Earnings per Share

12 Months Ended

Dec. 31, 2015

Basic and diluted earnings per share are calculated as follows:



	For the Years Ended December 31,
(In millions)	2015		2014		2013
Numerator:
Net income attributable to Biogen Inc.	$	3,547.0	$	2,934.8	$	1,862.3
Denominator:
Weighted average number of common shares outstanding	230.7		236.4		236.9
Effect of dilutive securities:
Stock options and employee stock purchase plan	0.1		0.1		0.3
Time-vested restricted stock units	0.3		0.5		0.8
Market stock units	0.1		0.2		0.3
Dilutive potential common shares	0.5		0.8		1.4
Shares used in calculating diluted earnings per share	231.2		237.2		238.3

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

Earnings per share for the years ended December 31, 2015, 2014 and 2013, reflects, on a weighted average basis, the repurchase of 4.6 million shares, 1.0 million shares and 0.9 million shares, respectively, of our common stock under our share repurchase authorizations.