UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

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FORM 11-K

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☒ ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2023

☐ TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from ______ to _____

Commission File Number 0-20355

A. Full title of the plan and the address of the plan, if different from that of the issuer named below:

Costco 401(k) Retirement Plan

B. Name of issuer of the securities held pursuant to the plan and the address of its principal executive office:

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Costco Wholesale Corporation

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999 Lake Drive

Issaquah, Washington 98027

COSTCO 401(k) RETIREMENT PLAN

Table of Contents

	Page
Report of Independent Registered Public Accounting Firm	1
Financial Statements:
Statements of Net Assets Available for Benefits as of December 31, 2023 and 2022	2
Statement of Changes in Net Assets Available for Benefits for the Year Ended December 31, 2023	3
Notes to Financial Statements	4
Supplementary Information:
Schedule H, Line 4i - Schedule of Assets (Held at End of Year) as of December 31, 2023	10
Signatures	24
Exhibits:
23.1 - Consent of Independent Registered Public Accounting Firm

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

Plan Participants and Plan Administrator of

Costco 401(k) Retirement Plan

Issaquah, Washington

Opinion on the Financial Statements

We have audited the accompanying statements of net assets available for benefits of Costco 401(k) Retirement Plan (the "Plan") as of December 31, 2023 and 2022, the related statement of changes in net assets available for benefits for the year ended December 31, 2023, and the related notes (collectively referred to as the "financial statements"). In our opinion, the financial statements present fairly, in all material respects, the net assets available for benefits of the Plan as of December 31, 2023 and 2022, and the changes in net assets available for benefits for the year ended December 31, 2023, in conformity with accounting principles generally accepted in the United States of America.

Basis for Opinion

These financial statements are the responsibility of the Plan's management. Our responsibility is to express an opinion on the Plan's financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) ("PCAOB") and are required to be independent with respect to the Plan in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Plan is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits, we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Plan’s internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Supplemental Information

The supplemental Schedule H, Line 4i - Schedule of Assets (Held at End of Year) as of December 31, 2023, has been subjected to audit procedures performed in conjunction with the audit of Costco 401(k) Retirement Plan’s financial statements. The supplemental schedule is the responsibility of the Plan’s management. Our audit procedures included determining whether the information presented in the supplemental schedule reconciles to the financial statements or the underlying accounting and other records, as applicable, and performing procedures to test the completeness and accuracy of the information presented in the supplemental schedule. In forming our opinion on the supplemental schedule, we evaluated whether the supplemental schedule, including its form and content, is presented in conformity with the Department of Labor’s Rules and Regulations for Reporting and Disclosure under the Employee Retirement Income Security Act of 1974. In our opinion, the supplemental schedule is fairly stated in all material respects in relation to the financial statements as a whole.

/s/ Crowe LLP

We have served as the Plan's auditor since 2023.

Oak Brook, Illinois

June 20,2024

1

COSTCO 401(k) RETIREMENT PLAN

Statements of Net Assets Available for Benefits

December 31, 2023 and 2022

(in thousands)

				2023		2022
Assets:
	Investments at fair value			$	30,435,735	$	23,048,193
	Investments at contract value:
		Fully benefit-responsive investment contracts		1,780,521		1,849,278
			Total investments	32,216,256		24,897,471
	Receivables:
		Notes receivable from participants		559,994		514,605
		Employee contributions		43,139		—
		Employer contributions		563,469		499,820
			Total receivables	1,166,602		1,014,425
	Non-interest bearing cash			1,988		1,066
Net assets available for benefits				$	33,384,846	$	25,912,962

See accompanying notes to financial statements.

2

COSTCO 401(k) RETIREMENT PLAN

Statement of Changes in Net Assets Available for Benefits

Year Ended December 31, 2023

(in thousands)

			2023
Net investment income:
	Net appreciation of investments		$	7,325,457
	Interest		51,483
	Dividends		166,802
		Total net investment income	7,543,742
Interest on notes receivable from participants			31,413
Contributions to the Plan:
	Employee		1,043,954
	Employer		644,916
		Total contributions	1,688,870
Distributions to participants and other			(1,792,141)
		Increase in net assets	7,471,884
Net assets available for benefits, beginning of year			25,912,962
Net assets available for benefits, end of year			$	33,384,846

See accompanying notes to financial statements.

