16. Earnings Per Share of Common Stock: The following tables provide the computation of basic and diluted earnings per share of common stock for the three and nine months ended September 30, 2018 and 2017.

	For the Three Months Ended
	September 30, 2018		September 30, 2017
Number of shares on which basic earnings per share is calculated:
Weighted-average shares outstanding during period	911,152,848		929,437,441
Add – Incremental shares under stock-based compensation plans	2,566,139		2,236,234
Add – Incremental shares associated with contingently issuable shares	1,493,644		1,553,754

Number of shares on which diluted earnings per share is calculated	915,212,631		933,227,429


Income from continuing operations (millions)	$	2,692	$	2,726
Income/(loss) from discontinued operations, net of tax (millions)	2		0

Net income on which basic earnings per share is calculated (millions)	$	2,694	$	2,726


Income from continuing operations (millions)	$	2,692	$	2,726
Net income applicable to contingently issuable shares (millions)	—		0

Income from continuing operations on which diluted earnings per share is calculated (millions)	$	2,692	$	2,726
Income/(loss) from discontinued operations, net of tax, on which basic and diluted earnings per share is calculated (millions)	2		0

Net income on which diluted earnings per share is calculated (millions)	$	2,694	$	2,726


Earnings/(loss) per share of common stock:
Assuming dilution
Continuing operations	$	2.94	$	2.92
Discontinued operations	0.00		0.00

Total	$	2.94	$	2.92

Basic
Continuing operations	$	2.95	$	2.93
Discontinued operations	0.00		0.00

Total	$	2.95	$	2.93

Stock options to purchase 388,335 shares and 399,844 shares were outstanding as of September 30, 2018 and 2017, respectively, but were not included in the computation of diluted earnings per share because the options’ exercise price during the respective period was greater than the average market price of the common shares, and, therefore, the effect would have been antidilutive.

	For the Nine Months Ended
	September 30, 2018			September 30, 2017
Number of shares on which basic earnings per share is calculated:
Weighted-average shares outstanding during period	915,632,501			935,600,777
Add – Incremental shares under stock compensation plans	3,000,429			3,213,758
Add – Incremental shares associated with contingently issuable shares	1,373,960			1,394,930

Number of shares on which diluted earnings per share is calculated	920,006,890			940,209,466


Income from continuing operations (millions)	$	6,770		$	6,811
Income/(loss) from discontinued operations, net of tax (millions)	7			(3		)

Net income on which basic earnings per share is calculated (millions)	$	6,777		$	6,807


Income from continuing operations (millions)	$	6,770		$	6,811
Net income applicable to contingently issuable shares (millions)	(1		)	(2		)

Income from continuing operations on which diluted earnings per share is calculated (millions)	$	6,769		$	6,809
Income/(loss) from discontinued operations, net of tax, on which basic and diluted earnings per share is calculated (millions)	7			(3		)

Net income on which diluted earnings per share is calculated (millions)	$	6,776		$	6,806


Earnings/(loss) per share of common stock:
Assuming dilution
Continuing operations	$	7.36		$	7.24
Discontinued operations	0.01			0.00

Total	$	7.37		$	7.24

Basic
Continuing operations	$	7.39		$	7.28
Discontinued operations	0.01			0.00

Total	$	7.40		$	7.28

Stock options to purchase 264,628 shares and 146,795 shares (average of first, second and third quarter share amounts) were outstanding as of September 30, 2018 and 2017, respectively, but were not included in the computation of diluted earnings per share because the options’ exercise price during the respective periods was greater than the average market price of the common shares, and, therefore, the effect would have been antidilutive.