ChatGPT’s market share slips below 50% for first time

ChatGPT's share of the AI assistant market has fallen below 50% for the first time, dropping to 46.4% in May as users increasingly adopt alternatives from Google, Anthropic, and xAI, according to analytics firm Sensor Tower [1]. The OpenAI chatbot still leads globally with over 1.1 billion monthly users, followed by Google's Gemini at 662 million and Anthropic's Claude at 245 million [1]. Gemini now holds 27.7% of the market, while Claude has reached 10.3% [1]. Other assistants, including xAI's Grok, Perplexity, DeepSeek, and Meta AI, each command less than 5% [1]. Sensor Tower's State of AI Report for 2026 found that users are increasingly willing to switch between assistants [1]. OpenAI's deal with the U.S. Department of Defense in February triggered a measurable spike in uninstalls, with Sensor Tower noting that "brand trust and values alignment matter to users, not just features" [1]. The dispute between Anthropic and the Department of Defense, which began in January 2026 over military and domestic surveillance uses of its products, has drawn attention to how AI companies navigate government contracts [11]. Anthropic, founded in 2021 by former OpenAI employees Daniela and Dario Amodei, had an estimated valuation of $965 billion in May 2026, making it the most valuable pure-play AI company in the world [10]. The company's Claude has gained a reputation for productivity use cases and is closing in on ChatGPT's user-retention rate [1]. Thirteen percent of Anthropic's users pay for a subscription plan, a conversion rate that leads the field [1]. The broader AI app market is shifting from growth toward monetization. Sensor Tower estimates users will download nearly 2.3 billion AI apps and spend over $4.2 billion on them in the first half of 2026, up from $1.83 billion in spending during the same period in 2025 [1]. Hours spent on AI apps are projected to reach roughly 36 billion in H1 2026, compared to 17.2 billion in H1 2025 [1]. However, both download and spend growth rates have decelerated, suggesting the market may be maturing [1]. Asia recorded its first quarterly download decline of 3.3% in Q1 2026, driven by dips in China and India [1]. Despite leading globally in total downloads, the region trails North America and Europe in in-app spending [1]. OpenAI began experimenting with ads in ChatGPT in February and has scaled the number gradually [1]. By May, an average of 17% of daily users were being served ads [1]. Software and shopping represent the largest advertiser categories, followed by media and entertainment and food and dining [1]. As ChatGPT deepens shopping integrations, it is sending referral traffic to retailers including Target, Walmart, and Costco, while Amazon, which has blocked ChatGPT's web crawlers, has seen stagnant referral traffic from the platform [1]. Walmart's AI assistant Spark has gained ground, while Amazon's Rufus has seen flat user growth [1].