3

COSTCO 401(k) RETIREMENT PLAN

Notes to Financial Statements

December 31, 2023 and 2022

(1)Plan Description

The following description of the Costco 401(k) Retirement Plan (the Plan) provides only general information. Participants should refer to the Plan document for a more complete description of the Plan. To participate in the Plan, an individual must be at least 18 years of age and an employee of Costco Wholesale Corporation (the Company or Costco) or certain subsidiaries.

The Plan is a defined contribution plan for the benefit of eligible employees, established by the Company under Section 401(a) of the Internal Revenue Code (IRC). It includes a qualified cash or deferred arrangement as described in Section 401(k). The Plan is also subject to the provisions of the Employee Retirement Income Security Act of 1974 (ERISA), as amended.

(a)Employee Contributions

The Plan allows certain employees to make compensation deferral contributions after completing 90 days of service within 12-consecutive months. Eligible employees may contribute from 1% to 50% of their compensation, subject to certain limitations set by the IRC and the Plan. Eligible employees may also contribute amounts representing certain distributions from other retirement plans (rollover contributions).

All newly-eligible participants entering the Plan are automatically enrolled at a salary contribution rate of 4%. On an active participant’s employment anniversary date and each anniversary date thereafter the percentage deferred into the Plan automatically increases by one percentage point, to a maximum of 20%. Employees may opt out of automatic enrollment and increases. Contributions are subject to regulatory requirements.

(b)Employer Contributions

Company contributions are invested in accordance with selections made by participants. If no selection has been made, the contribution defaults to the Retirement Trust Fund corresponding to the participant's age. Employer contributions are allocated based on an employee’s classification as either: covered by the collective bargaining agreements with the International Brotherhood of Teamsters; or other eligible employment.

(1)Covered by theTeamsters Agreements

Eligible employees who have completed one year of service (12 consecutive months) are eligible for an annual employer contribution beginning on the next Plan entry date. Plan entry dates for the employer contribution are January 1 and July 1. The annual employer contribution is allocated only to the accounts of eligible Plan participants who are employed on the last day of the applicable Plan year. The allocation rate varies, based on years of service, ranging from $0.05 to $0.47 per straight-time hour worked during the Plan year, up to a maximum of 2,080 hours. This annual contribution was $6.4 million for the year ended December 31, 2023, and was deposited into the Plan and allocated to participant accounts in March 2024.

(2)Other eligible employment

The Company matches the lesser of 50% of each employee’s contribution or $500 per year. In addition, eligible employees who have completed one year of service (12 consecutive months) are eligible for an annual discretionary employer contribution beginning on the next Plan entry date. Plan entry dates for the discretionary contribution are January 1 and July 1. The discretionary contribution is allocated only to the accounts of eligible Plan participants who are employed on the last day of the applicable Plan year. The allocation rate varies, based on years of service, ranging from 4% to 9% of the participant's compensation. This discretionary

4

COSTCO 401(k) RETIREMENT PLAN

Notes to Financial Statements (Continued)

December 31, 2023 and 2022

contribution was $556.8 million for the year ended December 31, 2023, and was deposited into the Plan and allocated to participant accounts in March 2024.

(c)Participants’ Accounts

Each participant’s account is credited or debited with the participant’s contributions, the Company’s contributions, earnings and losses, fees, expenses, and changes in underlying account assets. The benefit to which a participant is entitled is the vested account balance.

