Share-Based Compensation

6 Months Ended

Jun. 30, 2019

We utilize share-based compensation in the form of stock options, restricted stock, and restricted stock units. The following table summarizes the components of share-based compensation expense for the three and six months ended June 30, 2019 and 2018 (in thousands):



	Three Months Ended June 30,				Six Months Ended June 30,
	2019		2018		2019		2018
Research and development	$	50	$	341	$	174	$	381
General and administrative	195		1,627		619		1,734
Total share-based compensation expense	$	245	$	1,968	$	793	$	2,115

Total compensation cost related to non-vested awards not yet recognized and the weighted-average periods over which the awards were expected to be recognized at June 30, 2019 were as follows (in thousands):



	Stock Options		Restricted Stock
Unrecognized compensation cost	$	850	$	—
Expected weighted-average period in years of compensation cost to be recognized	2.04		0.00

Total fair value of shares vested and the weighted average estimated fair values of shares granted for the six months ended June 30, 2019 and 2018 were as follows (in thousands):



	Stock Options
	Six Months Ended June 30,
	2019		2018
Total fair value of shares vested	$	378	$	85
Weighted average estimated fair value of shares granted	$	3.18	$	2.41

Valuation Assumptions

The fair value of stock options and warrants at the date of grant was estimated using the Black-Scholes option pricing model. The expected volatility is based upon historical volatility of the Company’s stock. The expected term for the options is based upon observation of actual time elapsed between date of grant and exercise of options for all employees. The expected term for the warrants is based upon the contractual term of the warrants.