• Biogen 2023 shares outstanding were 0.146B, a 0.27% decline from 2022.
• Biogen 2022 shares outstanding were 0.146B, a 2.41% decline from 2021.
• Biogen 2021 shares outstanding were 0.15B, a 7.25% decline from 2020.

Shares outstanding can be defined as the number of shares held by shareholders (including insiders) assuming conversion of all convertible debt, securities, warrants and options. This metric excludes the company's treasury shares.