9.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:

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The expected volatility is based on the historical volatility of the Company’s common stock. The risk-free interest rate is based on the United States Treasury yield curve in effect on the date of grant for the respective expected life of the option. The expected life represents the time the options granted are expected to be outstanding. The expected life of options granted is derived from historical data on Ulta Beauty stock option exercises. Forfeitures of stock options are estimated at the grant date based on historical rates of stock option activity and reduce the stock-based compensation expense recognized. The Company does not currently pay a regular dividend.

The Company granted 48 and 61 stock options during the 13 weeks ended April 30, 2022 and May 1, 2021, respectively. Stock-based compensation expense for stock options was $2,342 and $2,897 for the 13 weeks ended April 30, 2022 and May 1, 2021, respectively. The weighted-average grant date fair value of these stock options was $149.14 and $109.72 for the 13 weeks ended April 30, 2022 and May 1, 2021, respectively. At April 30, 2022, there was approximately $16,062 of unrecognized stock-based compensation expense related to unvested stock options.

There were 50 and 52 restricted stock units issued during the 13 weeks ended April 30, 2022 and May 1, 2021, respectively. Stock-based compensation expense for restricted stock units was $4,452 and $4,835 for the 13 weeks ended April 30, 2022 and May 1, 2021, respectively. At April 30, 2022, there was approximately $35,627 of unrecognized stock-based compensation expense related to restricted stock units.

There were 37 and 46 performance-based restricted stock units issued during the 13 weeks ended April 30, 2022 and May 1, 2021. Stock-based compensation expense for performance-based restricted stock units was $3,562 and $1,246 for the 13 weeks ended April 30, 2022 and May 1, 2021, respectively. At April 30, 2022, there was approximately $25,921 of unrecognized stock-based compensation expense related to performance-based restricted stock units.