Novo Nordisk shares dropped 12% after the company announced that semaglutide, the GLP-1 drug behind Ozempic and Wegovy, failed to show any benefit in slowing cognitive decline in early Alzheimer’s disease. The phase 3 EVOKE and EVOKE-Plus trials found no meaningful difference between semaglutide and placebo on key cognitive and functional measures, prompting Novo Nordisk to halt its planned one-year extension while preparing a full data release at the CTAD conference on December 3, 2025. The disappointing results erased tens of billions in market value and disrupted expectations that GLP-1 drugs might play a role in neurodegenerative treatment. Eli Lilly fell 5.2% in sympathy as investors re-evaluated the broader class, while Biogen gained on diminished competitive pressure to its Alzheimer’s pipeline.