We have annual short-term incentive compensation plans for senior management and certain other employees payable at our election in cash, shares of common stock, or a combination of cash and shares of common stock. Amounts earned under STI Plans are based on our Adjusted EBITDA, modified for certain safety, quality, delivery, cost, and individual performance factors. The Adjusted EBITDA targets are determined based on the return on adjusted net assets. Most of our production facilities have similar programs for both hourly and salaried employees. In addition, we have discretionary bonus programs that allow for management to incentivize employees based on performance. As of December 31, 2023, we had a liability of $11.4 million recorded within Accrued salaries, wages and related expenses for estimated probable future payments relating to the 12-month performance period of our 2023 STI Plans.

General. Executive officers and other key employees of the Company, as well as non-employee directors of the Company, are eligible to participate in the Kaiser Aluminum Corporation 2021 Equity and Incentive Compensation Plan (“2021 Plan”). The 2021 Plan was approved by stockholders on June 3, 2021 and replaced and succeeded, in its entirety, the Kaiser Aluminum Corporation Amended and Restated 2016 Equity and Performance Incentive Plan, except with regard to awards previously granted thereunder that continued to be outstanding. At December 31, 2023, 506,031 shares were available for awards under the 2021 Plan.

Non-Vested Common Shares and Restricted Stock Units. We grant non-vested common shares (“RSAs”) to our non-employee directors and restricted stock units (“RSUs”) to our executive officers and other key employees. The RSUs have rights similar to the rights of RSAs, and each RSU that becomes vested entitles the recipient to receive one common share, for which we issue new shares of our common stock upon vesting under the 2021 Plan, or a cash amount equaling the value of one common share. The service period is generally one year for RSAs granted to non-employee directors and three years for RSUs granted to executive officers and other key employees.

The following table summarizes activity relating to RSAs and RSUs for the year ended December 31, 2023:


	Shares			Weighted- Average Grant-Date Fair Value per Share
Outstanding at December 31, 2022		323,179		$	87.59
Granted		171,710			71.81
Vested		(80,452	)		90.82
Forfeited		(15,050	)		80.92
Outstanding at December 31, 2023		399,387		$	80.41

Performance Shares. We grant performance shares to executive officers and other key employees that vest upon the achievement of specified market or internal performance goals. Performance goals can include: (i) our achieving a total shareholder return (“TSR”) compared to the TSR of a specified group of peer companies over a three-year performance period (“TSR-Based Performance Shares”); (ii) achieving targeted improvements to our total controllable cost performance over a three-year performance period; and/or (iii) achieving targeted improvements to our Adjusted EBITDA margin performance, measured by our Adjusted EBITDA as a percentage of Conversion Revenue, over a three-year performance period. Each performance share that becomes vested and earned entitles the recipient to receive

one common share or a cash amount equaling the value of one common share. The number of performance shares that may be earned and result in the issuance of cash or common shares ranges between 0% to 200% of the target number of underlying performance shares.

The following table presents the weighted average inputs and assumptions used in the Monte Carlo simulations to calculate the fair value at the grant date of our TSR-Based Performance Shares:


	Year Ended December 31,
	2023			2022			2021
Grant date fair value	$	104.87		$	122.22		$	151.98
Grant date stock price	$	84.33		$	95.13		$	114.71
Expected volatility of Kaiser Aluminum1		49.72	%		49.37	%		45.71	%
Expected volatility of peer companies1		45.14	%		51.08	%		50.69	%
Risk-free interest rate		4.59	%		1.59	%		0.29	%
Dividend yield		3.65	%		3.24	%		2.51	%

Weighted average expected volatility based on 2.8 years of daily closing share prices from the valuation date to the end of the performance period.

The following table summarizes activity relating to performance shares for the year ended December 31, 2023:


	Shares			Weighted- Average Grant-Date Fair Value per Share
Outstanding at December 31, 2022		367,552		$	114.25
Granted 1		98,708			96.65
Forfeited 1		(3,932	)		119.15
Canceled 1		(133,712	)		99.79
Outstanding at December 31, 2023		328,616		$	114.79

The number of shares granted and forfeited are presented at their maximum payout; and the number of shares canceled includes the number of shares that did not vest due to performance results falling below those required for maximum payout.

Non-Cash Compensation Expense. Non-cash compensation expense is primarily included in SG&A and R&D. The following table presents non-cash compensation expense by type of award under LTI Programs (in millions of dollars):


	Year Ended December 31,
	2023		2022		2021
RSAs and RSUs	$	10.7	$	8.8	$	8.1
Performance shares		4.7		4.9		4.5
Total non-cash compensation expense	$	15.4	$	13.7	$	12.6

Recognized tax benefits relating to the non-cash compensation expense presented in the table above were $3.6 million, $3.2 million and $3.0 million for 2023, 2022, and 2021, respectively.

The aggregate fair value of awards that vested was $6.2 million, $9.1 million and $9.7 million for 2023, 2022, and 2021, respectively, which represents the market value of our common stock on the date that the awards vested.

Unrecognized Gross Compensation Cost Data. The following table presents unrecognized gross compensation costs and the expected period over which the remaining gross compensation costs will be recognized by type of award as of December 31, 2023:


	Unrecognized Gross Compensation Costs (in millions of dollars)		Expected Period (in years) Over Which the Remaining Gross Compensation Costs Will Be Recognized
RSAs and RSUs	$	14.0		2.3
Performance shares	$	6.0		1.8

The following table presents the weighted-average grant-date fair value per share for shares granted by type of award:


	Year Ended December 31,
	2023		2022		2021
RSAs and RSUs	$	71.81	$	84.16	$	107.24
Performance shares	$	96.65	$	111.37	$	137.06

Participants may elect to have us withhold common shares to satisfy minimum statutory tax withholding obligations arising in connection with the vesting of RSAs, RSUs, and performance shares. We cancel any such shares withheld on the applicable vesting dates or earlier dates when service requirements are satisfied, which correspond to the times at which income to the participant is recognized. When we withhold these common shares, we are required to remit to the appropriate taxing authorities the fair value of the shares withheld as of the vesting date. The withholding of common shares by us could be deemed a purchase of the common shares. See Statements of Consolidated Stockholders’ Equity for details on cancellation of shares to cover tax withholdings upon common shares issued.