NET INCOME PER SHARE ATTRIBUTABLE TO GILEAD COMMON STOCKHOLDERS

Basic net income per share attributable to Gilead common stockholders is calculated based on the weighted-average number of shares of our common stock outstanding during the period. Diluted net income per share attributable to Gilead common stockholders is calculated based on the weighted-average number of shares of our common stock outstanding and other dilutive securities outstanding during the period. The potentially dilutive shares of our common stock resulting from the assumed exercise of outstanding stock options and equivalents, the assumed conversion of our outstanding Convertible Notes and the assumed exercise of the warrants related to our outstanding Convertible Notes were determined under the treasury stock method. Both the Convertible Notes and the associated warrants were settled in 2016.

We excluded stock options and equivalents of approximately 13 million, 11 million and 3 million weighted-average shares of our common stock that were outstanding during 2018, 2017 and 2016, respectively, in the computation of diluted net income per share attributable to Gilead common stockholders because their effect was antidilutive.

The following table shows the calculation of basic and diluted net income per share attributable to Gilead common stockholders (in millions except per share amounts):



	Year Ended December 31,
	2018		2017		2016
Net income attributable to Gilead	$	5,455	$	4,628	$	13,501
Shares used in per share calculation - basic	1,298		1,307		1,339
Effect of dilutive securities:
Stock options and equivalents	10		12		13
Conversion spread related to the Convertible Notes	—		—		2
Warrants related to the Convertible Notes	—		—		4
Shares used in per share calculation - diluted	1,308		1,319		1,358
Net income per share attributable to Gilead common stockholders - basic	$	4.20	$	3.54	$	10.08
Net income per share attributable to Gilead common stockholders - diluted	$	4.17	$	3.51	$	9.94