Following our 2006 acquisition of Guidant, we assumed the Guidant Supplemental Retirement Plan, a frozen, non-qualified defined benefit plan for certain former officers and employees of Guidant. The Guidant Supplemental Retirement Plan was partially funded through a Rabbi Trust that contains segregated company assets within restricted cash used to pay the benefit obligations related to the plan.

We also maintain an Executive Retirement Plan, a defined benefit plan covering executive officers and other key contributors. Participants may retire with benefits once retirement conditions have been satisfied.

As a result of our 2019 acquisition of BTG plc. (BTG), we assumed a benefit obligation related to a defined benefit pension plan sponsored by BTG for eligible United Kingdom employees. During the second quarter of 2022, we transferred the benefit obligation and associated assets of the pension plan to third party insurers, and as a result, were relieved from primary responsibility of the benefit obligation and the related plan assets. The transaction did not have a material impact on our financial position or results of operations.

We use a December 31 measurement date for these plans and record the net unfunded and underfunded portion as a liability within non-current liabilities, with the current portion within accrued expenses, on the consolidated balance sheets, recognizing changes primarily through OCI. As of December 31, 2023 and 2022, the funded status of our plans were unfunded or underfunded in aggregate. The outstanding obligation is as follows:


	As of December 31, 2023
(in millions)	Accumulated Benefit Obligation (ABO)		Projected Benefit Obligation (PBO)		Fair value of Plan Assets		Unfunded/Underfunded PBO Recognized
Domestic Retirement Plans	$	54	$	59	$	—	$	59


Other International Retirement Plans	145		159		101		58
	$	199	$	218	$	101	$	117


	As of December 31, 2022
(in millions)	Accumulated Benefit Obligation (ABO)		Projected Benefit Obligation (PBO)		Fair value of Plan Assets		Unfunded/Underfunded PBO Recognized
Domestic Retirement Plans	$	50	$	55	$	—	$	55

Other International Retirement Plans	140		152		101		51
	$	190	$	207	$	101	$	105


	Year Ended December 31,
(in millions)	2023		2022
Beginning obligations	$	207	$	502

Service costs	10		13
Interest costs	7		3
Actuarial (gain) loss	(4)		(54)
Plan curtailments/settlements	(0)		(191)

Plan amendments and assumption changes	6		(25)
Benefits paid	(10)		(6)
Impact of foreign currency fluctuations	3		(37)
Ending obligation	$	218	$	207


	Weighted Average Discount Rate	Weighted Average Expected Return		Weighted Average Rate of Compensation Increase(1)

Domestic Retirement Plans	4.89%	n/a	2.00%

Other International Retirement Plans	2.85%		2.66%	3.00%

(1) Rates of compensation increase were not weighted by relative fair value. As such, the amount represents the median of the inputs and is not a weighted average.


	Weighted Average Discount Rate	Weighted Average Expected Return	Weighted Average Rate of Compensation Increase(1)
Domestic Retirement Plans	5.32%	n/a	2.00%

Other International Retirement Plans	2.62%	2.27%	3.00%

(1) Rates of compensation increase were not weighted by relative fair value. As such, the amount represents the median of the inputs and is not a weighted average.

A reconciliation of the changes in the fair value of plan assets for our funded retirement plans is as follows:


	Year Ended December 31,
(in millions)	2023		2022
Beginning fair value	$	101	$	336

Actual return on plan assets	(1)		(2)
Employer contributions	11		16
Participant contributions	1		1
Plan curtailments/settlements	(0)		(185)
Actuarial gain (loss)	(0)		(25)
Benefits paid	(10)		(9)
Impact of foreign currency fluctuations	0		(32)
Ending fair value	$	101	$	101

For our defined benefit plans, we base our discount rate on the rates of return available on high-quality bonds with maturities approximating the expected period over which benefits will be paid. The rate of compensation increase is based on historical and expected rate increases. We base our rate of expected return on plan assets on historical experience, our investment guidelines and expectations for long-term rates of return. Our assets are invested in a variety of securities, primarily equity securities and government bonds. These securities are considered Level 1 and Level 2 investments.

Expected benefit payments are estimated based on the same assumptions used in determining our benefit obligation as of December 31, 2023. Actual benefit payments will depend on future employment and compensation, average years employed and average life spans, in addition to other factors. Changes in any of these factors could significantly impact these estimated future benefit payments. Benefit payments expected to be paid during the next ten years for our Domestic Retirement Plans and our Other International Retirement Plans are as follows:

We also sponsor a voluntary 401(k) Retirement Savings Plan for eligible employees. We match 200 percent of employee elective deferrals for the first two percent of employee eligible compensation and 50 percent of employee elective deferrals greater than two percent, but not exceeding six percent, of employee eligible compensation. Total expense for our matching contributions to the plan was $135 million in 2023, $123 million in 2022 and $118 million in 2021.