v3.20.2
Stockholders’ Equity and Stock-Based Compensation (Tables)
9 Months Ended
Sep. 30, 2020
Share-based Payment Arrangement [Abstract]  
Schedule of Warrant Activity
A summary of the Company’s warrant activity for the nine months ended September 30, 2020 was as follows:
Shares of Stock under WarrantsWeighted-
Average
Exercise
Price
Weighted-
Average
Remaining
Contractual
Term
Aggregate
Intrinsic
Value
Outstanding at January 1, 202024,406,000 $1.76 4.82$7,933,000 
Granted95,396,000 0.22 4.53
Exercised(90,093,000)0.21 37,150,000 
Canceled— 
Outstanding at September 30, 2020
29,709,000 $1.54 4.11$1,813,000 
Vested and exercisable at September 30, 2020
29,709,000 $1.54 4.11$— 
Summary of Stock Option Activity
A summary of the Company’s stock option activity under the Company's equity incentive plans for the nine months ended September 30, 2020 was as follows:   
Shares of Stock under Stock OptionsWeighted-
Average
Exercise
Price
Weighted-
Average
Remaining
Contractual
Term
Aggregate
Intrinsic
Value
Outstanding at January 1, 20201,743,000 $5.73 8.2$4,000 
Granted4,250,000 0.67 
Exercised— — $— 
Canceled(662,000)3.52 
Outstanding at September 30, 2020
5,331,000 $1.97 8.96$353,000 
Vested and exercisable at September 30, 2020
1,119,000 $5.10 7.31$— 
Summary of Recognized Stock-Based Compensation Expense
The Company recognized stock-based compensation expense for the periods presented were as follows: 
 Three Months Ended
September 30,
Nine Months Ended
September 30,
2020201920202019
Research and development$122,000 $59,000 $255,000 $169,000 
General and administrative325,000 305,000 848,000 821,000 
Total stock-based compensation expense$447,000 $364,000 $1,103,000 $990,000 
Schedule of Weighted-Average Assumptions in Black -Scholes Option Pricing Model
The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee stock option grants during the periods presented were as follows:
Three Months Ended
September 30,
Nine months Ended
September 30,
2020201920202019
Risk-free interest rate0.4 %1.8 %0.8 %2.4 %
Expected volatility77.9 %68.2 %74.8 %68.2 %
Expected term (in years)5.56.15.95.1
Expected dividend yield0.0 %0.0 %0.0 %0.0 %