Stockholders' Equity

9 Months Ended

Sep. 30, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Warrants

As of September 30, 2017, the following warrants for common stock were issued and outstanding:



Issue date	Expiration date	Exercise price		Number of warrants outstanding
January 11, 2017	None	$	0.001	7,258,263
November 21, 2012	November 21, 2017	$	7.86	695,383

Refer to footnote 11 for further detail of the warrants issued in January 2017.

During the three and nine months ended September 30, 2017, no warrants were exercised. During the three months ended September 30, 2016, no warrants were exercised. During the nine months ended September 30, 2016, warrants for 419,244 shares of the Company's common stock were exercised via cashless exercises and 313,756 shares were exercised for cash generating proceeds of $2.1 million. The Company issued a total of 603,545 shares of common stock in connection with the exercise of such warrants for the same period.

During the quarter ended September 30, 2017 the Company received proceeds totaling $2.1 million related to a warrant exercise of November 21, 2012 warrants. The warrant exercise was effective in early October 2017 and resulted in the issuance of 267,966 shares of common stock.

Stockholders' Equity

Sale of Common Stock

In January 2017, the Company sold 5,002,702 million shares of its common stock at a public offering price of $5.60 per share and sold warrants to purchase up to 7,258,263 shares of its common stock at a public offering price of $5.599 per warrant share. The public offering price for the warrants was equal to the public offering price of the common stock, less the $0.001 per share exercise price of each warrant. After deducting underwriter discounts and offering expenses, the Company received net proceeds from the transaction of $66.8 million. These warrants were recorded as a component of stockholders’ equity within additional paid-in capital. Per their terms, the outstanding warrants to purchase shares of common stock may not be exercised if the holder’s ownership of the Company’s common stock would exceed 19.99 percent following such exercise.

Share-based Compensation

Total share-based compensation expense by statement of operations is presented below (in thousands):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Research and development expense	$	584	$	1,361	$	2,504	$	4,297
General and administrative expense	895		1,399		2,964		3,789
	$	1,479	$	2,760	$	5,468	$	8,086

During the three and nine months ended September 30, 2017, 7,937 shares were issued pursuant to stock option exercises, generating net proceeds of $0.04 million. During the three months ended September 30, 2016, no shares were issued pursuant to stock option exercises. During the nine months ended September 30, 2016, 22,132 shares were issued pursuant to stock option exercises, generating net proceeds of $0.2 million.