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:

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The Company granted 61 and 248 stock options during the 26 weeks ended July 31, 2021 and August 1, 2020, respectively. Stock-based compensation expense for stock options was $3,101 and $2,872 for the 13 weeks ended July 31, 2021 and August 1, 2020, respectively. Stock-based compensation expense for stock options was $5,998 and $5,347 for the 26 weeks ended July 31, 2021 and August 1, 2020, respectively. The weighted-average grant date fair value of these stock options was $109.72 and $54.40 for the 26 weeks ended July 31, 2021 and August 1, 2020, respectively. At July 31, 2021, there was approximately $17,216 of unrecognized stock-based compensation expense related to unvested stock options.

There were 58 and 158 restricted stock units issued during the 26 weeks ended July 31, 2021 and August 1, 2020, respectively. Stock-based compensation expense for restricted stock units was $5,149 and $5,161 for the 13 weeks ended July 31, 2021 and August 1, 2020, respectively. Stock-based compensation expense for restricted stock units was $9,984 and $9,348 for the 26 weeks ended July 31, 2021 and August 1, 2020, respectively. At July 31, 2021, there was approximately $32,844 of unrecognized stock-based compensation expense related to restricted stock units.

There were 46 performance-based restricted stock units issued during the 26 weeks ended July 31, 2021. The Company did not issue any performance-based restricted stock units during the 26 weeks ended August 1, 2020. Stock-based compensation expense for performance-based restricted stock units was $1,869 and $380 for the 13 weeks ended July 31, 2021 and August 1, 2020, respectively. Stock-based compensation expense for performance-based restricted stock units

was $3,115 for the 26 weeks ended July 31, 2021. Stock-based compensation benefit for performance-based restricted stock units was $100 for the 26 weeks ended August 1, 2020. At July 31, 2021, there was approximately $18,130 of unrecognized stock-based compensation expense related to performance-based restricted stock units.