Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2020

Stockholders' Equity

Summary of restricted stock award activity

The following table summarizes restricted stock award activity for the nine months ended September 30, 2020:

		Weighted Average
	Number of	Grant Date Fair
	Shares	Value
Non-vested at December 31, 2019	3,303,839	$	4.29
Granted	1,107,340		2.39
Vested	(397,980)		4.31
Non-vested at September 30, 2020	4,013,199	$	3.77

Summary of stock option award activity

The following table summarizes stock option award activity for the nine months ended September 30, 2020:

				Weighted Average
				Remaining
		Weighted Average		Contractual Life
	Stock Options	Exercise Price		(in years)
Outstanding as of December 31, 2019	160,000	$	3.64	8.56
Granted	60,000		2.04
Outstanding as of September 30, 2020	220,000	$	3.20	8.29

Summary of warrant activities

A summary of warrant activities for the nine months ended September 30, 2020 is presented below:

				Weighted Average
				Remaining
		Weighted Average		Contractual Life
	Warrants	Exercise Price		(in years)
Outstanding as of December 31, 2019	4,207,447	$	6.81	1.25
Exercised	(102,742)		0.13
Expired	(880,250)		7.00
Outstanding as of September 30, 2020	3,224,455	$	6.97	0.19

Summary of stock-based compensation expense

The following table summarizes stock-based compensation expense for the three and nine  months ended September 30, 2020 and 2019 ($ in thousands):

	For the three months ended September 30,				For the nine months ended September 30,
	2020		2019		2020		2019
Research and development	$	157	$	179	$	462	$	559
General and administrative		568		654		1,633		1,885
Total stock-based compensation expense	$	725	$	833	$	2,095	$	2,444