AI search in October 2026: GPT-6, Gemini 4, Claude 5.5 and what brands can do

October brought new models to ChatGPT, Gemini and Claude, more links and more ads in AI search, and a week in which visits from ChatGPT went missing from analytics. Each change is dated and linked to its source, with what a brand can do about it.

At a glance

• 7 and 8 October: GPT-6 becomes the model behind ChatGPT.
• 7 October: Claude Haiku 5.5 follows Claude Opus 5.5 and Sonnet 5.5, introduced in late September.
• 9 to 15 October: links in ChatGPT's answers lose their tracking tag, so its visits show up as direct traffic.
• 13 October: Gemini 4 Argon reaches the Gemini app for paying subscribers.
• 15 October: Google puts more links, and higher, in AI Overviews and AI Mode, and tests a section for official websites.
• 21 October: ChatGPT ads reach 89 countries.
• 28 October: Google reports one billion Gemini app users and questions three times longer in AI Mode.
• 28 October: Google takes ads in AI Mode to 10 more countries and opens AI Mode and Gemini to apps that companies build.

New models behind three assistants

OpenAI began rolling out GPT-6 in ChatGPT on 7 October: GPT-6 Sol on the paid plans that day, and GPT-6 Luna on the Free and Go plans from 8 October. With it came what OpenAI calls Intelligent UI, answers that mix text with charts, buttons and small interactive tools. OpenAI says GPT-6 Instant starts answering questions that need a web search 44% sooner than GPT-5.6 Instant, measured as the time until the answer begins (OpenAI's announcement, via its community forum; 9to5Mac).

Anthropic introduced Claude Opus 5.5 on 22 September, Claude Sonnet 5.5 on 28 September and Claude Haiku 5.5 on 7 October (Anthropic).

Google began rolling out Gemini 4 Argon in the Gemini app on 13 October for Google AI Pro and Ultra subscribers. The same day, Gemini began rolling out a Customize menu to every user, which connects more than 40 apps, Instacart among them (Gemini release notes).

What to do

• A new model can name other brands for the same question, describe them differently and rely on other sources. Look at how each assistant now answers the questions your buyers ask most, and how it describes your brand: what you sell, your prices, who you are compared with.
• Judge from many answers, not one. When SparkToro asked ChatGPT and Google's AI the same brand questions 60 to 100 times, the same list of brands came back less than once in a hundred runs (SparkToro, January 2026).
• Answers collected before these dates came from the old models. Keep them, and compare like with like.
• Free and paid users of Gemini now get answers from different models. A brand can appear for one group and not the other.
• Where an assistant gets a fact about you wrong, the fix starts with the pages it reads: your own site first, then the reviews, listings and articles that describe you.

A week of missing ChatGPT visits

Links inside ChatGPT's answers normally carry the tag utm_source=chatgpt.com, which is how analytics tools recognise a visit from ChatGPT. After the GPT-6 rollout, links in the answer text stopped carrying it, while links in the sources panel and in shopping results kept it. Data from Graphite shows the drop starting on 9 October. Cedric Huesler of Adobe said OpenAI confirmed to him on 14 October that it was a bug, and that a fix began rolling out early on 15 October. Across about 500 pages where ChatGPT brought at least 5% of visits, Huesler counted about 31,000 fewer ChatGPT visits a day from 9 to 13 October and about 26,000 more direct visits a day (Search Engine Journal, 15 October).

What to do

• Add a note to your analytics for 8 to 15 October, so no one reads that week as a fall in interest.
• Before reporting a drop in ChatGPT visits for October, look at direct visits to the pages ChatGPT usually sends people to. If they rose that week, the visitors kept coming and were counted under the wrong source.

More links, and a place for official sites, in Google's AI answers

On 15 October Google said it has substantially increased the number of links inside AI Overviews and AI Mode answers, and shows them higher in the answer more often. It is testing a section at the top of some answers with one or two official websites and a line on why each is useful, for tasks that need a particular site. Links to related articles at the end of an answer now come with pictures, and news carousels are spreading to more countries and languages. Google also said the use of Preferred Sources, which lets people pick the publications they want to see more of, has grown more than sevenfold since January (Google, 15 October).

What to do

• Make the pages an answer would link to worth the click: your home page and your product, pricing, booking and location pages, fast to load and with the facts near the top.
• Make it easy to tell which site is yours: the same name, address and logo on your site, your social profiles and your listings, and Organization markup (JSON-LD) on your site that names your official profiles.
• If you publish news or research, ask your readers to add you as a Preferred Source.

ChatGPT ads now run in 89 countries

On 21 October OpenAI brought ChatGPT ads to 26 more countries, 89 in all, including 14 in Latin America as well as Nigeria, South Africa and Ukraine. More than 100,000 advertisers have run campaigns since ads began just over eight months earlier. Ads show only on the Free and Go plans; Plus, Pro and Enterprise stay without them. OpenAI repeats that "advertising does not influence the answers ChatGPT provides" and that ads are labelled and kept separate from the answer (OpenAI; The Next Web, 21 October).

What to do

• Keep ads and answers apart in your plans and your reports. An ad reaches Free and Go users, beside the answer. Being named in the answer reaches every user, on every plan, and on OpenAI's account no ad budget changes it.
• If you run ChatGPT ads, count an ad click as an ad click, never as a mention.

Google's quarter: one billion Gemini users, and longer questions

In its results for July to September, published on 28 October, Alphabet said the Gemini app now has one billion users and that Search queries grew faster than at any time in the last five years. Sundar Pichai added that questions asked in AI Mode are on average three times longer than traditional searches, and that one in five AI Mode searches uses voice, an image or a document. Revenue from Google Search and other grew 12% to $63.35 billion (Alphabet's results, filed with the SEC; Sundar Pichai's remarks).

What to do

• A question three times longer says more about the buyer: a budget, a team size, a place, a constraint. An answer can name a brand for one kind of buyer and leave it out for another.
• Write pages that answer those situations in plain words, such as who your product suits, what it costs and where you serve, and track the long questions your buyers actually ask.

Also on 28 October: ads in more countries, and company apps in AI Mode

Google took ads in AI Mode to 10 more countries, Australia, Canada and India among them, with Brazil, Mexico and the United Kingdom planned before the end of the year. In the US, ads can now also appear on follow-up questions (Google, 28 October). The same day Google opened a preview that lets a business build an app for AI Mode, the Gemini app or both (Google, 28 October).

What to do

• If you sell in one of the new countries, look at the answers your buyers see in AI Mode and whose ads sit beside them. The steps are in our post on AI Mode ads beyond the US.
• If people come to you to get something done, such as ordering or booking, ask your developers whether an app for AI Mode and Gemini fits. How it works is in our post on company apps in AI Mode and Gemini.

From September, still rolling out: Siri AI

Apple released iOS 27 with Siri AI on 14 September (Engadget). Apple's page on its web crawler, Applebot, says the content it collects helps Siri and Search answer broad questions with answers "that may include links to sources". The same page says that blocking Applebot-Extended, which only governs the training of Apple's models, does not remove a site from search results (Apple, 4 September).

What to do

• Check that your robots.txt lets Applebot in. If you do not want your pages used to train Apple's models, block Applebot-Extended instead: you stay in Siri's and Spotlight's results.

How we follow these changes

Visibian asks seven assistants the same buyer questions again and again, daily or weekly, which is how changes like these show up in a brand's numbers. To get the next roundup when it is out, follow the newsroom's feed.