According to Sensor Tower's latest 2026 AI Industry Report, ChatGPT's global market share in AI assistant monthly active users (MAU) dropped to 46.4% as of May 2026, marking the first time since its launch over three years ago that the service has fallen below the 50% threshold.
Despite the decline, ChatGPT retains its global leadership position with approximately 1.1 billion monthly active users. Google Gemini ranks second with 662 million users and a 27.7% market share, while Anthropic's Claude comes third with 245 million users and a 10.3% share. Other players including Grok, Perplexity, DeepSeek, and Meta AI each hold less than 5% market share. The market structure has shifted from ChatGPT's previous dominance to a three-way competitive landscape.