STOCKHOLDERS' EQUITY (Tables)

9 Months Ended

Sep. 30, 2019

Equity [Abstract]

Summary of Common Stock

In addition, the Company had reserved for issuance the following amounts of shares of its common stock for the purposes described below as ofSeptember 30, 2019andDecember 31, 2018(in thousands):

	September 30, 2019	December 31, 2018
Shares of common stock issued	101,268	77,456
Shares of common stock reserved for issuance for:
Warrants to purchase common stock	26,307	9,258
Stock options	6,450	3,942
Shares available for grant under 2014 Stock Incentive Plan	8,599	2,001
Shares available for sale under 2014 Employee Stock Purchase Plan	28	38
Total shares of common stock issued and reserved for issuance	142,652	92,695

Summary of Warrants Outstanding and Warrant Activity

The following table sets forth the Company's warrant activity for the nine months ended September 30, 2019 (in thousands):

			Year-to-Date Warrant Activity
Issued	Exercise Price	Expiration	December 31, 2018	Issued	(Exercised)		September 30, 2019
Jun-2019	$1.47	Jun-2020	—	20,410	—		20,410
Mar-2018	$1.20	Mar-2023	7,211	—	(1,861	)	5,350
Nov-2017	$0.80	Nov-2022	1,992	—	(1,500	)	492
May-2015	$11.83	Nov-2024	28	—	—		28
Nov-2014	$11.04	Nov-2024	27	—	—		27
			9,258	20,410	(3,361	)	26,307

The following table sets forth the Company's warrant activity subsequent to September 30, 2019 which resulted from the exercises and modifications described below:

			Subsequent Event Warrant Activity
Issued	Exercise Price	Expiration	September 30, 2019	(Exercised)		October 31, 2019
Jun-2019	$1.47	Jun-2020	20,410	—		20,410
Mar-2018	$0.95*	Mar-2023	5,350	(3,407	)	1,943
Nov-2017	$0.55*	Nov-2022	492	(5	)	487
May-2015	$11.83	Nov-2024	28	—		28
Nov-2014	$11.04	Nov-2024	27	—		27
			26,307	(3,412	)	22,895

* Exercise price shown (i) reflects modification described below and (ii) subject to further adjustment based on down round provision added by amendment described below.