Bristol Myers Squibb and Johnson & Johnson announced a Phase III futility readout in their acute coronary syndrome trial of milvexian, a selective Factor XIa inhibitor, and will halt that study. The failure raises questions about the therapeutic window and clinical utility of next‑generation anticoagulants targeting Factor XIa and will influence ongoing trials in atrial fibrillation and secondary stroke prevention. Developers and investors will reassess timelines and go/no‑go criteria for remaining milvexian programs while competitors in the anticoagulation space monitor implications for clinical strategy.