During the six months ended June 30, 2023 and 2022, we granted restricted stock units (which we refer to as “RSUs”) covering 0.2 million and 0.2 million shares of common stock, respectively, with a grant date fair value of $62.61 and $63.77 per share, respectively, that primarily vest over a three year period. During the six months ended June 30, 2023 and 2022, we granted 11.0 thousand and 11.0 thousand shares of common stock, respectively, on an unrestricted basis (which we refer to as “stock awards”) with a grant date fair value of $65.77 and $54.46 per share, respectively, to our non-employee directors.

During the six months ended June 30, 2023 and 2022, we granted performance share units (which we refer to as “PSUs”) covering up to 0.5 million and 0.5 million shares of common stock, respectively, assuming maximum level of performance, with a grant date fair value of $60.05 and $55.93 per share, respectively, that are subject to both service and performance vesting conditions. The quantity of shares that will ultimately vest for the PSUs ranges from 0% to up to 250% of a targeted number of shares for each participant and will be determined based on an achievement of a three year adjusted pre-tax income performance goal. During the six months ended June 30, 2023 and 2022, we issued 0.3 million and 0.3 million shares of common stock, respectively, upon the vesting and settlement of PSUs that were granted in previous periods. Approximately 1.1 million shares will vest from 2024 to 2026 if the defined maximum performance targets are met, and no shares will vest if the defined minimum performance targets are not met.

A summary of our outstanding PSUs, assuming the current estimated level of performance achievement, and RSUs are as follows (in thousands, except years):


	As of June 30, 2023
Unvested units		1,014
Unrecognized compensation cost	$	32,703
Weighted-average years to recognize compensation cost		2.04

During the three months ended June 30, 2023 and 2022, we recognized stock-based compensation expense of $8.9 million and $5.7 million, respectively. During the six months ended June 30, 2023 and 2022, we recognized stock-based compensation expense of $14.3 million and $9.8 million, respectively. Stock-based compensation expense is included in selling, general, and administrative expense on our condensed consolidated statements of operations.

During the three months ended June 30, 2023, in accordance with ASC 718, Compensation—Stock Compensation we updated our recognition of stock-based compensation expense associated with previously granted PSU awards to reflect probable financial results as they relate to the performance goals of the awards. Accordingly, our estimate of the number of shares which will ultimately vest under our PSU awards increased by 90.0 thousand, and we recorded a cumulative catch-up adjustment to increase stock-based compensation expense of $3.4 million ($2.5 million net of tax), or $0.08 per share (basic and diluted), for the three and six months ended June 30, 2023.