Stock-based compensation expense charged to income for the plans was $69.5 million and $58.8 million for the first three quarters of 2023 and 2022, respectively. Total unrecognized compensation cost for all stock-based compensation plans was $156.9 million as of October 29, 2023, which is expected to be recognized over a weighted-average period of 2.2 years.


	Stock Options			Performance-Based Restricted Stock Units			Restricted Shares			Restricted Stock Units
	Number	Weighted-Average Exercise Price		Number	Weighted-Average Grant Date Fair Value		Number	Weighted-Average Grant Date Fair Value		Number	Weighted-Average Grant Date Fair Value
	(In thousands, except per share amounts)
Balance as of January 29, 2023	866	$	230.78	166	$	295.93	5	$	308.66	221	$	323.89
Granted	212	358.97		121	296.14		4	368.36		127	359.69
Exercised/released	166	150.49		104	201.56		5	308.66		99	291.10
Forfeited/expired	28	332.37		8	350.89		1	368.36		19	348.82
Balance as of October 29, 2023	884	$	273.39	175	$	349.78	3	$	368.36	230	$	355.73
Exercisable as of October 29, 2023	423	$	203.17

The Company's performance-based restricted stock units are awarded to eligible employees and entitle the grantee to receive a maximum of two shares of common stock per performance-based restricted stock unit if the Company achieves specified performance goals and the grantee remains employed during the vesting period. The fair value of performance-based restricted stock units is based on the closing price of the Company's common stock on the grant date. Expense for performance-based restricted stock units is recognized when it is probable that the performance goal will be achieved.

The grant date fair value of each stock option granted is estimated on the date of grant using the Black-Scholes model. The closing price of the Company's common stock on the grant date is used in the model. The assumptions used to calculate the fair value of the options granted are evaluated and revised, as necessary, to reflect market conditions and the Company's historical experience. The expected term of the options is based upon the historical experience of similar awards, giving consideration to expectations of future employee exercise behavior. Expected volatility is based upon the historical volatility of the Company's common stock for the period corresponding with the expected term of the options. The risk-free interest rate is based on the U.S. Treasury yield curve for the period corresponding with the expected term of the options. The following are weighted averages of the assumptions that were used in calculating the fair value of stock options granted during the first three quarters of 2023:

The Company's board of directors and stockholders approved the Company's Employee Share Purchase Plan ("ESPP") in September 2007. Contributions are made by eligible employees, subject to certain limits defined in the ESPP, and the Company matches one-third of the contribution. The maximum number of shares authorized to be purchased under the ESPP is 6.0 million shares. All shares purchased under the ESPP are purchased in the open market. During the third quarter of 2023, there were 25.7 thousand shares purchased.

The Company offers defined contribution pension plans to its eligible employees. Participating employees may elect to defer and contribute a portion of their eligible compensation to a plan up to limits stated in the plan documents, not to exceed the dollar amounts set by applicable laws. The Company matches 50% to 75% of the contribution depending on the participant's length of service, and the contribution is subject to a two year vesting period. The Company's net expense for the defined contribution plans was $14.6 million and $10.1 million in the first three quarters of 2023 and 2022, respectively.