Basic and Diluted Net Loss per Common Share

The following table provides a reconciliation of the numerator and denominator used in computing basic and diluted net loss attributable to common stockholders per common share:



(in thousands, except per share amounts)	Years Ended December 31,
Historical	2018			2017			2016
Numerator:
Net loss attributable to common stockholders	$	(348,995	)	$	(284,002	)	$	(200,042	)
Denominator:
Weighted average common shares outstanding — basic and diluted	185,790,021			153,355,144			134,401,588

Dilutive common stock equivalents would include the dilutive effect of common stock options, convertible debt units, RSUs and warrants for common stock equivalents. Potentially dilutive common stock equivalents were excluded from the diluted earnings per share denominator for all periods because of their anti-dilutive effect. For the year ended 2018 there was 40.9 million potential common shares outstanding as a result of the convertible debt that was excluded from the diluted net loss per share calculation because their effect would have been anti-dilutive.

The table below presents potential shares of common stock that were excluded from the computation as they were anti-dilutive using the treasury stock method:



	Year ended December 31,
(in thousands)	2018	2017	2016
Options to purchase common stock	15,810	15,181	15,528
Convertible debt	40,850	40,850	40,850
Outstanding warrants, convertible to common stock	2,657	3,110	3,110
Unvested restricted stock units	3,712	2,575	744
Vested restricted stock units, unissued	91	50	—
Total number of potentially issuable shares	63,120	61,766	60,232