ChatGPT market share falls below 50% as Gemini rises

ChatGPT's market share slipped below 50% for the first time, falling to 46.4% by the end of May as users migrate to rivals such as Google’s Gemini (27.7%) and Anthropic’s Claude (10.3%), Sensor Tower’s State of AI Report for 2026 shows. The three largest assistants still dominate usage but the competitive balance is shifting.

How big was ChatGPT’s decline and who picked up users?

ChatGPT held more than 50% market share in January but dropped to 46.4% by the end of May, while Gemini rose to 27.7% and Claude to 10.3%. ChatGPT remains the most-used assistant with over 1.1 billion monthly users, followed by Gemini at 662 million and Claude at 245 million; other assistants including Grok, Perplexity, DeepSeek and Meta AI each have less than 5% market share.

The decline accelerated around specific events that prompted switching behavior. Sensor Tower identified OpenAI’s February deal with the U.S. Department of Defense as triggering a measurable spike in uninstalls from ChatGPT, an example of how trust and values can influence retention as much as features.

How are usage and monetization trends shifting across AI apps?

Users are downloading and spending on AI apps at growing absolute levels even as growth rates slow: Sensor Tower estimates nearly 2.3 billion AI app downloads and over $4.2 billion in spending in H1 2026, up from $1.83 billion in H1 2025. Hours spent on AI apps are estimated to rise from 17.2 billion in H1 2025 to roughly 36 billion in H1 2026, with the top three assistants capturing 89% of time spent on assistant apps.

Regional patterns vary. Asia led total downloads but recorded a 3.3% download decline in Q1 2026 driven by China and India, and it lags North America and Europe on in-app spending. Conversion to paid tiers is a focal metric: 13% of Anthropic’s users are paying for a subscription plan, a leading conversion rate Sensor Tower highlights.

ChatGPT has begun experimenting with ads. By May, an average of 17% of daily ChatGPT users were being served ads, and software and shopping were the largest advertiser categories so far. ChatGPT’s shopping integrations are already sending referral traffic to retailers like Target, Walmart and Costco, while Amazon — which has blocked ChatGPT’s web crawlers — has seen stagnant referral traffic from the platform.

Why does this shift matter?

Market-share movement away from a single dominant assistant signals that user loyalty in AI is more fluid than in many mature app categories. Rising alternatives that integrate with larger ecosystems or emphasize specific use cases can erode a lead rapidly: Gemini’s momentum is linked to Google ecosystem integration, while Claude has gained traction on productivity and retention. The combination of rising ad exposure (17% of daily users seeing ads) and stronger subscription conversion for some rivals (13% of Claude users paying) shows the market is moving from pure growth toward monetization strategies that could reshape which players are sustainable.

Shifts in regional downloads and the disparity between download leadership and spending also shape where companies will invest in paid features. The spike in uninstalls after OpenAI’s DoD deal demonstrates reputational risks that can have immediate product-level effects on retention.

What to watch

Watch monthly-user and market-share updates for the next Sensor Tower release to see if ChatGPT stabilizes or continues to lose share from 46.4%. Track two commercial signals: conversion rates to paid plans (Anthropic’s 13% rate is an early benchmark) and the share of daily users served ads (ChatGPT hit 17% by May). Also monitor referral traffic trends as assistants deepen shopping integrations with retailers like Walmart, Target and Costco.