PENSION AND OTHER POSTRETIREMENT DEFINED BENEFIT PLANS We sponsor various qualified and non-qualified defined benefit pension plans for our eligible associates. We also maintain hourly and salaried benefit plans that provide postretirement medical, dental, vision and life insurance benefits (OPEB) to our eligible retirees and their dependents in the U.S.

Actuarial valuations of our benefit plans were made as of December 31, 2024 and 2023. The primary weighted-average assumptions used in the year-end valuation of our principal plans appear in the following table. The U.S. discount rates are based on an actuarial review of a hypothetical portfolio of long-term, high quality corporate bonds matched against the expected payment stream for each of our plans. The discount rates for the non-U.S. plans are based on hypothetical yield curves developed from corporate bond yield information within each regional market. The assumptions for expected return on plan assets are based on future capital market expectations for the asset classes represented within our portfolios and a review of long-term historical returns. The rates of increase in compensation and health care costs are based on current market conditions, inflationary expectations and historical information.


	Pension Benefits												OPEB
	2024				2023				2022				2024		2023		2022
	U.S.		Non-U.S.		U.S.		Non-U.S.		U.S.		Non-U.S.
Discount rate	5.65	%	4.95	%	5.15	%	4.50	%	5.50	%	4.40	%	5.70	%	5.15	%	5.50	%
Expected return on plan assets	6.75	%	5.80	%	6.75	%	4.90	%	6.75	%	4.00	%	N/A		N/A		N/A

Rate of compensation increase	N/A		3.30	%	N/A		3.30	%	N/A		3.25	%	4.00	%	4.00	%	4.00	%

The accumulated benefit obligation for all defined benefit pension plans was $459.3 million and $486.9 million at December 31, 2024 and December 31, 2023, respectively. As of December 31, 2024, the accumulated benefit obligation for our underfunded defined benefit pension plans was $383.5 million, the projected benefit obligation was $383.5 million and the fair value of assets for these plans was $298.2 million.

Certain eligible retirees under our OPEB plans have past service with both AAM and GM. AAM and GM share proportionally in the cost of OPEB for these retirees based on the length of service an employee had with AAM and GM. We have included in our OPEB obligation the amounts expected to be received from GM pursuant to this agreement of $120.4 million and $120.0 million at December 31, 2024 and December 31, 2023, respectively. We have also recorded a corresponding asset for these amounts on our Consolidated Balance Sheet, $8.7 million that is classified as a current asset and $111.7 million that is classified as a noncurrent asset as of December 31, 2024.


	Pension Benefits				OPEB
	December 31,				December 31,
	2024		2023		2024		2023
	(in millions)
Change in benefit obligation
Benefit obligation at beginning of year	$	486.9	$	482.4	$	287.8	$	329.6
Service cost	1.0		1.1		0.2		0.2
Interest cost	23.2		24.4		8.4		10.1
Plan amendments	—		(0.6)		(1.9)		—
Actuarial loss (gain)	(12.6)		6.7		(0.9)		(21.4)
Change in GM portion of OPEB obligation	—		—		0.4		(18.2)
Participant contributions	0.1		0.2		—		—

Curtailments	—		(0.5)		—		—
Settlements	—		(6.1)		—		—
Benefit payments	(35.5)		(27.5)		(8.7)		(12.5)

Currency fluctuations	(3.8)		6.8		—		—

Net change	(27.6)		4.5		(2.5)		(41.8)
Benefit obligation at end of year	$	459.3	$	486.9	$	285.3	$	287.8

Change in plan assets
Fair value of plan assets at beginning of year	$	408.1	$	406.9	$	—	$	—
Actual return on plan assets	1.9		19.0		—		—
Employer contributions	4.5		9.2		8.7		12.5
Participant contributions	0.1		0.2		—		—
Benefit payments	(35.5)		(27.5)		(8.7)		(12.5)
Settlements	—		(6.1)		—		—

Currency fluctuations	(2.6)		6.4		—		—
Net change	(31.6)		1.2		—		—
Fair value of plan assets at end of year	$	376.5	$	408.1	$	—	$	—


	Pension Benefits				OPEB
	December 31,				December 31,
	2024		2023		2024		2023
	(in millions)
Noncurrent assets	$	2.5	$	1.7	$	—	$	—
Current liabilities	(7.0)		(5.8)		(20.0)		(18.9)
Noncurrent liabilities	(78.3)		(74.7)		(265.3)		(268.9)
Net liability	$	(82.8)	$	(78.8)	$	(285.3)	$	(287.8)

The increase in net actuarial loss for pension benefits was primarily attributable to the impact of the actual return on pension assets in 2024 as compared to our assumption for expected return on pension assets, partially offset by increased discount rates used in the valuation at December 31, 2024, as compared to prior year, and the impact of amortization of prior actuarial losses. The decrease in net actuarial gain for OPEB benefits was primarily attributable to amortization of prior actuarial gains.