(d)Vesting

Participants are immediately vested in their deferral contributions and in certain other contributions as defined in the Plan document, adjusted for investment experience, fees and expenses. Vesting in any form of employer contribution is based on the following schedule:

Years of service	Percentage vested
Under 2 years	0%
2 years	20%
3 years	40%
4 years	60%
5 years or more	100%

(e)Forfeitures

If a participant terminates employment, the non-vested portion of the account balance is forfeited. The Plan document provides that forfeited amounts may at the Company's election be used to reduce future employer contributions or to pay administrative expenses. Forfeitures were immaterial during 2023. Unallocated forfeitures were immaterial as of December 31, 2023 and 2022, after consideration of forfeitures used to reduce the employer contributions funded subsequent to each year. Forfeitures are restored to a participant’s account if within five years the participant is re-hired and repays the vested account balance distributed upon termination.

(f)Investment Options

Participants may direct funds in their account to the Plan's available options. Participants may transfer amounts between investment options daily, subject to certain trading restrictions. Before 2016, participants could invest 100% of their account in Costco stock; starting January 2016, the Plan has a 50% limit on investment in Costco stock, applied prospectively.

Amounts may be temporarily invested in a cash account prior to investment in the Plan’s investment accounts. See Notes 2, 3 and 4 for additional information regarding the Plan's investments.

(g)Distributions

Upon termination of employment, total disability, reaching age 59-1/2 or death, a participant (or participant's beneficiary in the case of death) can request a full, partial or, in certain circumstances, installment or rollover distribution for the vested portion of the account. Participants are also eligible to withdraw a portion of the salary-deferral contribution account in the event of certain financial hardships.

Dividends on the Company's stock are reinvested in the participant’s Company stock account unless a distribution is requested by the participant. These dividends are reported on a gross basis, with total dividends reported as "Dividends" and the amounts distributed reported as "Distributions to participants and other" in the statement of changes in net assets available for benefits.

5

COSTCO 401(k) RETIREMENT PLAN

Notes to Financial Statements (Continued)

December 31, 2023 and 2022

(h)Notes Receivable from Participants

A participant may borrow between $1,000 up to the lesser of $50,000 or 45% of their vested account balance, reduced by the highest outstanding balance in the previous 12 months minus the outstanding balance of all loans on the date on which the loan is made, provided this amount is available in the participant's pre-tax and rollover accounts. Loans are repaid through payroll deductions over a period ranging up to four years or, if for the purchase of a principal residence, up to 15 years. The bi-weekly re-payment amount cannot exceed 25% of the participant's net pay. The interest rate is determined by the Plan Administrator from time-to-time and is comparable to rates charged by commercial lenders. At December 31, 2023, interest rates on loans outstanding ranged from 4.25% to 10.50%, with various maturities through December 2038. Participant accounts with loans are charged an application fee at initiation and an annual maintenance fee.

(i)Trustee, Recordkeeper, and Plan Administrator

Effective October 1, 2023, the Company elected to change the trustee of the Plan from T. Rowe Price Trust Company to Northern Trust Company. T. Rowe Price Retirement Services Inc. was retained as the recordkeeper for the Plan. The Costco Benefits Committee is the Plan Administrator.

(j)Administrative and Investment Expenses

Certain administrative expenses, including investment management and transaction fees, are paid by the Plan, subject to subparagraph (e) above. All other administrative expenses are paid by the Company.

(2)Summary of Significant Accounting Policies

(a)Basis of Accounting

The financial statements of the Plan are prepared under the accrual method of accounting. As required under U.S. generally accepted accounting principles (U.S. GAAP), fully benefit-responsive investment contracts (FBRIC) are reported at contract value (see Note 3), while all other investments in the Plan are reported at fair value (see Note 4). A FBRIC is a contract with a financial institution or an insurance company that provides for a stated return on principal invested over a specified period and permits withdrawals at contract value for benefit payments, loans, or transfers to other investment options offered to the participant by the Plan. Contract value is the amount participants would receive if they were to initiate permitted transactions under the terms of the Plan.

(b)Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of income and expenses during the reporting period. Actual results could differ from those estimates and assumptions.

(c)Investment Valuation and Income Recognition

The Plan invests in the Company’s common stock, common commingled trust funds and other exchange-traded equity securities held in separately managed accounts, as well as registered investment companies and the FBRIC.

