Employee Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2023

Summary of RSAs and RSUs Activity

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

Summary of Performance Shares Activity

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

1.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.

Summary of Non-Cash Compensation Expense under LTI Programs

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

Summary of Unrecognized Gross Compensation Cost and Expected Period Over Which Remaining Gross Compensation Costs Will Be Recognized By Type of Award

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

Summary of Weighted-Average Grant-Date Fair Value per Share for Shares Granted by Type of Award

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

Performance Shares

Summary of Weighted Average Inputs and Assumptions Used to Calculate Fair Value at Grant Date

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	%

1.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.