Earnings per Share

9 Months Ended

Sep. 30, 2024

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)	2024		2023		2024		2023
Numerator:
Net income (loss) attributable to Biogen Inc.	$	388.5	$	(68.1)	$	1,365.5	$	911.4
Denominator:
Weighted average number of common shares outstanding	145.7		144.8		145.5		144.7
Effect of dilutive securities:

Time-vested restricted stock units	0.3		—		0.4		0.7

Performance stock units settled in stock	0.1		—		0.1		0.1
Dilutive potential common shares	0.4		—		0.5		0.8
Shares used in calculating diluted earnings per share	146.1		144.8		146.0		145.5

Amounts excluded from the calculation of net income (loss) per diluted share because their effects were anti-dilutive were insignificant.