Stock-Based Compensation Plan (Tables)

3 Months Ended

Mar. 31, 2020

Schedule of share-based payment award, stock options, valuation assumptions

The Company utilized the Black-Scholes valuation model for estimating the fair value of the stock options granted, with the following weighted-average assumptions for options granted in the three months ended March 31, 2020 and 2019, respectively:

	2020		2019
Risk-free interest rate	0.55	%	2.23	%
Expected volatility	123	%	126	%
Expected term in years	5.8		6.0
Dividend yield	—	%	—	%

Warrant [Member]

Schedule of share-based payment award, stock options, valuation assumptions

The following summary represents option activity under the Company’s stock-based compensation plans for the three months ended March 31, 2020:

		Weighted-
		Average
		Exercise
	Options	Price
	(in thousands)
Outstanding at December 31, 2019	68	$	68.56
Granted	99		4.79
Expired	(1)		28.54
Outstanding at March 31, 2020	166		30.66
Exercisable at March 31, 2020	34	$	111.43