In pharma, you can take a larger slice of the healthcare pie than your peers, but you are still constrained by the size of the pie. No matter how good your cancer or diabetes drug is, healthcare systems will still have to keep paying for heart disease and rheumatoid arthritis treatments too.

That, in a nutshell, is why the divergence of obesity-diabetes companies from the rest of the industry in recent years can’t go on forever. In 2023, Eli Lilly and Novo Nordisk have risen more than 50% each, to become the two largest pharma companies by market capitalization, with their combined value now hovering around $1 trillion. By comparison, the rest of the industry badly underperformed the market, with the NYSE Arca Pharmaceutical Index rising a measly 4% compared with 24% for the S&P 500.