The AI visibility index: which brands are vanishing from AI answers

Marketing agency Fractl ran a study across eight industries, putting the same queries on 96 topics to GPT-4o, Gemini 2.5 Flash and Claude Sonnet 4.6 — 15 times each, for a total of 4,320 responses and more than 8,500 unique brand mentions. The results were then compared against Ahrefs SEO data (domain rating, organic traffic, keyword volume).

For more than 90% of brands the relationship was as expected: a strong traditional search reputation usually lined up with stronger AI visibility. But the rest revealed surprising gaps. About 5% of brands (471 companies) had high domain ratings and heavy organic traffic yet were barely mentioned in AI answers at all. Meanwhile, roughly 4% (377 brands) with comparatively weak SEO metrics were mentioned far more often than expected — examples cited include Stripe in fintech (financial technology), Notion in SaaS (cloud software) and Coursera in education.

The authors pinpointed the main cause: in about 9% of cases, how often a brand was mentioned in third-party content — reviews, ranking round-ups and comparison articles not written by the brand itself — was directly tied to AI visibility. In other words, what matters for an AI's "memory" is less what a brand says about itself and more what the rest of the internet says about it.

Another key finding: only 11% of the brands studied (900 companies) were mentioned equally by all three models, while 77% were named by just one. Notion, for instance, came up 17 times more often in Claude than in Gemini, and Whoop nearly four times more often. That means a single "AI visibility" metric can be misleading — a brand can win in one model and vanish entirely in another.

Fractl's authors offer marketers five practical takeaways. First, domain rating and organic traffic still matter, but they are not enough. Second, third-party mentions (digital PR, comparison pieces, reviews) are becoming one of the most effective ways to boost AI visibility. Third, each model (ChatGPT, Gemini, Claude) has to be tracked separately. Fourth, if a well-known brand goes unmentioned in a specific category, the problem may lie in which category the model has "filed" it under. Fifth, some sectors (health, travel) are still open, while others (finance, large SaaS) are already "hardening," making them ever harder for new brands to break into.