3 Months of AI Visibility Index Data: Here's What We've Learned About AI Search

Launched in September, the AI Visibility Index is the industry’s definitive AI visibility benchmark, tracking how large language models like ChatGPT and Google AI Mode cite brands and sources. It helps marketers understand how AI search is reshaping brand visibility across 5 different industries:

Semrush now has three full months of data that reveals how ChatGPT and Google AI Mode are shaping what users see, trust, and click on.

Our latest analysis exposes fast-moving changes in source diversity, brand visibility, and ranking volatility, showing that AI search is anything but stable.

1. Reddit’s big correction: Once dominating ChatGPT results, Reddit’s frequency as a source has dropped. However, it still remains a top-10 source across all categories. Meanwhile, its presence in Google AI Mode surged 75%, making it the platform’s second-most cited source.

2. ChatGPT favors diversity: The model now uses 80% more sources than in August, suggesting ongoing updates and a move toward more varied answers.

3. Google AI Mode stays conservative: Brand and source diversity declined slightly, signaling tighter control over which results appear.

4. Brand stability at the top: Only 25 new brands entered the top 100 across both models, confirming that while AI search is volatile, leading brands hold their ground.

5. Overall, each model has different rules but the same goal: ChatGPT and Google AI Mode agree on 67% of mentioned brands but only 30% of sources, meaning marketers must optimize for each ecosystem separately.

AI search is evolving faster than traditional SEO ever did. Understanding where your brand appears—and which sources fuel those answers—is critical for brand visibility and trust.ChatGPT and Google AI Mode mention many of the same brands (67% overlap), but rely on very different sources (only 30% overlap). 

For marketers, brand managers, and PR professionals, that means visibility now depends on optimizing across AI models, not just one.

Dive deeper into brand and source performance across all five categories with the interactive AI Visibility Index, then download the blueprint for your brand to succeed.