Annual report pursuant to Section 13 and 15(d)

Stock and Employee Benefit Plans (Tables)

v3.19.1
Stock and Employee Benefit Plans (Tables)
 12 Months Ended
Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]  
Schedule of Fair Value Assumptions
The fair value of shares expected to be purchased under the 2018 ESPP using the Black-Scholes model with the following assumptions:
 
 
Years Ended December 31,
 
 
2018
Risk free interest rate
 
2.48
%
Expected term (in years)
 
0.5

Dividend yield
 
—

Expected volatility
 
57.57
%
The Company estimates the fair value of each stock award on the grant date using the Black-Scholes option-pricing model based on the following assumptions:
 
 
Years Ended December 31,
 
 
2018
 
2017
Risk free interest rate
 
2.40% - 3.06%

 
1.77% - 2.22%

Expected term (in years)
 
4.75 - 5.73

 
5.00 - 5.73

Dividend yield
 
—

 
—

Expected volatility
 
77.1% - 80.5%

 
75.1% - 78.9%

Schedule of Stock Option Activity
The following table summarizes stock option activity for these inducement options (in thousands):
 
Number of
Options
 
Weighted-
Average
Exercise
Price
 
Weighted-
Average
Remaining
Contractual
Life
 
Aggregate
Intrinsic
Value
(in thousands)
Outstanding, December 31, 2017
1,531,250

 
$
3.62

 
 
 
$
6,015

Exercised
(406,250
)
 
$
1.45

 
 
 
$
2,530

Outstanding, December 31, 2018
1,125,000

 
$
4.41

 
7.75 years
 
$
—

Vested or expected to vest
950,000

 
$
4.14

 
7.57 years
 
$
—

Exercisable, December 31, 2018
590,625

 
$
3.94

 
7.26 years
 
$
—

The following table summarizes stock option activity for employees and nonemployees:
 
Number of
Options
 
Weighted-
Average
Exercise
Price
 
Weighted-
Average
Remaining
Contractual
Life
 
Aggregate
Intrinsic
Value
(in thousands)
Outstanding, December 31, 2017
5,443,485

 
$
2.33

 
 
 
$
27,822

Granted
1,881,660

 
7.59

 
 
 
—

Exercised
(190,019
)
 
2.09

 
 
 
861

Canceled
(285,079
)
 
3.28

 
 
 
519

Outstanding, December 31, 2018
6,850,047

 
$
3.76

 
7.68 years
 
$
3,257

Vested or expected to vest, December 31, 2018
6,850,047

 
$
3.76

 
7.68 years
 
$
3,257

Exercisable, December 31, 2018
3,796,264

 
$
2.31

 
6.82 years
 
$
2,522

Schedule of Stock-Based Compensation Expense
Total stock-based compensation expense is recorded in operating expenses based upon the functional responsibilities of the individuals holding the respective options as follows (in thousands):
 
 
Years Ended December 31,
 
 
2018
 
2017
Research and development
 
$
1,984

 
$
844

General and administrative
 
2,959

 
2,202

Total stock-based compensation
 
$
4,943

 
$
3,046