Annual report pursuant to Section 13 and 15(d)

Stock Plan and Stock-Based Compensation (Tables)

v3.10.0.1
Stock Plan and Stock-Based Compensation (Tables)
12 Months Ended
Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]  
Summary of Stock Option Grants, Including Performance Options

The following table summarizes activity in the Company’s stock option grants, including performance options:

 

 

 

Shares

Subject to

Outstanding

Options

 

 

Weighted

Average

Exercise

Price of

Options

 

 

Weighted

Average

Remaining

Contractual

Term

(Years)

 

 

Aggregate

Intrinsic

Value (in thousands)

 

Outstanding as of December 31, 2017

 

 

4,356,441

 

 

$

5.15

 

 

 

 

 

 

 

 

 

Options granted

 

 

2,167,272

 

 

 

11.84

 

 

 

 

 

 

 

 

 

Options exercised

 

 

(750,852

)

 

 

4.76

 

 

 

 

 

 

 

 

 

Options forfeited

 

 

(179,729

)

 

 

8.81

 

 

 

 

 

 

 

 

 

Outstanding as of December 31, 2018

 

 

5,593,132

 

 

$

7.68

 

 

 

8.04

 

 

$

11,096

 

Vested and expected to vest as of

   December 31, 2018

 

 

5,593,132

 

 

 

7.68

 

 

 

8.04

 

 

 

11,096

 

Exercisable as of December 31, 2018

 

 

2,627,819

 

 

$

5.65

 

 

 

7.07

 

 

$

7,799

 

Summary of Stock-Based Compensation Expense

Stock-based compensation expense is included in the consolidated statements of operations and comprehensive loss and is as follows (in thousands):

 

 

 

Year Ended

 

 

 

December 31,

 

 

 

2018

 

 

2017

 

 

2016

 

Research and development

 

$

2,760

 

 

$

1,301

 

 

$

995

 

General and administrative

 

 

4,253

 

 

 

3,619

 

 

 

1,478

 

Total stock-based compensation expense

 

$

7,013

 

 

$

4,920

 

 

$

2,473

 

Estimated Weighted-Average Grant Date Fair Value

The following table presents the weighted-average assumptions the Company used in the Black-Scholes option-pricing model to derive the grant date fair values of stock options and performance-based stock options granted in each of the years presented along with the resulting estimated weighted-average grant date fair values per share:

 

 

 

Year Ended

December 31,

 

 

 

2018

 

 

2017

 

 

2016

 

Expected term

 

 

 

 

 

 

 

 

 

 

 

 

Options

 

6.2 yrs

 

 

6.0 yrs

 

 

6.1 yrs

 

Performance options

 

 

 

 

 

 

 

5.1 yrs

 

Expected volatility

 

 

 

 

 

 

 

 

 

 

 

 

Options

 

 

77

%

 

 

84

%

 

 

80

%

Performance options

 

 

 

 

 

 

 

 

85

%

Risk-free interest rate

 

 

 

 

 

 

 

 

 

 

 

 

Options

 

 

2.62

%

 

 

2.15

%

 

 

1.57

%

Performance options

 

 

 

 

 

 

 

 

1.56

%

Expected dividend yield

 

 

 

 

 

 

 

 

 

 

 

 

Options

 

 

 

 

 

 

 

 

 

Performance options

 

 

 

 

 

 

 

 

 

Weighted-average grant date fair value per share

 

 

 

 

 

 

 

 

 

 

 

 

Options

 

$

8.14

 

 

$

3.36

 

 

$

0.89

 

Performance options

 

 

 

 

 

 

 

 

1.20