9. Stockholders’ Equity (Tables)

3 Months Ended

Mar. 31, 2018

Stockholders Equity Tables

Stock option assumptions

The weighted average fair value of stock options granted during the periods and the assumptions used to estimate those values using the Black-Scholes option pricing mode were as follows:  

		Three Months Ended
		March 31,
		2018		2017
Weighted average expected
stock price volatility		86.4%		85.0%
Estimated dividend yield		-		-
Risk-free interest rate		2.7%		2.1%
Expected life of option (in years)		6.3		6.2
Weighted average grant date
fair value per option	$	1.83	$	1.86

Stock option activity

The following table shows the option activity, described above, during the three months ended March 31, 2018 (shares and intrinsic value in thousands):

				Weighted Average
			Average	Remaining		Aggregate
			Exercise	Contractual Life		Intrinsic
	Shares		Price	(years)		Value
Options Outstanding at December 31, 2017	1,042	$	13.80	8.8
Granted	336		2.46
Exercised	-		-
Cancelled	(62)		21.84
Expired	-		-
Options outstanding at March 31, 2018	1,316	$	10.53	8.9	$	3
Options vested and expected to vest as of March 31, 2018	850	$	14.51	8.6	$	2
Options vested and exercisable as of March 31, 2018	338	$	24.30	7.8	$	-

Restricted stock activity

The following table shows the Company's non-vested restricted stock activity during the three months ended March 31, 2018 (shares in thousands):

			Weighted Average
			Grant Date Fair
	Shares		Value
Non-vested restricted stock outstanding at December 31, 2017	135	$	3.17
Granted	62		2.46
Vested	(1)		2.19
Forfeited	-		-
Non-vested restricted stock outstanding at March 31, 2018	196	$	2.95