A dramatic shift in website citation proportions has been observed in ChatGPT Search, OpenAI's AI search feature. According to reports based on data from Promptwatch, the citation share of Reddit, which was the most frequently cited site by ChatGPT as of April 2026, dropped to an average of 0.52% between 2026-08-14 and 2026-08-17. This represents an 86% decrease from the 3.8% level seen just a few days prior.
Technical changes in how ChatGPT performs web searches have been pointed out as the reason for this sharp decline. According to Promptwatch's observations, ChatGPT Search began heavily utilizing the "site:" operator to limit searches to specific websites starting on 2026-08-08, which reportedly led to a significant increase in the proportion of information retrieved by visiting specific sites directly. While OpenAI has not provided an explanation for this specification change, it is reported that no similar drop has been observed in Google's AI search features, suggesting this behavior is unique to ChatGPT.
Source: OpenAIがAI検索仕様を変更、Redditの引用シェアが数日で3.8％から0.5％に崩落 - Yahoo!ニュース (Google News: OpenAI)