v3.21.1
Compensation Plans (Tables)
12 Months Ended
Dec. 31, 2020
Compensation Related Costs [Abstract]  
Disclosure of Share-based Compensation Arrangements by Share-based Payment Award The fair value of the stock option awards granted during the years ended December 31, 2020 and 2019 was determined on the grant date using the Black-Scholes valuation model based on the following ranges of weighted-average assumptions:
December 31, 2020 December 31, 2019
Expected volatility (1)
96% - 103%
85%
Expected dividend yield (2)
Expected term (3)
5.15 - 6.25 years
2.5 - 7.75 years
Risk-free interest rate (4)
0.23% - 1.72%
1.49% - 2.49%
(1)Expected volatility is based on the historical volatility of a selected peer group over a period equivalent to the expected term.
(2)We assumed a dividend yield of zero as management has no plans to declare dividends in the foreseeable future.
(3)Expected term represents the estimated period of time until an award is exercised and was determined using the simplified method.
(4)The risk-free rate is an interpolation of yields on U.S. Treasury securities with maturities equivalent to the expected term.
Schedule of Stock Option Activity
A summary of stock option activity for the years ended December 31, 2020 and 2019 is as follows:
Stock Options
Number of Options Weighted-Average
Exercise Price
Outstanding as of December 31, 2018 —  $ — 
Granted 654,284  9.28 
Exercised —  — 
Forfeited (24,511) 17.00 
Outstanding as of December 31, 2019 629,773  8.98 
Granted 949,126  3.72 
Exercised —  — 
Forfeited (204,927) 6.94 
Outstanding as of December 31, 2020 1,373,972  $ 5.47 
Share-based Payment Arrangement, Outstanding Award, Activity, Excluding Option The following table provides a summary of the unvested Common Units outstanding and related transactions:
Common Units
Subject to Vesting
Unvested Common Units as of December 31, 2018 775,979 
Granted 288,444 
Vested (235,756)
Forfeited (12,008)
Unvested Common Units as of December 31, 2019 816,659 
Granted — 
Vested (368,489)
Forfeited (244,266)
Unvested Common Units as of December 31, 2020 203,904