Bottom line: ChatGPT retains the most users but must cede market share to Gemini (27.7%) and Claude (10.3%), as the industry shifts from user acquisition to monetization.
OpenAI loses absolute market leadership in AI assistants. ChatGPT’s market share declined from over 50 percent in January to 46.4 percent by end of May 2026, while Google Gemini and Anthropic Claude gained ground.
Sensor Tower’s State of AI Report 2026 documents a significant shift in the competition for AI assistants. ChatGPT lost over 3.6 percentage points of market share between January and May 2026, dropping from over 50 to 46.4 percent. In the same period, the competition consolidated: Google Gemini reached 27.7 percent market share, Anthropic Claude 10.3 percent. Other providers such as Grok, Perplexity, DeepSeek, and Meta AI each held under 5 percent.