Earnings Per Share

The calculations of earnings per share are as follows:



	Three Months Ended September 30,					Nine Months Ended September 30,
($ and shares in millions except per share amounts)	2017			2016		2017		2016
Net (loss) income attributable to Merck & Co., Inc.	$	(56	)	$	2,184	$	3,440	$	4,515
Average common shares outstanding	2,727			2,765		2,735		2,769
Common shares issuable ⁽¹⁾	—			21		19		22
Average common shares outstanding assuming dilution	2,727			2,786		2,754		2,791
Basic (loss) earnings per common share attributable to Merck & Co., Inc. common shareholders	$	(0.02	)	$	0.79	$	1.26	$	1.63
(Loss) earnings per common share assuming dilution attributable to Merck & Co., Inc. common shareholders	$	(0.02	)	$	0.78	$	1.25	$	1.62


⁽¹⁾	Issuable primarily under share-based compensation plans.

The Company recorded a net loss for the three months ended September 30, 2017; therefore, no potential dilutive common shares were used in the computation of loss per common share assuming dilution because the effect would have been antidilutive. For the three months ended September 30, 2016, 4 million, and for the first nine months of 2017 and 2016, 4 million and 13 million, respectively, of common shares issuable under share-based compensation plans were excluded from the computation of earnings per common share assuming dilution because the effect would have been antidilutive.