STOCKHOLDERS' EQUITY

12 Months Ended

Dec. 31, 2015

Stockholders' Equity Note [Abstract]

Stockholders' Equity

Common Stock

The following shares were reserved for future issuance:



	December 31,
	2015
Common stock options outstanding and available for future grant	3,354,541
Warrants to purchase common stock	1,428,383
Employee Stock Purchase Plan	267,355
	5,050,279

Sale of Common Stock

In February 2015, the Company completed a common stock offering whereby it issued an aggregate 2,587,500 shares of common stock at $20.00 per share. Proceeds from the common stock offering, net of underwriting discounts, commissions and offering expenses, were $48.4 million.

In September 2015, the Company completed an additional common stock offering whereby it issued an aggregate 2,250,000 shares of common stock at $45.00 per share. Proceeds from the common stock offering, net of underwriting discounts, commissions and offering expenses, were $94.9 million.

Warrants

The Company issued warrants in connection with private placements of common stock in April 2011 and November 2012. As of December 31, 2015 the following warrants for common stock were issued and outstanding:



Issue date	Expiration date	Exercise price		Number of warrants outstanding
April 4, 2011	April 4, 2016	$	6.74	733,000
November 21, 2012	November 21, 2017	$	7.86	695,383
				1,428,383

During the years ended December 31, 2015 and 2014, warrants for 1,037,330 and 73,964 shares of the Company's common stock were exercised via cashless exercises and the Company issued a total of 809,498 and 43,526 shares of common stock, respectively.