v3.10.0.1
Warrants (Tables)
6 Months Ended
Jun. 30, 2018
Schedule of warrants activity
Warrants outstanding and exercisable are summarized as follows:
 
 
 
Shares(1)
 
Weighted
Average
Exercise
Price
 
Range of
Exercise Prices
Outstanding at December 31, 2017
904,470

 
$
5.27

 
$2.20-$21.00
Exercised

 

 
Expired
(6,920
)
 
6.25

 
Outstanding at June 30, 2018
897,550

 
$
5.26

 
$2.20-$21.00
Exercisable at June 30, 2018
897,550

 
$
5.26

 
$2.20-$21.00
 
 
(1) Outstanding and exercisable information includes 15,000 equity-classified warrants.

Black Scholes  
Schedule of Share Based Payment Award Warrants Valuation Assumptions
The assumptions used in the Black-Scholes option-pricing model to estimate the fair value of the warrant liability as of June 30, 2018 were as follows:
 
 
Expected volatility
96.1% - 104.9%
Risk-free interest rate
2.38% - 2.65%
Dividend yield
Expected life in years
1.26 - 3.46

Monte Carlo Simulation Model  
Schedule of Share Based Payment Award Warrants Valuation Assumptions
The assumptions used in the Monte Carlo simulation model to estimate the fair value of the warrant liability as of June 30, 2018 were as follows:
 
 
Expected volatility
13.2% - 101.9%
Risk-free interest rate
0.18% - 2.4%
Dividend yield
Expected life in years
0.01 - 1.36