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 for the periods indicated:

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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 56 and 41 stock options during the 13 weeks ended May 4, 2024 and April 29, 2023, respectively. Stock-based compensation expense for stock options was $1,680 and $1,470 for the 13 weeks ended May 4, 2024 and April 29, 2023, respectively. The weighted-average grant date fair value of these stock options was $157.66 and $200.67 for the 13 weeks ended May 4, 2024 and April 29, 2023, respectively. At May 4, 2024, there was approximately $16,803 of unrecognized stock-based compensation expense related to unvested stock options.

There were 44 and 38 restricted stock units issued during the 13 weeks ended May 4, 2024 and April 29, 2023, respectively. Stock-based compensation expense for restricted stock units was $4,388 and $4,359 for the 13 weeks ended May 4, 2024 and April 29, 2023, respectively. At May 4, 2024, there was approximately $43,539 of unrecognized stock-based compensation expense related to restricted stock units.

There were 71 and 32 performance-based restricted stock units issued during the 13 weeks ended May 4, 2024 and April 29, 2023. Stock-based compensation expense for performance-based restricted stock units was $4,014 and $3,892 for the 13 weeks ended May 4, 2024 and April 29, 2023, respectively. At May 4, 2024, there was approximately $34,998 of unrecognized stock-based compensation expense related to performance-based restricted stock units.