Key Takeaways

  • A 13-week study tracked 230k prompts and 100M+ AI citations.
  • In mid-September, ChatGPT cut Reddit and Wikipedia citations fast.
  • Yet both still lead ChatGPT’s cited sources after the drop.
  • Google’s AI Mode favors Google-owned domains like YouTube and Google Blog.
  • Perplexity often cites Reddit, LinkedIn, NIH, Microsoft, and Google.
  • After September, PR Newswire, Forbes, and Medium gained on ChatGPT.
  • The timing aligned with Google ending the num=100 results trick.

What Does “Most-Cited Domains by AI” Mean?

AI tools often show source links in answers. These links point to domains. When we count how often each domain shows up, we see who AI “trusts” most. This matters because citations drive clicks, reach, and authority.

Why Did This Study Matter in 2025?

AI answers shape user journeys. Therefore, the sources they cite gain power. In 2025, citation patterns shifted. Notably, ChatGPT changed fast in September. So, brands must watch which sites AI prefers and adapt content plans.

What Did the Study Measure and When?

The study checked weekly citations for 13 weeks. It covered ChatGPT, Google’s AI Mode, and Perplexity. It analyzed 230k prompts and over 100M citations from July 14 to October 12, 2025. This gives a clear quarter-view of change.

Which Domains Do AIs Cite Most Right Now?

ChatGPT still cites Reddit and Wikipedia the most, even after cuts. Google’s AI Mode shows a balanced mix and leans into Google properties. Perplexity highlights Reddit, LinkedIn, NIH, Microsoft, and Google. The mix varies by platform and week.

What Changed for Reddit and Wikipedia in September?

In early August, ChatGPT cited Reddit in close to 60% of answers. By mid-September, that fell near 10%. Wikipedia dropped from about 55% to under 20% on ChatGPT. However, both stayed steadier on AI Mode and Perplexity. The shift was not universal.

Did Google’s num=100 Change Play a Role?

SEOs linked the timing to Google ending the num=100 parameter in mid-September. That move broke deep SERP scraping habits. The study notes the timing match. Yet it also suggests other reasons, like reducing over-citation and bias. So, treat it as one factor, not the only one.

Which Sites Won and Lost After September?

On ChatGPT, PR Newswire, Forbes, and Medium gained share. TechRadar fell along with Reddit and Wikipedia. On AI Mode, UGC sites like YouTube and Reddit rose, while Medium, Quora, and LinkedIn dipped. Perplexity changed less, though Reddit slid a bit.

How Do Platforms Differ in Citation Style?

  • ChatGPT: Big swings. Heavy Reddit/Wikipedia before September, then a rebalance.
  • AI Mode: Stable mix. Lower Wikipedia share. Strong pull toward Google-owned domains.
  • Perplexity: Steady patterns. Strong showings for Reddit and expert/government sources.

What Should Marketers Do Next (Step-By-Step)?

  1. Audit your sources. List which domains your content cites and earns links from. Match them to each AI’s favorites.
  2. Aim for expert hubs. Publish original data, FAQs, and how-tos. Therefore, you become citable and scannable.
  3. Diversify coverage. Win citations beyond Reddit/Wikipedia. Pitch to Forbes-style outlets and trusted.gov/.edu pages.
  4. Use entity clarity. Add schema, clear bylines, and org details. This helps AIs resolve who said what.
  5. Track weekly. Watch citation share by platform. Then adjust outreach and content types fast.
  6. Build UGC presence. Engage on Reddit, LinkedIn, and YouTube. But keep quality and moderation tight.
  7. Mind timing shifts. Align analysis with search platform changes, not just traffic swings.

What Benefits Can You Expect?

  • More AI mentions. Right formats and sources earn more citations.
  • Stable traffic. Diverse placements reduce risk from sudden shifts.
  • Brand trust. Expert content and clean entities raise authority across AIs.

Did You Know?

Wikipedia’s share on Google’s AI Mode hovered near ~2% during the study window. Yet it remained a top source for ChatGPT before the September drop.

Conclusion

AI citation patterns are moving targets. In Q3 2025, ChatGPT rapidly rebalanced away from Reddit and Wikipedia, while AI Mode stayed steady and favored Google properties. Meanwhile, Perplexity leaned on both UGC and expert sources. Track these shifts weekly, publish expert content, and build relationships with trusted domains. That way, you earn citations no matter how AI answers evolve.

FAQs

What time period did the study cover?

Thirteen weeks from July 14 to October 12, 2025.

Which AI tools were analyzed?

ChatGPT, Google’s AI Mode, and Perplexity.

Which domains gained after September?

On ChatGPT, PR Newswire, Forbes, and Medium gained share.

Did Google’s num=100 removal cause the drop?

It aligned in time. However, other factors likely played roles too.

How should I increase my chances of being cited?

Publish expert, citable content. Also, build links and presence on trusted domains.

References