Previsible analyzed 6.77 million LLM-driven sessions across 166 GA4 properties from November 2024 to May 2026. The finding: ChatGPT accounts for 92.4% of all standalone AI referral traffic, up from roughly 84% in December 2025. Monthly LLM sessions grew 9.9x, reaching 644,478 in May 2026.

The data surfaces three shifts worth noting. First, Claude grew 64x over the 19-month period and overtook Perplexity in March 2026, with Perplexity down 61% from its peak. Second, Gemini is the quiet #2 at 3.2x growth with low volatility. Third — and most actionable — 28.8% of ChatGPT referrals land on internal search result pages, not specific content. AI models are sending users to the domain's own search box when they can't surface a direct answer. If your site search is broken or returns weak results, you're losing nearly a third of the AI traffic you actually earn.

WebFX tracking across 200+ accounts finds that brands consistently cited in AI-generated answers see 2.3x higher branded search volume than comparable brands not cited in AI results — even when controlling for ad spend and domain authority. The mechanism: AI platforms name the brand, users later Google the brand name directly. Getting cited by ChatGPT or Perplexity doesn't just drive referral clicks — it seeds the discovery funnel for branded intent searches that convert at 4-6x the rate of generic queries. AI visibility has become a leading indicator of brand equity, not just a traffic source.

"Everyone will cite the 92.4% ChatGPT figure and conclude you should optimize for ChatGPT. That's the right tactical takeaway — but the strategic insight is buried one level deeper: Claude grew 64x in 19 months and has already overtaken Perplexity. We are watching a market reshape in real time, and the brands who bet exclusively on one platform will be wrong on a short enough timeline. The Semrush data reinforces this — only 36 brands maintained top-100 visibility across all four AI engines simultaneously. That cross-platform coverage is what I'd be building toward, not deeper moats on any single platform. The 28.8% internal-search routing stat is the most underrated finding in this whole set: if your site search is broken, you're leaking a third of the AI traffic you actually earn."