EARNINGS (LOSS) PER SHARE

Basic earnings (loss) per share is computed by dividing net income (loss) by the weighted average number of shares outstanding during the period. For periods in which the Company reports net income, diluted net income per share is determined by using the weighted average number of common and dilutive common equivalent shares outstanding during the period unless the effect is antidilutive.

The calculations of shares used to compute basic and diluted loss per share are as follows (in thousands):



	Year ended December 31,
	2019	2018	2017
Weighted average shares outstanding—basic	109,734	103,916	58,822
Potential dilutive common shares	—	—	—
Weighted average shares outstanding—diluted	109,734	103,916	58,822

Options to purchase the Company's common stock, unvested shares of restricted stock and unvested shares underlying performance-based stock grants aggregating 4.6 million shares for the year ended December 31, 2019 have not been included in the computation of diluted loss per share because their effect would have been antidilutive. Options to purchase the Company's common stock, unvested shares of restricted stock, unvested shares underlying performance-based stock grants and shares in connection with future purchases under the Company's Amended and Restated 2000 Employee Stock Purchase Plan, as amended (the "ESPP"), aggregating 3.1 million shares for the year ended December 31, 2018 have not been included in the computation of diluted loss per share because their effect would have been antidilutive. Options to purchase the Company's common stock, unvested shares of restricted stock and unvested shares underlying performance-based stock grants aggregating 2.5 million shares for the year ended December 31, 2017 have not been included in the computation of diluted loss per share because their effect would have been antidilutive.