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Stock-based awards (Tables)
6 Months Ended
Jun. 30, 2019
Stock-based awards  
Schedule of assumptions used to determine grant-date fair value of stock options granted

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Three Months Ended

 

Six Months Ended

 

 

June 30, 

 

June 30, 

 

    

2019

    

2018

    

2019

    

2018

Expected term (in years)

 

 

6.07

 

n/a

 

 

6.04

 

n/a

Volatility

 

 

71.20

%  

n/a

 

 

69.80

%  

n/a

Risk-free interest rate

 

 

2.28

%  

n/a

 

 

2.39

%  

n/a

Dividend yield

 

 

0.00

%  

n/a

 

 

0.00

%  

n/a

Weighted average fair value of common stock

 

$

9.72

 

n/a

 

$

8.26

 

n/a

 

Summary of stock option activity

 

 

 

 

 

 

 

 

 

 

 

 

    

    

    

Weighted-

    

Weighted-

    

    

 

 

 

 

 

Average

 

Average

 

 

 

 

 

 

 

Exercise

 

remaining

 

Aggregate

 

 

Number

 

Price per

 

contractual

 

Intrinsic

 

 

of Options

 

Share

 

term (years)

 

Value

Balance Outstanding, December 31, 2018

 

1,839,913

 

$

0.61

 

9.74

 

$

10,577

Options granted

 

1,228,352

 

$

7.61

 

  

 

 

  

Options exercised

 

(647,757)

 

$

0.62

 

  

 

 

  

Balance Outstanding, June 30, 2019

 

2,420,508

 

$

4.17

 

9.48

 

$

36,271

Exercisable, June 30, 2019

 

23,691

 

$

4.17

 

9.42

 

$

352

Vested and expected to vest, June 30, 2019

 

2,420,508

 

$

4.29

 

9.48

 

$

36,271