v3.26.3
Earnings per Share (Tables)
 9 Months Ended
Sep. 30, 2026
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)2026202520262025
Numerator:
Net (loss) income attributable to Biogen Inc.$(20.6)$466.5 $396.4 $1,341.8 
Denominator:
Weighted average number of common shares outstanding147.8 146.6 147.5 146.4 
Effect of dilutive securities:
Time-vested restricted stock units— 0.5 1.2 0.4 
Performance stock units settled in stock— — 0.2 — 
Dilutive potential common shares— 0.5 1.4 0.4 
Shares used in calculating diluted earnings per share147.8 147.1 148.9 146.8