Stock-Based Compensation and Warrants

3 Months Ended

Mar. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

4.	Stock-Based Compensation and Warrants

For stock options requiring an assessment of value during the three months ended March 31, 2018, the fair value of each stock option award was estimated using the Black-Scholes option-pricing model utilizing the following assumptions:

		March 31, 2018
Risk-free interest rate		2.43 to 2.62%
Expected dividend yield		0%
Expected volatility		82.0-83.0%
Expected life		3.2 to 7.0 years

A summary of stock option activity for the three months ended March 31, 2018 is as follows:

	Number of Shares (in thousands)		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (in Years)
Stock options outstanding at December 31, 2017		2,732	$	4.07		5.76
Granted		25	$	16.65
Exercised		—	$	—
Cancelled		—	$	—
Stock options outstanding at March 31, 2018		2,757	$	4.18		5.52
Stock options exercisable at March 31, 2018		818	$	3.13		4.95

The Company recognized approximately $1,158,000 and $543,000 in stock-based compensation during the three months ended March 31, 2018 and 2017, respectively. As of March 31, 2018, total unrecognized stock-based compensation was approximately $10,219,000, which is expected to be recognized as an operating expense in the Company’s statement of operations through June 2022.

The intrinsic value of exercisable but unexercised in-the-money stock options at March 31, 2018 was approximately $8,941,000, based on a fair value of $14.05 per share on March 29, 2018.

Stock-based compensation for the three months ended March 31, 2018 and 2017 was included in the statement of operations as follows:

	March 31,
(in thousands)	2018		2017
General and administrative	$	380	$	227
Research and development		778		316
Total	$	1,158	$	543

The Company had approximately 1,252,000 of outstanding and exercisable common stock warrants at March 31, 2018. The intrinsic value of exercisable but unexercised in-the-money common stock warrants at March 31, 2018 was approximately $8,323,000 based on a fair value of $14.05 per share on March 29, 2018.