Annual report pursuant to Section 13 and 15(d)

Stock-based Compensation (Tables)

v3.20.4
Stock-based Compensation (Tables)
12 Months Ended
Dec. 31, 2020
Share-based Payment Arrangement [Abstract]  
Schedule of Stock-based Compensation Expense
Stock-based compensation expense is included in the consolidated statements of operations as follows (in thousands): 
  Year Ended December 31,
  2020 2019 2018
Research and development $ 1,620  $ 1,562  $ 2,055 
Selling, general and administrative 6,108  5,381  5,834 
Total $ 7,728  $ 6,943  $ 7,889 

The following table presents total stock-based compensation expense by security type included in the consolidated statements of operations (in thousands):
  Year Ended December 31,
  2020 2019 2018
Stock options $ 2,381  $ 2,149  $ 1,975 
RSUs and RSAs 2,231  1,805  1,770 
PSUs 1,160  1,087  1,511 
PBOs 1,956  1,902  2,633 
Total $ 7,728  $ 6,943  $ 7,889 
Assumptions Used to Estimate the Fair Value of Option Grants The following summarizes the weighted-average assumptions used to estimate the fair value of employee and non-employee stock options granted:
  Year Ended December 31,
  2020 2019 2018
Expected life (years) 5.3 5.6 5.6
Volatility 50.4  % 55.3  % 60.0  %
Risk-free interest rate 1.0  % 2.4  % 2.7  %
Expected dividend yield 0.0  % 0.0  % 0.0  %
The following summarizes the weighted-average assumptions used to estimate the fair value of 76,000 shares of stock options granted to non-employees during the year ended December 31, 2020 for services valued at $0.4 million:
Expected life (years) 5.4
Volatility 51.6  %
Risk-free interest rate 0.4  %
Expected dividend yield 0.0  %
Schedule of Share-based Compensation, Stock Options, Activity
The following tables summarizes stock option activities:
Number
of
Shares
Weighted
Average
Exercise Price Per Share
(In Thousands)
Outstanding at December 31, 2017 4,579 $ 4.40 
Granted
645 $ 9.56 
Exercised
(772) $ 5.56 
Forfeited/Expired
(340) $ 6.66 
Outstanding at December 31, 2018 4,112 $ 4.81 
Granted 406 $ 20.68 
Exercised (1,045) $ 4.50 
Forfeited/Expired (326) $ 11.01 
Outstanding at December 31, 2019 3,147 $ 6.31 
Granted 496 $ 13.30 
Exercised (210) $ 6.30 
Forfeited/Expired (48) $ 16.71 
Outstanding at December 31, 2020 3,385 $ 7.19 

Number
of
Shares
Weighted
Average
Exercise Price Per Share
Weighted
Average
Remaining
Contractual Term
Aggregate Intrinsic
Value
(In Thousands) (In Years) (In Thousands)
Outstanding at December 31, 2020 3,385  $ 7.19  5.4 $ 49,542 
Exercisable at December 31, 2020 2,569  $ 5.09  4.3 $ 42,998 
Vested and expected to vest at December 31, 2020 3,279  $ 6.96  5.3 $ 48,786 
Schedule of Share-based Compensation, RSA Activity
The following table summarizes RSA activities:
Number
of
Shares
Weighted Average
Grant Date
Fair Value
Per Share
Non-vested balance at December 31, 2017 159 $ 4.68 
Granted
47 $ 14.35 
Vested
(151) $ 4.71 
Non-vested balance at December 31, 2018 55 $ 12.83 
Granted 40 $ 17.18 
Vested (56) $ 12.83 
Forfeited/Expired (4) $ 17.18 
Non-vested balance at December 31, 2019 35 $ 17.18 
Granted 96 $ 11.44 
Vested (35) $ 17.18 
Non-vested balance at December 31, 2020 96 $ 11.44 
Schedule of Share-based Compensation, RSU Activity
The following table summarizes RSU activities:
Number
of
Shares
Weighted Average
Grant Date
Fair Value
Per Share
(In Thousands)
Non-vested balance at December 31, 2017 560 $ 4.08 
Granted
86 $ 10.56 
Vested
(290) $ 4.09 
Forfeited/Expired
(8) $ 4.73 
Non-vested balance at December 31, 2018 348 $ 5.66 
Granted 72 $ 19.19 
Vested (210) $ 5.03 
Forfeited/Expired (9) $ 13.60 
Non-vested balance at December 31, 2019 201 $ 10.76 
Granted 156 $ 14.22 
Vested (168) $ 10.05 
Forfeited/Expired (13) $ 15.16 
Non-vested balance at December 31, 2020 176 $ 14.17 
Share-based Compensation, Performance Shares Award Outstanding Activity
The following table summarizes PSU activities:
Number
of
Shares
Weighted Average
Grant Date
Fair Value
Per Share
(In Thousands)
Non-vested balance at December 31, 2017 429 $ 4.20 
Granted
306 $ 6.71 
Vested
(495) $ 7.16 
Non-vested balance at December 31, 2018 240 $ 7.48 
Granted 95 $ 14.98 
Vested (200) $ 6.58 
Forfeited/Expired
(15) $ 15.58 
Non-vested balance at December 31, 2019 120 $ 13.88 
Granted 124 $ 13.59 
Vested (107) $ 11.28 
Forfeited/Expired
(6) $ 21.80 
Non-vested balance at December 31, 2020 131 $ 15.34 
The following tables summarizes PBO activities:
Number of Shares Weighted Average Grant Date Fair Value Per Share
(in thousands)
Outstanding at December 31, 2017 1,720 $ 2.54 
Granted
1,200 $ 5.02 
Exercised (84) $ 2.54 
Forfeited (1,254) $ 3.73 
Outstanding at December 31, 2018 1,582 $ 3.47 
Granted
718 $ 11.44 
Exercised
(422) $ 3.17 
Forfeited
(618) $ 10.34 
Outstanding at December 31, 2019 1,260 $ 4.75 
Granted
689 $ 6.37 
Forfeited
(389) $ 6.42 
Outstanding at December 31, 2020 1,560 $ 5.05 

Number
of
Shares
Weighted
Average
Exercise Price Per Share
Weighted
Average
Remaining
Contractual Term
Aggregate Intrinsic
Value
(In Thousands) (In Years) (In Thousands)
Exercisable at December 31, 2020 1,156  $ 7.55  6.6 $ 16,504 
Vested and expected to vest at December 31, 2020 1,510  $ 9.54  7.2 $ 18,567 
Schedule of Assumptions Used The following summarize the ranges of weighted-average assumptions used to estimate the fair value of employee stock options granted:
  Year Ended December 31,
  2020 2019 2018
Expected life (years) 5.3 5.6 5.6
Volatility 49.9  % 55.8  % 60.3  %
Risk-free interest rate 1.3  % 2.5  % 2.7  %
Expected dividend yield 0.0  % 0.0  % 0.0  %