Jeff Horwitz

Authors & Journalists · The Wall Street Journal (formerly), Reuters

Investigative reporter behind the Facebook Files and a 2025 Meta AI-chatbot exposé that helped force internal research on teen harm into public view.

Jeff Horwitz is the investigative journalist who broke The Wall Street Journal's Facebook Files series, reporting that surfaced Meta's own internal research on Instagram's effects on teen mental health and helped set the stage for Frances Haugen's 2021 Senate testimony. He turned that reporting into the 2023 book Broken Code. In 2025, reporting for Reuters, he exposed problems with Meta's AI chatbots, work that contributed to a 2026 Pulitzer Prize for beat reporting. Across both stories, his reporting has repeatedly turned platforms' internal, unpublished research into public evidence of harm to young users.