ChatGPT remains the world’s most widely used AI assistant, but its market share fell below 50% for the first time as users increasingly divided their activity among Google Gemini, Anthropic Claude, and other services. Sensor Tower estimated that ChatGPT’s share declined to 46.4% by the end of May 2026, compared with more than 50% in January.
ChatGPT had more than 1.1 billion monthly users, followed by Gemini with 662 million and Claude with 245 million, according to Sensor Tower’s State of AI Report for 2026. OpenAI separately reported more than 900 million weekly ChatGPT users and over 50 million consumer subscribers earlier this year.
Gemini and Claude Increase Their Shares
Gemini accounted for 27.7% of the AI assistant market at the end of May, while Claude held 10.3%. Grok, Perplexity, DeepSeek, and Meta AI each remained below 5%.
Gemini’s growth has been supported by its integration with Google’s products and services. Claude has attracted users focused on productivity and is approaching ChatGPT’s user-retention rate, according to the Sensor Tower report.
Users are also becoming more willing to move between assistants. Sensor Tower recorded a 295% daily increase in US ChatGPT uninstalls after OpenAI announced a deal with the US Department of Defense in February, compared with its average daily uninstall rate during the previous 30 days.
AI App Spending Continues to Rise
Consumers are on pace to download nearly 2.3 billion AI apps and spend more than $4.2 billion during the first half of 2026. Spending reached $1.83 billion during the same period in 2025, although the growth rates for both downloads and spending have slowed.
Time spent in AI apps is estimated to reach about 36 billion hours in the first half of 2026, up from 17.2 billion hours a year earlier. ChatGPT, Gemini, and Claude accounted for 89% of all time spent in AI assistant apps.
Asia recorded a 3.3% decline in AI app downloads during the first quarter, driven by decreases in China and India. The region still produced the most downloads, but North America and Europe generated more in-app spending.
Claude recorded the highest paid conversion rate, with 13% of its users subscribing to a paid plan. Average revenue per user also increased across AI assistant services as companies placed more focus on paid features.
ChatGPT Expands Ads and Shopping Features
OpenAI began testing ads in ChatGPT in February. By May, Sensor Tower estimated that 17% of its daily users were shown ads, with software and shopping companies forming the largest advertiser categories.
ChatGPT has also increased referral traffic to retailers such as Target, Walmart, and Costco through its shopping features. Amazon’s traffic from ChatGPT remained flat after the retailer blocked OpenAI’s web crawlers.
Retailers are developing their own shopping assistants as well. Walmart’s Spark has gained users, while Amazon shoppers who used Rufus spent more time in its app and completed purchases at higher rates than customers who did not use the assistant.
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