3. Earnings Per Share

Basic earnings per common stock are computed by dividing net loss attributable to common stockholders by the weighted average number of common stock outstanding during the reporting period. Diluted earnings per share reflects the potential dilution that could occur if securities or other contracts to issue common stock (such as stock options, unvested restricted stock, common stock warrants, and preferred stock) were exercised or converted into common stock or resulted in the issuance of common stock (net of any assumed repurchases) that then shared in the earnings of the Company, if any. This is computed by dividing net earnings by the combination of dilutive common stock equivalents, which is comprised of shares issuable under outstanding warrants, the conversion of preferred stock, and the Company’s share-based compensation plans, and the weighted average number of common stock outstanding during the reporting period. Since the Company is in a net loss position, all common stock equivalents would be considered to be anti-dilutive and are, therefore, not included in the determination of diluted earnings per share. Accordingly, basic and diluted loss per share are the same.

The following table provides the components of the calculations of basic and diluted earnings per share (in thousands, except share amounts):


	Year ended December 31,
	2019		2018			2017
Numerator:
Net loss attributable to common stockholders	$	(85,517)	$	(78,167)	$	(130,178)
Denominator:
Weighted average number of common stock outstanding		237,152,780		218,882,337		216,343,985

The dilutive potential shares common stock are summarized as follows:


	At December 31,
	2019	2018	2017
Stock options outstanding (1)	23,013,590	21,957,150	19,872,029
Restricted stock outstanding (2)	4,608,560	2,347,347	234,744
Common stock warrants (3)	110,573,392	115,824,142	115,824,242
Preferred stock (4)	2,998,527	17,933,591	2,782,075
Convertible Senior Notes (5)	59,133,896	43,630,020	-
Number of dilutive potential shares of common stock	200,327,965	201,692,250	138,713,090

(1)

During the years ended December 31, 2019, 2018, and 2017, the Company granted 3,221,892, 2,679,667, and 5,485,863 stock options, respectively.

(2)

During the years ended December 31, 2019, 2018, and 2017, the Company granted 3,201,892, 2,367,347, and 234,744 shares of restricted stock, respectively.

(3)

In April 2017, the Company issued 5,250,750 warrants with an exercise price of $2.69 per warrant, as described in Note 11, Stockholders’ Equity. Of these warrants issued in April 2017, all have been exercised as of December 31, 2019.

In April 2017, the Company issued warrants to acquire up to 55,286,696 of the Company’s common stock as part of a transaction agreement with Amazon, subject to certain vesting events, as described in Note 13, Warrant Transaction Agreements. Of these warrants issued, none have been exercised as of December 31, 2019.

In July 2017, the Company issued warrants to acquire up to 55,286,696 of the Company’s common stock as part of a transaction agreement with Walmart, subject to certain vesting events, as described in Note 13, Warrant Transaction Agreements. Of these warrants issued, none have been exercised as of December 31, 2019.

(4)

The preferred stock amount represents the dilutive potential shares of common stock of the Series C, D and E redeemable convertible preferred stock, based on the conversion price of the preferred stock as of December 31, 2019, 2018 and 2017, respectively. Of the 10,431 Series C redeemable preferred stock issued on May 16, 2013, 7,811 had been converted to common stock through December 31, 2017, with the remainder still outstanding. Of the 18,500 Series D redeemable convertible preferred stock issued on December 22, 2016, 3,700 shares have been redeemed and the remaining 14,800 have been converted to common stock during the year ended December 31, 2017. On November 1, 2018, the Company issued 35,000 shares of Series E redeemable convertible preferred stock. As of December 31, 2019, 30,462 of the Series E Preferred Stock had been converted to common stock and 4,038 were redeemed for cash. The remainder of 500 were converted in January 2020.

(5)

In March 2018, the Company issued $100.0 million in aggregate principal amount of 5.5% Convertible Senior Notes. In September 2019, the Company issued a $40.0 million in aggregate principal amount of 7.5% Convertible Senior Note. See Note 10, Convertible Senior Notes.