TL;DR
On June 11, 2026, Similarweb published its monthly update of AI assistant usage shares. ChatGPT fell to 52.7%, down from 76.4% a year earlier, a drop of nearly 24 points. Meanwhile Gemini jumped to 27.3% and Claude tripled to 8.9%. For your visibility, the message is clear: optimizing for a single AI engine no longer works. The audience is spreading out, and your GEO strategy has to follow.
On June 11, 2026, Similarweb published on LinkedIn its twelve-month comparison of consumer AI assistant usage shares, and the headline number is ChatGPT's drop: from 76.4% a year ago to 52.7% today. Over the same period, Gemini climbed from 8.9% to 27.3% and Claude tripled, going from 1.6% to 8.9%, as PPC Land detailed from the Similarweb data.
ChatGPT is still the leader, but it is no longer dominant. In a single year, the AI assistant market went from a near-monopoly to a multi-player landscape. For a business that wants to be cited by AI, this shift changes everything: the target is no longer one engine, it is a portfolio of engines.
What the barometer actually says
Read it carefully. The Similarweb barometer measures usage of AI assistants and chatbots (traffic to ChatGPT, Gemini, Claude, Perplexity and the rest), not classic web search market share, where Google remains overwhelmingly dominant. The data, current through May 26, 2026, gives this ranking:
| AI assistant | 1 year ago | Today | Change |
|---|---|---|---|
| ChatGPT | 76.4% | 52.7% | −23.7 pts |
| Gemini | 8.9% | 27.3% | +18.4 pts |
| Claude | 1.6% | 8.9% | +7.3 pts |
| DeepSeek | 5.3% | 4.0% | −1.3 pt |
| Grok | 2.8% | 2.8% | = |
| Copilot | 1.9% | 2.0% | +0.1 pt |
| Perplexity | 1.8% | 1.3% | −0.5 pt |
Over the most recent month measured, Claude posted the largest gain (+2.9 points), ahead of Gemini (+1.8 points). The underlying trend, summed up by a commenter under the Similarweb post, is plain: "the traffic share is becoming more decentralised over time."
Why Gemini and Claude are taking off
Gemini's rise is no accident. Since Google I/O 2026, Gemini 3.5 Flash has become the default model in the Gemini app and in Search's AI Mode, and it is pushed across the Android ecosystem. When an assistant is the default in both search and the phone, usage follows mechanically. It is the same dynamic seen when Gemini overtook Perplexity in AI referral traffic.
Claude plays a different tune: it captures professional and technical use, where reasoning quality and writing matter most. Tripling its share in a year without massive consumer distribution is the mark of adoption driven by usefulness, not by default placement.
Why this matters for you: each engine has its own way of searching, citing and displaying sources. Content that surfaces in ChatGPT does not automatically surface in Gemini or Claude. The more the audience fragments, the more fragile single-engine visibility becomes.
For your strategy, the single bet is over
For two years, "being visible in AI" mostly meant "being cited by ChatGPT." With nearly half of usage now elsewhere, that shortcut is expensive. If Gemini accounts for more than a quarter of usage and you have never checked how it cites you, you are ignoring a channel as large as ChatGPT was in its early days.
The good news: the fundamental levers of GEO (Generative Engine Optimization) are largely shared across engines. Direct answers at the top of the page, sourced and quantified data, clear structure, schema.org markup: these are the signals that make content citable, whatever the engine. The perceived credibility of a source weighs heavily in what AI chooses to cite.
You know what ChatGPT says about you, but what about Gemini and Claude?
Cicéro runs a free, multi-engine GEO diagnostic: what AI says about your brand, and how to show up there.
What to do now
- Test your visibility on 3 engines, not one. Ask your core business queries to ChatGPT, Gemini and Claude. Note who cites you, who ignores you, and with what link.
- Measure real traffic by engine. Analytics tools can now separate traffic coming from ChatGPT, Claude and Gemini. Without that measurement, you are flying blind.
- Optimize for citability, not for one engine. Direct answers, named sources, verifiable data, structure and schema.org: this foundation serves every engine at once.
- Watch the trend, not the frozen ranking. Claude tripling in a year shows positions move fast. What matters is the direction of the engines your audience is migrating to.
Our take
The real story is not "ChatGPT is declining," it is "the market is decentralizing." For an SME, that is an opportunity: a multi-engine landscape means several entry points to your prospects, and several chances to be cited. The risk is not picking the wrong engine, it is continuing to target only one while your audience spreads across five. AI visibility in 2026 is a plural game.
What this article does not cover
These figures measure AI assistant usage, not classic web search: Google remains by far the leading traditional search engine. Audience-measurement methodologies vary from one provider to another, and a monthly barometer is a snapshot, not a forecast. Finally, we do not get into the technical setup of per-engine tracking, which depends on your analytics stack.
Frequently asked questions
What is ChatGPT's market share in 2026?
Why are Gemini and Claude growing so fast?
Should I optimize my content for ChatGPT or for Gemini?
Does this data measure classic Google Search?
Sources
- → PPC Land: "ChatGPT drops to 52.7% as Claude triples its AI traffic share" (June 11, 2026), based on Similarweb data
- → Similarweb: monthly barometer of AI assistant usage shares (published on LinkedIn June 11, 2026, data through May 26, 2026)
- → Google (official blog): Gemini 3.5 Flash as the default in Search and AI Mode (Google I/O 2026)
Growth and SEO content strategist, I founded Cicéro to help businesses build lasting organic visibility, on Google and in AI-generated answers alike. Every piece of content we produce is designed to convert, not just to exist.
LinkedIn