XML 50 R32.htm IDEA: XBRL DOCUMENT v3.24.0.1
Stock-based compensation (Tables)
12 Months Ended
Dec. 31, 2023
Stock-based compensation  
Compensation cost recognized for all stock-based compensation awards

Year ended December 31, 

 

    

2023

    

2022

    

2021

 

(in thousands)

 

General and administrative

$

7,568

$

6,398

$

7,191

Research and development

 

3,585

 

2,946

 

4,133

Total stock-based compensation expense

$

11,153

$

9,344

$

11,324

Summary of stock-based compensation expense by type of award

Year ended December 31, 

2023

    

2022

    

2021

(in thousands)

Stock options

$

7,627

$

5,938

$

7,438

Restricted stock awards and units

3,241

3,215

3,551

Employee stock purchase plan awards

 

285

 

191

 

335

Total stock-based compensation expense

$

11,153

$

9,344

$

11,324

Summary of status and changes in unvested restricted stock

    

Weighted

Average

Grant Date

Fair Value

Units

    

Per Unit

Unvested restricted stock units as of December 31, 2022

1,112,563

$

5.27

Awarded

999,250

$

7.58

Vested

(531,560)

$

5.73

Forfeited

(209,356)

$

6.08

Unvested restricted stock units as of December 31, 2023

1,370,897

$

6.65

Summary of stock option activity

    

Weighted

    

Remaining

    

Aggregate

Average

Contractual

Intrinsic

Exercise

Life

Value

Shares

    

Price

    

(in years)

    

(in thousands)

Outstanding at December 31, 2022

6,199,571

$

8.12

 

Granted

2,326,800

$

8.58

Exercised

(385,655)

$

4.98

Cancelled or forfeited

(715,272)

$

7.86

Outstanding at December 31, 2023

7,425,444

$

8.52

7.3

11,293

Exercisable at December 31, 2023

3,823,420

$

9.43

 

5.9

$

6,020

Summary of weighted-average assumptions

Year ended December 31, 

    

2023

    

2022

    

2021

Risk-free interest rate

 

4.0

%  

 

2.2

%  

 

0.9

%

Expected dividend yield

 

%

 

%

 

%

Expected term (in years)

 

6.0

 

6.0

 

6.0

Expected volatility

 

80.4

%  

 

79.4

%  

 

75.0

%