The Corroboration Illusion: When More News Makes LLM Forecasts Less True

Excerpt

arXiv:2609.22246v1 Announce Type: new Abstract: Large language models (LLMs) are increasingly used to forecast real-world events by retrieving and reasoning over news. We show that this dependence on an open, crawlable news corpus creates a new attack surface: an adversary who can merely publish articles--without access to the retriever, the model, or the user's queries--can systematically move the forecaster's output probabilities. We formalize news-corpus poisoning of probabilistic forecasters