Analyzing over 50 advertisers: how AI search is reshaping web traffic

Since Google rolled out AI Overviews in 2024, the feature has appeared in an increasingly large share of search results. According to Ahrefs, that shift has cut web traffic to some sites by as much as 58%, as users increasingly stay on Google's own results page instead of clicking through.

Understanding exactly how this shift is affecting advertisers isn't straightforward, since the impact varies widely by business. An analysis of Google Analytics data from marketing services group Brainlabs, covering 54 clients — 24 U.S. companies, 24 U.K. companies, and 29 large advertisers with at least 1,000 employees — found organic web traffic fell by more than 10% on average after AI Overviews rolled out.

The data spans 14 months, from January 2025 through this past April. According to Sam Pace, the company's senior SEO manager, AI Overviews began appearing in at least 30% of U.S. search results last September — a "tipping point" for clients. After crossing that threshold, visits from AI sources like ChatGPT or Gemini climbed to an average of 200,000 a month, while organic visits fell from roughly 20 million to under 15 million a month. Of the 54 clients, 46 saw declines — with the combined total dropping from 140.1 million to 125.4 million sessions, a 10.5% decrease, even as sessions from AI platforms rose 163% over the same period.

Yet the drop in traffic hasn't translated into negative commercial outcomes. Brainlabs also tracked "key events" — actions like purchases, newsletter sign-ups or full page views. Key events attributed to AI-driven traffic rose 335%, and the conversion rate for such events was 1.5 times higher among visitors arriving via ChatGPT, Copilot, Gemini and Perplexity than among those coming from organic search. In other words, even as traffic declines, the users who do arrive are far more likely to make a purchase or engage with the brand — because they're further along in their product search.

The impact varies significantly by industry: fitness, fintech, insurance and CPG brands saw the steepest declines, likely reflecting categories where consumers carefully compare options before buying. Retail, beauty and entertainment saw the smallest drops in organic traffic and the strongest growth in AI-driven visits.

Among AI search apps, ChatGPT leads by a wide margin in user numbers — it reached 1 billion monthly active users in May, compared with just 56 million for Claude, according to Sensor Tower. Pace also noted that the real volume of AI-driven visits is likely higher than reported, since some users navigate to a site through a separate browser window rather than clicking directly from an AI app, causing those visits to be logged as "direct traffic" instead. "This is a channel that absolutely needs to be part of your daily metrics," he said.