For the first time since its launch, OpenAI's ChatGPT has lost its absolute grip on the AI assistant market, with its share dipping below 50% by the end of May 2026. According to Sensor Tower's State of AI 2026 report, ChatGPT held 46.4% of the market, down from over 50% in January. Google's Gemini rose to 27.7%, while Anthropic's Claude reached 10.3%. The remaining share is scattered among assistants like xAI's Grok, Perplexity, DeepSeek, and Meta AI, each holding less than 5%.
The shift reflects a maturing market where users are increasingly willing to switch based on trust, integration capabilities, and specific use cases. Sensor Tower noted that OpenAI's February deal with the U.S. Department of Defense triggered a spike in ChatGPT uninstalls, highlighting how brand values can influence user loyalty. Gemini's momentum is largely attributed to its deep integration with Google's wider ecosystem—Android, Search, Chrome, and Workspace—while Claude has built a strong reputation for productivity and now leads with a 13% paid subscription conversion rate, the highest among competitors.
Monetization is taking center stage. OpenAI began serving ads to 17% of daily ChatGPT users by May, with retail and shopping among the top advertising categories. The app is evolving into a superapp with shopping integrations, sending referral traffic to retailers like Walmart and Target. Meanwhile, overall AI app downloads are projected to reach 2.3 billion in the first half of 2026, with in-app spending estimated at $4.2 billion, up sharply from $1.83 billion a year earlier. However, growth rates are decelerating, signaling a shift from pure user acquisition to revenue generation.
A notable highlight from the report is the user demographic data. Grok users are roughly four times more likely than the general population to be crypto traders, the widest skew measured. This is linked to Grok's integration with X, where crypto communities are highly active. Claude ranked second among crypto traders, while ChatGPT users barely exceeded the baseline. The report also recalled last fall's Alpha Arena contest, where Grok and Claude Sonnet generated real-money trading gains on Hyperliquid, while GPT-5 and Gemini 2.5 Pro lost over a quarter of their stakes.
ChatGPT still reached 1 billion monthly users in May, making it the fastest app to that milestone, ahead of TikTok, YouTube, and Instagram. But its dominance is no longer unquestioned. The competitive landscape now forces all players to balance capability with trust, distribution, and monetization strategy.
