Earnings Per Share

Basic net income (loss) per share attributable to Vertex common shareholders is based upon the weighted-average number of common shares outstanding during the period, excluding restricted stock, restricted stock units and performance-based restricted stock units, or “PSUs,” that have been issued but are not yet vested. Diluted net income per share attributable to Vertex common shareholders is based upon the weighted-average number of common shares outstanding during the period plus additional weighted-average common equivalent shares outstanding during the period when the effect is dilutive.

The following table sets forth the computation of basic and diluted net income (loss) per share for the periods ended:



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
	(in thousands, except per share amounts)
Basic net income (loss) attributable to Vertex per common share calculation:
Net income (loss) attributable to Vertex common shareholders	$	128,746		$	(102,952	)	$	546,369		$	162,800
Less: Undistributed earnings allocated to participating securities	(14		)	—			(161		)	(203		)
Net income (loss) attributable to Vertex common shareholders—basic	$	128,732		$	(102,952	)	$	546,208		$	162,597

Basic weighted-average common shares outstanding	254,905			250,268			254,096			247,963
Basic net income (loss) attributable to Vertex per common share	$	0.51		$	(0.41	)	$	2.15		$	0.66

Diluted net income (loss) attributable to Vertex per common share calculation:
Net income (loss) attributable to Vertex common shareholders	$	128,746		$	(102,952	)	$	546,369		$	162,800
Less: Undistributed earnings allocated to participating securities	(13		)	—			(158		)	(200		)
Net income (loss) attributable to Vertex common shareholders—diluted	$	128,733		$	(102,952	)	$	546,211		$	162,600

Weighted-average shares used to compute basic net income (loss) per common share	254,905			250,268			254,096			247,963
Effect of potentially dilutive securities:
Stock options	2,962			—			2,990			2,700
Restricted stock and restricted stock units (including PSUs)	1,896			—			1,866			1,204
Employee stock purchase program	25			—			20			228
Weighted-average shares used to compute diluted net income (loss) per common share	259,788			250,268			258,972			252,095
Diluted net income (loss) attributable to Vertex per common share	$	0.50		$	(0.41	)	$	2.11		$	0.64

The Company did not include the securities in the following table in the computation of the net income (loss) per share attributable to Vertex common shareholders calculations because the effect would have been anti-dilutive during each period:



	Three Months Ended September 30,		Nine Months Ended September 30,
	2018	2017	2018	2017
	(in thousands)
Stock options	2,572	10,278	2,152	3,904
Unvested restricted stock and restricted stock units (including PSUs)	1	4,241	4	281