Investments, other than the FBRIC, are reported at fair value. If available, quoted market prices are used to value investments. The FBRIC consists of the Capital Preservation Portfolio (CPP), which is invested in synthetic guaranteed investment contracts and is recorded at contract value. Contract value

6

COSTCO 401(k) RETIREMENT PLAN

Notes to Financial Statements (Continued)

December 31, 2023 and 2022

represents contributions made under each contract, plus earnings, less participant withdrawals and administrative expenses.

There are no reserves against contract value for credit risk of the contract issuer or otherwise. The crediting interest rate is based on a formula agreed upon with the issuer, but not less than zero. Such interest rates are reviewed on a quarterly basis for resetting. Certain events may limit the ability of the Plan to transact at contract value with the issuer. Events may include, but are not limited to, Plan termination, bankruptcy of the Company, or defunction of the trustee. In addition, certain events allow the issuer to terminate the contract and settle at an amount different from contract value. Examples of such events include: (1) an uncured violation of the Plan’s investment guidelines, (2) a breach of material obligation under the contract, (3) a material misrepresentation, or (4) a material amendment to the agreements without the consent of the issuer. The Plan Administrator believes at this time that any events that would limit the Plan’s ability to transact at contract value with participants or that allow the issuer to terminate the contract with the Plan are not probable.

Purchases and sales of securities are recorded on a trade-date basis. Interest income is recorded on an accrual basis. Dividends are recorded on the ex-dividend date. Net appreciation or depreciation of investments includes the change in the fair value of assets from one period to the next, plus realized gains and losses.

Investment securities are exposed to various risks, such as interest rate, credit, and overall market volatility. Changes in the values of investment securities could occur, and those changes could materially affect the amounts reported in the statements of net assets available for benefits and participant account balances.

(d)Notes Receivable from Participants

Participant loans are classified as notes receivable from participants, which are segregated from Plan investments and measured at their unpaid principal balance plus any accrued but unpaid interest. Delinquent notes receivable are reclassified as distributions based upon the terms of the Plan document.

(e)Distribution of Benefits

Distributions of benefits are recorded when paid.

(f)     Subsequent Events

The Plan monitors significant events occurring after the statement of net assets available for benefits date and prior to the issuance of the financial statements to determine the impacts, if any, on the financial statements to be issued. The Plan has evaluated subsequent events through the date which the financial statements are issued.

(3)Fully Benefit-Responsive Investment Contract

The CPP is invested in synthetic guaranteed investment contracts, which consist of a portfolio of underlying assets owned by the Plan and wrap contracts issued by an insurance company and a financial institution. The issuers of the wrap contracts provide for unscheduled withdrawals from the contracts at contract value, regardless of the value of the underlying assets, in order to fund routine withdrawals.

(4)Fair Value Measurement

U.S. GAAP defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Fair value is estimated by

7

COSTCO 401(k) RETIREMENT PLAN

Notes to Financial Statements (Continued)

December 31, 2023 and 2022

applying a fair value hierarchy, which requires maximizing the use of observable inputs. The three levels of inputs are:

Level 1: Quoted market prices in active markets for identical assets or liabilities.

Level 2: Observable market-based inputs or unobservable inputs that are corroborated by market data.

Level 3: Significant unobservable inputs that are not corroborated by market data.

The asset or liability's fair value measurement level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Valuation techniques maximize the use of relevant observable inputs and minimize the use of unobservable inputs. Valuation techniques utilized during the reporting period were not changed from previous practice. The following is a description of the valuation methodologies used for assets measured at fair value.

Common stock, underlying securities in separately managed accounts, and registered investment company funds: These investments are deemed to be actively traded and are valued at the closing price reported in the active market in which the individual securities are traded. These assets are valued using Level 1 inputs. Mutual funds held by the Plan are open-end mutual funds that are registered with the U.S. Securities and Exchange Commission. Separately managed accounts largely consist of common stock and a collective trust as of December 31, 2023, and 2022.

Common commingled trust funds: The valuation techniques used to measure the fair value of common commingled trust funds are based on quoted market prices, such as quoted net asset values (NAV) published by the fund as supported in an active market. Plan participant transactions of investment or withdrawals may occur on a daily basis in these trusts. These assets are valued using Level 1 inputs.

