9. Loss Per Share

Basic and diluted loss per share attributable to common stockholders was calculated as follows:

	Year Ended December 31,
	2017			2016			2015
	(In thousands)
Net loss	$	(67,543	)	$	(31,634	)	$	(12,397	)
Weighted average shares outstanding, basic and diluted		36,006			22,222			243
Net loss per share attributable to common stockholders, basic and diluted	$	(1.88	)	$	(1.42	)	$	(51.02	)

In May 2016, the Company issued 6,900,000 shares of common stock in connection with its IPO and 23,481,956 shares of common stock in connection with the automatic conversion of its convertible preferred stock upon the closing of the IPO. In addition, the Company issued a total of 3,055,554 shares of common stock in two separate, concurrent private placements upon the closing of the IPO. The issuance of these shares resulted in a significant increase in the Company’s weighted average shares outstanding and has affected the year-over-year comparability of the Company’s (loss) earnings per share calculations throughout 2017.

On November 1, 2017, the Company entered into an underwriting agreement related to a public offering of 6,250,000 shares of the Company’s common stock, par value $0.0001 per share.

The following common stock equivalents were excluded from the calculation of diluted loss per share in 2017, 2016 and 2015 because their inclusion would have been anti-dilutive:

	Year Ended December 31,
	2017		2016		2015
	(In thousands)
Convertible preferred stock		-		-		21,363
Unvested restricted stock		480		1,362		1,945
Stock options		4,705		3,040		456
		5,185		4,402		23,764