Net Loss per Share Attributable to Common Stockholders

9 Months Ended

Sep. 30, 2020

Earnings Per Share [Abstract]

Net Loss per Share Attributable to Common Stockholders

5. Net Loss per Share Attributable to Common Stockholders

Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding for the period. Because the Company has reported a net loss for all periods presented, diluted net loss per common share is the same as basic net loss per common share for those periods. The following table summarizes the computation of basic and diluted net loss per share attributable to common stockholders of the Company:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2020			2019			2020			2019
	(In thousands, except share and per share data)						(In thousands, except share and per share data)
Numerator—basic and diluted:
Net loss	$	(20,437	)	$	(12,829	)	$	(52,735	)	$	(42,047	)
Deemed dividend due to warrant reset		—			—			(3,906	)		—
Net loss attributable to common    stockholders—basic and diluted	$	(20,437	)	$	(12,829	)	$	(56,641	)	$	(42,047	)
Net loss per share attributable to common    stockholders—basic and diluted	$	(0.46	)	$	(0.41	)	$	(1.43	)	$	(1.40	)
Denominator—basic and diluted:
Weighted-average number of common shares    used to compute net loss per share attributable    to common stockholders—basic and diluted		44,156,808			31,630,639			39,714,490			30,103,338

The following potentially dilutive securities have been excluded from the computation of diluted weighted-average shares outstanding because such securities have an antidilutive impact due to losses reported (in common stock equivalent shares):

	September 30,
	2020		2019
Options to purchase common stock		6,770,660		6,053,654
Warrants to purchase common stock		689,242		4,595,039
Employee Stock Purchase Plan		18,838		15,223
Non-vested restricted stock units (RSUs)		18,500		—

   As discussed in Note 13, in March 2019, the Company sold 2,095,039 shares of common stock as well as 2,500,000 pre-funded warrants and 4,595,039 Series 1 and Series 2 warrants. The pre-funded warrants are exercisable into shares of common stock for $0.0001 per share. In January 2020, the Company sold 3,036,719 shares of common stock as well as 1,338,287 pre-funded warrants. The warrants are exercisable into shares of common stock for $0.0001 per share. The shares of common stock into which the pre-funded warrants may be exercised are considered outstanding for the purposes of computing earnings per share. As of September 30, 2020, there were 5,557,952 pre-funded warrants outstanding.

In May 2020, a holder of pre-funded warrants exchanged 280,335 warrants for 280,332 shares of common stock in a cashless exercise. Additionally, in May 2020, holders of Series 1 and Series 2 warrants, exercised 3,489,131 warrants and received 1,512,229 shares of common stock in a cashless exercise. In August 2020, a holder of Series 1 and Series 2 warrants, exercised 416,666 warrants in exchange of 130,151 shares of common stock in a cashless exercise.

As of September 30, 2020, there were 344,620 shares of our common stock issuable upon the exercise of Series 1 warrants outstanding, at an exercise price of $10.00 per share, and there were 344,622 shares of our common stock issuable upon the exercise of Series 2 warrants outstanding, at an exercise price of $13.00 per share.