11.Stock-based compensation

Stock-based compensation expense is measured on the grant date based on the fair value of the award. Stock-based compensation expense is recognized on a straight-line basis over the requisite service period for awards expected to vest. The estimated grant date fair value of stock options was determined using a Black-Scholes valuation model using the following weighted-average assumptions for the periods indicated:

​

​

The Company granted 61 and 248 stock options during the 39 weeks ended October 30, 2021 and October 31, 2020, respectively. Stock-based compensation expense for stock options was $2,712 and $2,900 for the 13 weeks ended October 30, 2021 and October 31, 2020, respectively. Stock-based compensation expense for stock options was $8,710 and $8,247 for the 39 weeks ended October 30, 2021 and October 31, 2020, respectively. The weighted-average grant date fair value of these stock options was $109.72 and $54.40 for the 39 weeks ended October 30, 2021 and October 31,

2020, respectively. At October 30, 2021, there was approximately $14,108 of unrecognized stock-based compensation expense related to unvested stock options.

There were 60 and 161 restricted stock units issued during the 39 weeks ended October 30, 2021 and October 31, 2020, respectively. Stock-based compensation expense for restricted stock units was $4,622 and $5,098 for the 13 weeks ended October 30, 2021 and October 31, 2020, respectively. Stock-based compensation expense for restricted stock units was $14,606 and $14,446 for the 39 weeks ended October 30, 2021 and October 31, 2020, respectively. At October 30, 2021, there was approximately $27,111 of unrecognized stock-based compensation expense related to restricted stock units.

There were 46 performance-based restricted stock units issued during the 39 weeks ended October 30, 2021. The Company did not issue any performance-based restricted stock units during the 39 weeks ended October 31, 2020. Stock-based compensation expense for performance-based restricted stock units was $1,786 and $386 for the 13 weeks ended October 30, 2021 and October 31, 2020, respectively. Stock-based compensation expense for performance-based restricted stock units was $4,901 and $286 for the 39 weeks ended October 30, 2021 and October 31, 2020, respectively. At October 30, 2021, there was approximately $15,898 of unrecognized stock-based compensation expense related to performance-based restricted stock units.

Awards with market conditions are classified as liability awards and the fair value is determined using a Monte Carlo simulation. Market-based restricted stock units were granted to the former CEO in fiscal 2018 and settled during the 39 weeks ended October 30, 2021. Compensation expense for liability awards was $3,289 and $198 for the 13 weeks ended October 30, 2021 and October 31, 2020, respectively. Compensation expense (benefit) for liability awards was $7,671 and ($331) for the 39 weeks ended October 30, 2021 and October 31, 2020, respectively. The total compensation expense for this award was $10,000 and 28 shares were settled during the 39 weeks ended October 30, 2021.