ChatGPT just lost its majority for the first time since it launched and the AI race is officially a multi-horse situation.
Sensor Tower’s State of AI Report for 2026 dropped this week with a number that would’ve sounded impossible a year ago. ChatGPT’s global market share fell to 46.4% by the end of May, dipping below 50% for the first time since OpenAI released the chatbot back in late 2022. For context, ChatGPT held over 50% market share as recently as January. That’s a pretty fast slide for a product that still has over 1.1 billion monthly users.
So what actually happened?
The Challengers Got Real
Gemini is now sitting at 27.7% market share with 662 million monthly users, and Claude is at 10.3% with 245 million. Grok, Perplexity, DeepSeek, and Meta AI are all under 5% individually, but collectively they’re chipping away at the edges too.
To be clear, ChatGPT is still the biggest AI assistant on the planet by a wide margin. It became the fastest app ever to reach 1 billion monthly users, per Sensor Tower, and OpenAI reported 900 million weekly active users back in February. The top three assistants combined command 89% of total time spent on AI assistant apps. This isn’t a collapse. It’s a crowding.
But the direction of travel matters. Gemini’s growth is largely structural. Google baked it into Search, Gmail, Docs, and basically every product hundreds of millions of people already use every day. That’s not really a fair fight on the acquisition side, and Sensor Tower acknowledges the integration advantage is doing a lot of the heavy lifting for Gemini’s numbers.
Claude’s story is more interesting. Anthropic hasn’t had Google’s distribution machine or OpenAI’s brand recognition, but it’s built a reputation for being genuinely useful for productivity work. Writers, coders, and analysts keep recommending it in the corners of the internet where people actually talk about this stuff. And Claude is now closing in on ChatGPT’s user-retention rate, which is the metric that really tells you whether people find a product valuable or just downloaded it once and forgot about it.
Trust Is a Feature Now
Here’s the part of the Sensor Tower report that doesn’t get enough attention. When OpenAI announced its deal with the U.S. Department of Defense in February, the platform saw a measurable spike in uninstalls. Not a catastrophic one, but a real, data-visible one.
That’s a signal worth sitting with. Users aren’t just picking AI assistants based on which one writes better emails or codes faster. Brand values and trust are influencing switching behavior at scale. That’s a relatively new dynamic in consumer software, and it suggests AI companies are going to have to think carefully about the partnerships and policy positions they take publicly, not just the features they ship.
It also means the competitive moat isn’t purely technical anymore. If a meaningful slice of users will actually uninstall an app over a government contract, then reputation management is product strategy now.
The Money Math
The broader market numbers in the Sensor Tower report are genuinely striking. In the first half of 2026, people are on pace to download nearly 2.3 billion AI apps and spend over $4.2 billion on them. That’s up from $1.83 billion in spending in H1 2025, which is a big jump in a short time.
The growth rate is decelerating though, even as the absolute numbers climb. Downloads in Asia actually fell 3.3% in Q1 2026, driven by dips in China and India, which are the two largest markets by volume. Asia leads globally in total downloads but trails North America and Europe on in-app spending, which is the number that actually matters for building a sustainable business.
Translation? The easy growth phase is probably over. The industry is shifting from “acquire everyone” to “figure out who will actually pay.”
On that front, Claude is winning a metric that investors should be watching closely. Thirteen percent of Anthropic’s users are paying subscribers, the highest conversion rate in the field. That’s not just a vanity number. It means Anthropic has figured out something about packaging value that its competitors haven’t fully cracked yet, and it makes the company’s revenue picture look more durable than the raw user numbers might suggest.
Ads Enter the Chat
OpenAI started experimenting with ads in ChatGPT back in February. By May, an average of 17% of daily users were being served ads, with software and shopping as the largest advertiser categories, followed by media and entertainment and food and dining. That number has been scaling gradually, which suggests OpenAI is being deliberate about it rather than flooding the product all at once.
The shopping angle is where things get genuinely competitive in a different direction. ChatGPT is increasingly sending referral traffic to retailers like Target, Walmart, and Costco. Amazon, which has blocked ChatGPT’s web crawlers, has seen flat referral traffic from the platform as a result. That’s a real strategic cost for Amazon, and it’s creating room for competitors.
Walmart’s own AI shopping assistant, Spark, has been gaining ground while Amazon’s Rufus has seen flat user growth. Sensor Tower did note that Amazon shoppers who actually used Rufus spent more time in the app and converted at higher rates than non-users, which hints that on-platform AI can meaningfully influence buying behavior when users engage with it. The problem for Amazon is getting users to engage with it in the first place, especially while it’s simultaneously blocking the platform that’s actively routing shoppers to its competitors.
What This Actually Means
The AI assistant market at 1.1 billion users for the leader, 662 million for second place, and 36 billion projected hours of use in H1 2026 alone is no longer a niche. It’s infrastructure. And infrastructure markets tend to consolidate around two or three players who figure out monetization before everyone else runs out of runway.
ChatGPT is still the category leader. But “below 50% for the first time” is the kind of milestone that tends to accelerate the behavior that caused it.
Sensor Tower is scheduled to release its full mid-year AI app spending breakdown in July 2026.
