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Earnings per Share | 6 Months Ended
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Jun. 30, 2025
Earnings Per Share [Abstract] |
Earnings per Share |
Note 15: | Earnings per Share
Basic and diluted shares outstanding used in our earnings per share calculation are calculated as follows:
|  | For the Three Months Ended June 30, |  | For the Six Months Ended June 30,
(In millions) |  | 2025 |  | 2024 |  | 2025 |  | 2024
Numerator: |  |  |  |  |  |  |  |
Net income attributable to Biogen Inc. |  | $ | 634.8 |  |  | $ | 583.6 |  |  | $ | 875.3 |  |  | $ | 977.0 |
Denominator: |  |  |  |  |  |  |  |
Weighted average number of common shares outstanding |  | 146.5 |  |  | 145.6 |  |  | 146.3 |  |  | 145.4 |
Effect of dilutive securities: |  |  |  |  |  |  |  |
Time-vested restricted stock units |  | 0.2 |  |  | 0.2 |  |  | 0.3 |  |  | 0.4 |
Performance stock units settled in stock |  | — |  |  | 0.1 |  |  | 0.1 |  |  | 0.1 |
Dilutive potential common shares |  | 0.2 |  |  | 0.3 |  |  | 0.4 |  |  | 0.5 |
Shares used in calculating diluted earnings per share |  | 146.7 |  |  | 145.9 |  |  | 146.7 |  |  | 145.9 |
Amounts excluded from the calculation of net income per diluted share because their effects were anti-dilutive were insignificant.

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