In Q2 2025, we detected a significant shift in ChatGPT's citation sourcing: a dramatic move away from Bing-indexed content toward Google-indexed content. This is one of the most significant structural changes in AI search since the emergence of retrieval-augmented generation.
Our analysis compared citation source overlap between ChatGPT responses and major search engine results across 100,000 prompts from Q1 and Q2 2025. The Bing-ChatGPT overlap dropped from 73% to 31%. The Google-ChatGPT overlap increased from 18% to 64%.
Why this matters for brands
This shift means that Google SEO rankings are now a more direct predictor of ChatGPT citation likelihood than they were 6 months ago. Brands that invested heavily in Google SEO while ignoring AI visibility now have a structural advantage — their Google-optimized content is more likely to appear in ChatGPT citations.
Conversely, brands that had optimized specifically for Bing to capture ChatGPT citations may need to revisit their strategy. The correlation between Bing ranking and ChatGPT citations has weakened significantly.
The integrated optimization era
This data suggests we're entering an era of integrated optimization, where Google SEO and AEO are more tightly coupled than before. Strong Google performance supports AI citation visibility, and strong AI visibility drives Google-measured brand engagement. The two disciplines are converging.