Earnings per Share

3 Months Ended

Mar. 31, 2015

Basic and diluted earnings per share are calculated as follows:



	For the Three Months Ended March 31,
(In millions)	2015		2014
Numerator:
Net income attributable to Biogen Inc.	$	822.5	$	480.0
Denominator:
Weighted average number of common shares outstanding	235.0		236.8
Effect of dilutive securities:
Stock options and employee stock purchase plan	0.1		0.1
Time-vested restricted stock units	0.3		0.6
Market stock units	0.2		0.3
Dilutive potential common shares	0.6		1.0
Shares used in calculating diluted earnings per share	235.6		237.8

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

The entire disclosure for earnings per share.