Net (Loss) Income Per Share

Basic net (loss) income per share is calculated by dividing net (loss) income by the weighted average number of shares outstanding during each period. Diluted net (loss) income per share is calculated by dividing net (loss) income by the diluted number of shares outstanding during each period. Except where the result would be anti-dilutive to net (loss) income, diluted net (loss) income per share would be calculated assuming the impact of the conversion of the 2023 Notes, the exercise of outstanding equity compensation awards, ordinary shares expected to be issued under our ESPP and the exercise of contingent consideration warrants, all of which have been exercised or have expired during the first quarter of 2018.

We have a choice to settle the conversion obligation under the 2023 Notes in cash, shares or any combination of the two. We utilize the if-converted method to reflect the impact of the conversion of the 2023 Notes, unless the result is anti-dilutive. This method assumes the conversion of the 2023 Notes into shares of our ordinary shares and reflects the elimination of the interest expense related to the 2023 Notes.

The dilutive effect of the warrants, stock options, RSU’s and ordinary shares expected to be issued under our ESPP has been calculated using the treasury stock method.

A reconciliation of basic and diluted net (loss) income per share, together with the related shares outstanding in thousands for the years ended December 31, 2019, 2018 and 2017, is as follows:



Net (Loss) Income Per Share:	2019			2018			2017

Net (loss) income	$	(33,226	)	$	(95,304	)	$	68,271

Weighted average shares:
Basic shares	37,403			37,325			40,465
Effect of dilutive securities—employee and director equity awards outstanding and 2023 Notes	—			—			1,300
Diluted shares	37,403			37,325			41,765

Net (loss) income per share - basic	$	(0.89	)	$	(2.55	)	$	1.69
Net (loss) income per share - diluted	$	(0.89	)	$	(2.55	)	$	1.63

Potential ordinary shares of 16,740, 17,529, and 6,368 were excluded from the calculation of weighted average shares for the years ended December 31, 2019, 2018 and 2017, respectively, because their effect was considered to be anti-dilutive. For the years ended December 31, 2019 and 2018, the effects of dilutive securities were entirely excluded from the calculation of net (loss) income per share as a net loss was reported in these periods.