v3.25.3
Earnings per Share (Tables)
 9 Months Ended
Sep. 30, 2025
Earnings Per Share [Abstract]  
Basic and diluted earnings per share
Basic and diluted shares outstanding used in our earnings per share calculation are calculated as follows:
For the Three Months Ended September 30,For the Nine Months Ended September 30,
(In millions)2025202420252024
Numerator:
Net income attributable to Biogen Inc.$466.5 $388.5 $1,341.8 $1,365.5 
Denominator:
Weighted average number of common shares outstanding146.6 145.7 146.4 145.5 
Effect of dilutive securities:
Time-vested restricted stock units0.5 0.3 0.4 0.4 
Performance stock units settled in stock— 0.1 — 0.1 
Dilutive potential common shares0.5 0.4 0.4 0.5 
Shares used in calculating diluted earnings per share147.1 146.1 146.8 146.0