	Pension Benefits						OPEB
	December 31,						December 31,
	2024		2023		2022		2024		2023		2022
	(in millions)
Service cost	$	1.0	$	1.1	$	1.7	$	0.2	$	0.2	$	0.3
Interest cost	23.2		24.4		16.5		8.4		10.1		8.4
Expected asset return	(28.7)		(29.3)		(31.0)		—		—		—
Amortized actuarial loss (gain)	6.9		4.1		7.6		(10.0)		(8.5)		0.5
Amortized prior service cost (credit)	—		0.1		0.1		(0.5)		(0.5)		(0.9)


Curtailment charge	—		1.2		—		—		—		—
Settlement charge	—		0.1		—		—		—		—
Net periodic benefit cost (credit)	$	2.4	$	1.7	$	(5.1)	$	(1.9)	$	1.3	$	8.3

Our postretirement cost sharing asset from GM is measured on the same basis as the portion of the obligation to which it relates. The actuarial gains and losses related to the GM portion of the OPEB obligation are recognized immediately in the Consolidated Statements of Operations as an offset against the gains and losses related to the change in the corresponding GM postretirement cost sharing asset. These items are presented net in the change in benefit obligation and net periodic benefit cost components disclosed above. Remaining actuarial gains and losses are deferred and amortized over the expected future service periods of the active participants or the remaining life expectancy of the inactive participants.

The expected future pension and other postretirement benefits to be paid, net of GM cost sharing, for each of the next five years and in the aggregate for the succeeding five years thereafter are as follows: $54.1 million in 2025; $55.0 million in 2026; $51.2 million in 2027; $51.2 million in 2028; $54.2 million in 2029 and $235.6 million for 2030 through 2034. These amounts were estimated using the same assumptions that were used to measure our 2024 year-end pension and OPEB obligations and include an estimate of future employee service.

Contributions We contributed $1.7 million to our pension trusts in 2024. Due to the availability of our pre-funded pension balances (previous contributions in excess of prior required pension contributions), we expect our regulatory pension funding requirements in 2025 to be approximately $1.1 million. We expect our cash payments, net of GM cost sharing, for OPEB to be approximately $11.6 million in 2025.

Pension plan assets The weighted-average asset allocations of our pension plan assets at December 31, 2024 and 2023 appear in the following table. The asset allocation for our plans is developed in consideration of the demographics of the plan participants and expected payment stream of the benefit obligation.


	U.S.					Non-U.S.
					Target					Target
	2024		2023		Allocation	2024		2023		Allocation
Equity securities	25.8	%	23.8	%	25% - 35%	15.1	%	17.8	%	15% - 25%
Fixed income securities	67.3		69.3		60% - 70%	62.2		61.7		60% - 70%
Alternative assets	5.7		5.6		0% - 10%	18.1		15.4		5% - 15%
Cash	1.2		1.3		0% - 5%	4.6		5.1		0% - 5%
Total	100.0	%	100.0	%		100.0	%	100.0	%

The primary objective of our pension plan assets is to provide a source of retirement income for participants and beneficiaries. Our primary financial objectives for the pension plan assets have been established in conjunction with a comprehensive review of our current and projected financial requirements. These objectives include having the ability to pay all future benefits and expenses when due, maintaining flexibility and minimizing volatility. These objectives are based on a long-term investment horizon.

Defined Benefit Pension Plan Assets Investments in our defined benefit plans are stated at fair value. Level 1 assets are valued using quoted market prices that represent the asset value of the shares held by the trusts. The level 2 assets are investments in pooled funds, which are valued using a model to reflect the valuation of their underlying assets that are publicly traded with observable values. The fair values of our pension plan assets are as follows:


December 31, 2024
Asset Categories	Level 1		Level 2		Level 3		Total
	(in millions)
Cash and Cash Equivalents	$	7.4	$	0.6	$	—	$	8.0
Equity
U.S. Large Cap	28.8		1.3		—		30.1
U.S. Small/Mid Cap	22.4		—		—		22.4
World Equity	32.7		0.7		—		33.4
Fixed Income Securities
Government & Agencies	48.2		30.6		—		78.8
Corporate Bonds - Investment Grade	146.7		0.4		—		147.1
Corporate Bonds - Non-investment Grade	9.5		0.1		—		9.6
Emerging Market Debt	7.8		0.2		—		8.0
Other	1.8		2.7		—		4.5
Other
Property Funds (a)	—		—		—		20.9
Other (a)	—		—		—		13.7
Total Plan Assets	$	305.3	$	36.6	$	—	$	376.5

December 31, 2023
Asset Categories	Level 1		Level 2		Level 3		Total
	(in millions)
Cash and Cash Equivalents	$	8.5	$	1.3	$	—	$	9.8
Equity
U.S. Large Cap	37.2		2.2		—		39.4
U.S. Small/Mid Cap	11.5		—		—		11.5
World Equity	36.2		3.0		—		39.2
Fixed Income Securities
Government & Agencies	60.3		37.6		—		97.9
Corporate Bonds - Investment Grade	150.2		0.9		—		151.1
Corporate Bonds - Non-investment Grade	10.3		0.4		—		10.7
Emerging Market Debt	10.6		—		—		10.6
Other	2.5		1.0		—		3.5
Other
Property Funds (a)	—		—		—		22.6
Other (a)	—		—		—		11.8
Total Plan Assets	$	327.3	$	46.4	$	—	$	408.1

(a) In accordance with ASC 820 - Fair Value Measurement certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets.

DEFINED CONTRIBUTION PLANS Most of our salaried and hourly U.S. associates, including certain UAW represented associates at our U.S. locations, are eligible to participate in voluntary savings plans. Our maximum match is 50% of eligible associates' contribution up to 10% of their eligible salary. Matching contributions amounted to $9.6 million in 2024, $9.4 million in 2023 and $8.6 million in 2022. Certain U.S. associates are eligible annually to receive an additional AAM Retirement Contribution (ARC) benefit between 3% to 5% of eligible salary, depending on years of service. We made ARC contributions of $10.3 million, $9.9 million and $9.0 million in 2024, 2023 and 2022, respectively.