The tables below present information regarding investments that are measured at fair value on a recurring basis and indicate the level within the hierarchy reflecting the valuation techniques utilized to determine fair value as of December 31, 2023, and 2022.

December 31, 2023:	Level 1 (in 000's)
Investments, at fair value:
Costco Wholesale Corporation common stock	$	15,977,459
Common commingled trust funds	10,080,126
Separately managed accounts	2,491,563
Registered investment company funds	1,886,587
Total investments in fair value hierarchy	$	30,435,735

December 31, 2022:	Level 1 (in 000's)
Investments, at fair value:
Costco Wholesale Corporation common stock	$	11,486,680
Common commingled trust funds	7,865,744
Separately managed accounts	2,171,053
Registered investment company funds	1,524,716
Total investments in fair value hierarchy	$	23,048,193

8

COSTCO 401(k) RETIREMENT PLAN

Notes to Financial Statements (Continued)

December 31, 2023 and 2022

(5)Plan Termination

Although it has no present intent to do so, the Company has the right under the Plan to discontinue its contributions at any time and to terminate the Plan, subject to ERISA and the requirements of the collective bargaining agreements with the Teamsters. In the event of termination, participants will become 100% vested in their accounts.

(6)Tax Status

In a determination letter dated June 9, 2017, the Internal Revenue Service informed the Company that the Plan is designed in accordance with applicable sections of the IRC. The Plan has since been restated and amended. The Plan Administrator believes that the Plan is designed and is being operated in compliance with the IRC.

U.S. GAAP requires the Plan Administrator to evaluate tax positions taken by the Plan and recognize a tax liability (or asset) if the Plan has taken an uncertain position that more likely than not would not be sustained upon examination by the IRS. The Plan Administrator has concluded that as of December 31, 2023, there are no uncertain positions taken or expected to be taken that would require recognition of a liability (or asset) or disclosure in the financial statements. The Plan is subject to routine audits by taxing jurisdictions; there are currently no audits in progress.

(7)Party-in-Interest and Related Party Transactions

Certain Plan investments are shares of registered investment companies, fully benefit-responsive investment contracts, and common commingled trust funds managed by Northern Trust Company and T. Rowe Price Trust Company. Northern Trust Company and T. Rowe Price Retirement Services Inc. are the trustee and recordkeeper as defined by the Plan, therefore these transactions qualify as exempt party-in-interest transactions.

As the Plan sponsor, the Company is a party-in-interest with respect to the Plan. At December 31, 2023 and 2022, the Plan held 24,205,000 and 25,162,000 shares of Costco common stock. During 2023, 643,000 shares were purchased and 1,600,000 shares were sold.

9

COSTCO 401(k) RETIREMENT PLAN

Schedule H, Line 4i - Schedule of Assets (Held at End of Year)

EIN: 91-1223280 Plan #: 002

December 31, 2023

(in thousands)

