OpenAI built the fastest app in history to reach one billion monthly users, and it is now watching that dominance erode in real time. According to Sensor Tower’s State of AI Report for 2026, reported by TechCrunch, ChatGPT’s share of the AI assistant market fell to 46.4% by the end of May, crossing below 50% for the first time since the product launched in late 2022.
The significance of that threshold is not cosmetic. A market leader above 50% sets reference pricing, anchors integrations, and defines the default choice for enterprise procurement. One below 50% must compete on terms. That is a different business.
The runner-up positions are now meaningful. Gemini holds 27.7% of the market, with 662 million monthly users, a figure built almost entirely on Google’s distribution machine: Android preinstalls, Workspace embeds, and Search tie-ins. Anthropic’s Claude sits at 10.3% with 245 million monthly users, a smaller absolute number but arguably a sharper revenue profile. Thirteen percent of Claude’s user base pays for a subscription, a conversion rate that leads the field and suggests Anthropic is building a smaller, more monetizable base rather than chasing raw volume.
Every other assistant, including Grok, Perplexity, DeepSeek, and Meta AI, commands less than 5% individually. The top three control 89% of time spent on AI assistant apps. That concentration means the structural story is really a two-player race between OpenAI and Google, with Anthropic as the most credible third option.
Sensor Tower’s data also tracks what drives switching behavior, and the findings are more useful than any feature comparison. OpenAI’s February deal with the U.S. Department of Defense produced a measurable spike in ChatGPT uninstalls. Users did not migrate because a competitor’s model scored higher on a benchmark. They migrated because brand trust broke. That dynamic is new for this category and suggests that AI assistants, once considered purely utility products, are accumulating political and reputational surfaces that can move market share as quickly as a product release.
The spending numbers add a further complication for OpenAI. Users are on pace to spend roughly 4.2 billion dollars on AI apps in the first half of 2026, up from 1.83 billion in the same period last year. That is real monetization traction across the industry. But both download and spend growth rates are decelerating, which points to a market entering a consolidation phase rather than a pure growth phase. OpenAI, facing that consolidation with a retreating share number, has begun scaling ads inside ChatGPT. By May, 17% of daily users were being served ads, with software and shopping as the leading advertiser categories. The company is building a media business on top of an assistant product at exactly the moment its assistant monopoly is ending.
Asia, which leads the world in total AI app downloads, recorded a 3.3% download decline in Q1 2026, driven by drops in China and India. That matters because Asia’s monetization per user trails North America and Europe significantly. If the high-spending regions are where margin gets built, and if those regions are where Gemini and Claude are gaining fastest, OpenAI’s advertising pivot may be addressing the wrong problem.
The 46.4% figure is a single data point, not a trend verdict. ChatGPT still has more than twice the monthly users of its nearest competitor. But the structural conditions that produced near-monopoly share, a two-year head start and no credible alternative, are gone. Builders evaluating which assistant API to anchor their products to in the next procurement cycle should treat this number as confirmation that the default assumption has changed.
Reported by TechCrunch on 2026-06-16.
