At March 31, 2024 and December 31, 2023, 9,170,507 and 10,211,459 shares of common stock, respectively, were available for grant under our Incentive Plan. The unamortized compensation cost of awards issued under the Incentive Plan, which are settled by delivery of shares of common stock, and purchases under the Employee Stock Purchase Plan, totaled $41 million at March 31, 2024, as shown in the following table.


	Three Months Ended March 31, 2024
(In Thousands)	Restricted Stock Units		Deferred Stock Units		Performance Stock Units		Employee Stock Purchase Plan		Total
Unrecognized compensation cost at beginning of period	$	3,166	$	18,920	$	15,519	$	—	$	37,605
Equity grants	3,522		6,915		—		266		10,703
Performance-based valuation adjustment	—		—		—		—		—
Equity grant forfeitures (1)	(401)		(1,114)		—		—		(1,515)
Equity compensation expense	(711)		(3,172)		(1,785)		(67)		(5,735)
Unrecognized Compensation Cost at End of Period	$	5,576	$	21,549	$	13,734	$	199	$	41,058

(1)Equity grant forfeitures for the three months ended March 31, 2024 represent the reduction in future equity compensation expense related to employee terminations, for which the underlying equity awards will be forfeited upon the actual employee termination date subsequent to March 31, 2024.

At March 31, 2024, the weighted average amortization period remaining for all of our equity awards was less than two years.

We generally grant RSUs annually, as part of our compensation process. In addition, RSUs are granted from time to time in connection with hiring and promotions. RSUs generally vest over the course of a four-year vesting period, and are distributed annually, at the end of each vesting period.

At March 31, 2024 and December 31, 2023, we had 865,279 and 593,570 RSUs outstanding, respectively. During the three months ended March 31, 2024, we granted 542,719 RSUs and distributed 271,010 RSUs. Unvested RSUs at March 31, 2024 vest through 2028.

We generally grant DSUs annually, as part of our compensation process. In addition, DSUs are granted from time to time in connection with hiring and promotions and in lieu of the payment in cash of a portion of annual bonus earned. DSUs generally vest over the course of a four-year vesting period, and are distributed after the end of the final vesting period or after an employee is terminated.

At March 31, 2024 and December 31, 2023, we had 5,598,779 and 4,821,172 DSUs outstanding, respectively, of which 2,309,485 and 2,284,480, respectively, had vested. During the three months ended March 31, 2024, we granted 1,089,871 DSUs and distributed 312,264 DSUs. Unvested DSUs at March 31, 2024 vest through 2028.

We generally grant PSUs annually, as part of our compensation process. PSUs generally have performance-based vesting over the course of a three-year vesting/performance period, and, subject to meeting certain performance criteria, will vest and be distributed after the end of the vesting period.

At March 31, 2024 and December 31, 2023, the target number of PSUs that were unvested was 2,598,194 and 3,072,039, respectively. Vesting for PSUs generally occurs approximately three years from their respective grant dates based on various total shareholder return performance calculations, as discussed in Note 19 to the Consolidated Financial Statements included in our Annual Report on Form 10-K for the year ended December 31, 2023.

For 473,845 target PSU awards that were granted in December 2020, the performance vesting period ended on January 1, 2024. Based upon the performance-based vesting criteria of these awards, 564,975 shares of our common stock underlying these PSUs

qualified for vesting, which was approved by our Board of Directors during the three months ended March 31, 2024. These PSUs were distributed as shares of our common stock in April 2024.

The ESPP allows a maximum of 850,000 shares of common stock to be purchased in aggregate for all employees. As of March 31, 2024 and December 31, 2023, 785,530 and 763,369 shares had been purchased, respectively, and there remained a negligible amount of uninvested employee contributions in the ESPP at March 31, 2024.