Biogen (BIIB) stock has declined 20.9% so far this year against an increase of 28.6% for the industry. The stock has also underperformed the sector and the S&P 500 index, as seen in the chart below.BIIB Stock Underperforms Industry, Sector & S&P 500Image Source: Zacks Investment ResearchThe company’s stock performance has been below most large drugmakers’ performance. Biogen's revenues declined 3.3% in the first six months of 2024. Sales of Biogen’s key multiple sclerosis (“MS”) drugs like Tecfidera and Tys ...