Novo Nordisk's Alzheimer's drug failure represents a devastating blow that wiped $20 billion from the company's market value in a single day. The Danish drugmaker desperately needed this win after a year of sliding shares and slowing sales, but their own executives called it a "lottery ticket" that turned out worthless. This massive 10% stock plunge shows investors have lost confidence in Novo's ability to escape the quicksand it's stuck in.