**Market Brief: Thomson Reuters Crashes on AI Disruption Fears** **Historic Selloff** Toronto-based **Thomson Reuters (TRI)** witnessed a catastrophic trading session on Tuesday, plunging approximately **18%**. This marks the company’s **biggest daily loss on record** and sends the stock to its lowest closing level since **June 2021**. The sharp decline erased billions in market value, snapping a period of relative stability for the legal and data giant. **The AI Trigger** The massive selloff was triggered by **Anthropic’s** launch of new "Claude Cowork" plugins specifically designed for the legal industry. These AI tools automate core tasks such as contract review, compliance workflows, and legal briefings—services that directly compete with Thomson Reuters' "Westlaw" database and workflow solutions. Investors fear this move signals the beginning of direct, high-level AI competition that could erode the "moat" of traditional legal data incumbents. **Sector-Wide Impact** The panic was not isolated to Thomson Reuters. The entire legal-analytics sector faced a wave of selling pressure: * **RELX (parent of LexisNexis)** dropped approximately **14%**. * **Wolters Kluwer** fell roughly **13%**. * **Pearson** and other professional service firms also saw significant declines. **Market Sentiment & Outlook** Analysts described the market reaction as "shooting first and asking questions later," reflecting deep anxiety over how rapidly Generative AI could commoditize professional services. The crash comes at a critical moment, as Thomson Reuters is scheduled to report its **Q4 earnings results** on **Thursday, February 5, 2026**. All eyes will now turn to management’s commentary on how they plan to defend their market share against this new wave of AI-native competitors.