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Stock Markets June 2, 2026 06:25 PM

ChatGPT Tops 1 Billion Monthly Active Users, Sensor Tower Data Shows

OpenAI’s app becomes the fastest to hit 1 billion MAUs as competition from Anthropic intensifies and both companies move toward IPO plans

By Sofia Navarro

OpenAI’s ChatGPT surpassed 1 billion global monthly active app users in May, becoming the fastest application to reach that milestone, according to market intelligence from Sensor Tower. The milestone arrives amid rising competition from Anthropic’s Claude, which has shown rapid year-over-year user growth, and as both companies take steps toward potential U.S. initial public offerings.

ChatGPT Tops 1 Billion Monthly Active Users, Sensor Tower Data Shows

Key Points

  • ChatGPT reached 1 billion global monthly active users in May, becoming the fastest app to reach that milestone, according to Sensor Tower.
  • Anthropic’s Claude has 56 million global MAUs as of the second quarter to date and exhibited roughly 640% year-over-year MAU growth, outpacing ChatGPT’s 62% growth.
  • Both Anthropic and OpenAI are moving toward U.S. IPO filings, with Anthropic confidentially filing on Monday and OpenAI preparing to file in the coming weeks; competition between the two is already having measurable effects on user engagement.

OpenAI’s ChatGPT has exceeded 1 billion global monthly active app users, a pace Sensor Tower says is the fastest on record for any app. The firm reported that ChatGPT reached the 1 billion monthly active users milestone in May, roughly three years after its launch, outpacing the adoption timelines of apps such as Google Maps, TikTok, Instagram and YouTube.

Sensor Tower’s analysis also highlights the competitive dynamics between ChatGPT and Anthropic’s Claude. The data indicate that U.S. users who installed Claude in the first quarter of 2026 spent 5% less time on ChatGPT one month after installing Claude, compared with their average ChatGPT usage during the eight months prior to installation.

Corporate financing moves are occurring alongside user shifts. Anthropic confidentially filed for a U.S. initial public offering on Monday. OpenAI is likewise preparing to file for an IPO in the coming weeks.

Usage trends through the second quarter to date show Claude with 56 million global monthly active app users. Sensor Tower noted that Claude’s year-over-year MAU growth is approximately 640%, a rate that substantially outpaces ChatGPT’s 62% year-over-year MAU growth.

These figures illustrate both the scale ChatGPT has achieved and the rapid user expansion Anthropic is experiencing. The data point to a market in which a dominant incumbent has reached a major user milestone while a competitor is gaining share quickly, and both companies are taking steps that could bring them to public markets.

Details

  • ChatGPT reached 1 billion monthly active users in May, roughly three years after launch, per Sensor Tower.
  • U.S. users who installed Claude in Q1 2026 reduced their ChatGPT usage by 5% one month after installation, relative to their prior eight-month average.
  • Anthropic confidentially filed for a U.S. IPO on Monday; OpenAI is preparing for an IPO filing in the coming weeks.
  • As of the second quarter to date, Claude recorded 56 million global MAUs and about 640% year-over-year MAU growth, versus ChatGPT’s 62% year-over-year MAU growth.

Contextual note

The metrics above come from Sensor Tower estimates and quantify both absolute scale and growth velocity for these AI chat applications. They show a combination of rapid overall market expansion and direct user-level displacement where Claude installations correlate with a modest decline in ChatGPT usage among affected U.S. users.

Risks

  • Competition risk: Installation of Anthropic’s Claude correlated with a 5% decline in ChatGPT usage among U.S. users one month after installation, indicating potential user displacement that could affect engagement metrics and monetization - impacts are most relevant to AI software and consumer apps sectors.
  • Execution and market-entry risk: Both companies are pursuing IPO processes, creating timing and execution uncertainty for investors and capital markets as filings progress - this primarily affects capital markets and technology sector investors.
  • Growth sustainability risk: While ChatGPT has reached large scale, Claude’s substantially higher year-over-year growth rate highlights uncertainty about which platform will sustain faster user growth over time - relevant to technology, AI services, and app-based monetization strategies.

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