During the three months ended March 31, 2022 and 2021, we granted performance share units (which we refer to as “PSUs”) covering up to 0.5 million and 0.2 million shares of common stock, respectively, assuming maximum level of performance, with a grant date fair value of $55.93 and $58.28 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 three months ended March 31, 2022 and 2021, 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 0.9 million shares will vest in 2022 to 2024 if the defined maximum performance targets are met, and no shares will vest if the defined minimum performance targets are not met. During the three months ended March 31, 2022 and 2021, 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 $64.37 and $52.74 per share, respectively, that primarily vest over a three year period.

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 March 31, 2022
Unvested units		1,026
Unrecognized compensation cost	$	34,672
Weighted-average period to recognize compensation cost		1.97

During the three months ended March 31, 2022 and 2021, we recognized stock-based compensation expense of $4.1 million and $3.0 million, respectively. Stock-based compensation expense is included in selling, general, and administrative expense on our condensed consolidated statements of operations.