionally, Asia recorded its first decline in AI app downloads, falling by 3.3% during the first quarter of 2026 due to weaker demand in China and India. However, the region remains the largest market globally by total downloads.
In contrast, North America and Europe continue to lead in user spending on AI applications. Sensor Tower said U.S. users are increasingly adopting AI assistants for productivity purposes and are more likely to pay for premium features.
Anthropic’s Claude recorded the highest subscription conversion rate among major AI assistants, with 13% of users paying for premium plans.
The report also estimates that total time spent on AI applications will increase from 17.2 billion hours in the first half of 2025 to approximately 36 billion hours during the same period in 2026.
According to the report, ChatGPT, Gemini and Claude collectively account for 89% of all time spent on AI assistant applications, underscoring their dominance in a rapidly evolving market.