(a) (b) Identity of issuer, borrower, lessor, or similar party			(c) Description of investment	(d) Cost	(e) Current value
Registered investment company and common commingled trust funds:
	Capital Group		New Perspective Trust U3	**	$	477,065
	PIMCO		Income Institutional	**	499,987
	* T. Rowe Price		Retirement Balanced Trust J	**	30,408
	* T. Rowe Price		TRP Ret 2005 Active Trust J	**	21,782
	* T. Rowe Price		TRP Ret 2010 Active Trust J	**	36,126
	* T. Rowe Price		TRP Ret 2015 Active Trust J	**	116,016
	* T. Rowe Price		TRP Ret 2020 Active Trust J	**	372,140
	* T. Rowe Price		TRP Ret 2025 Active Trust J	**	786,144
	* T. Rowe Price		TRP Ret 2030 Active Trust J	**	1,096,452
	* T. Rowe Price		TRP Ret 2035 Active Trust J	**	1,044,923
	* T. Rowe Price		TRP Ret 2040 Active Trust J	**	1,208,119
	* T. Rowe Price		TRP Ret 2045 Active Trust J	**	1,366,606
	* T. Rowe Price		TRP Ret 2050 Active Trust J	**	929,047
	* T. Rowe Price		TRP Ret 2055 Active Trust J	**	1,110,512
	* T. Rowe Price		TRP Ret 2060 Active Trust J	**	537,565
	* T. Rowe Price		TRP Ret 2065 Active Trust J	**	95,198
	* T. Rowe Price		TRP Ret 2020 Active Trust-Income J	**	6,289
	Vanguard		Extended Market Index Institutional	**	74,151
	Vanguard		Total International Stock Index Institutional	**	74,258
	Vanguard		Total Bond Market Index Fund Institutional	**	122,703
	Vanguard		Institutional Index, Plus	**	1,115,488
	Wellington		CIF II Growth S5	**	845,734
	Total registered investment company and common commingled trust funds				11,966,713
Separately managed accounts:
	Mid-Cap Growth Portfolio:
		Acadia Healthcare Company Inc.	Common Stock	**	14,555
		Agilent Technologies Inc.	Common Stock	**	31,406
		Agilon Health Inc.	Common Stock	**	2,646
		Alnylam Pharmaceuticals Inc.	Common Stock	**	14,560
		Amphenol Corp. - Class A	Common Stock	**	12,050
		Apellis Pharmaceuticals Inc.	Common Stock	**	3,583
		Assurant Inc.	Common Stock	**	15,340
		Atlassian Corp. - Class A	Common Stock	**	6,791
		Avantor Inc.	Common Stock	**	20,726
		Avery Dennison Corp.	Common Stock	**	18,103
		Ball Corp.	Common Stock	**	23,532
		Bath & Body Works Inc.	Common Stock	**	11,047
		Bill Holdings Inc.	Common Stock	**	1,829
		Biogen Inc.	Common Stock	**	10,591
		Boston Beer Company Inc. - Class A	Common Stock	**	3,878
		Bright Horizons Family Solutions Inc.	Common Stock	**	4,158
		Broadridge Financial Solutions Inc.	Common Stock	**	12,062
		Bruker Corp.	Common Stock	**	18,115
		Burlington Stores Inc.	Common Stock	**	16,600
		BWX Technologies Inc.	Common Stock	**	6,136

10

COSTCO 401(k) RETIREMENT PLAN

Schedule H, Line 4i – Schedule of Assets (Held at End of Year) (Continued)

December 31, 2023

(in thousands)

(a) (b) Identity of issuer, borrower, lessor, or similar party		(c) Description of investment	(d) Cost	(e) Current value
	Caesars Entertainment Inc.	Common Stock	**	6,316
	Casey's General Stores Inc.	Common Stock	**	11,218
	Catalent Inc.	Common Stock	**	9,447
	Cboe Global Markets Inc.	Common Stock	**	2,371
	CCC Intelligent Solutions Holdings Inc.	Common Stock	**	8,889
	Cheniere Energy Inc.	Common Stock	**	18,047
	Chesapeake Energy Corp.	Common Stock	**	3,464
	Chipotle Mexican Grill Inc.	Common Stock	**	5,479
	Clear Secure Inc. - Class A	Common Stock	**	1,504
	Cognex Corp.	Common Stock	**	4,550
	Cooper Companies Inc.	Common Stock	**	14,356
	Corpay Inc.	Common Stock	**	11,482
	Costar Group Inc.	Common Stock	**	12,728
	Coterra Energy Inc.	Common Stock	**	6,583
	Crowdstrike Holdings Inc. - Class A	Common Stock	**	25,772
	Dentsply Sirona Inc.	Common Stock	**	5,923
	Dollar General Corp.	Common Stock	**	3,365
	Dollar Tree Inc.	Common Stock	**	15,429
	Domino's Pizza Inc.	Common Stock	**	22,020
	Enovis Corp.	Common Stock	**	8,020
	EQT Corp.	Common Stock	**	11,694
	Equifax Inc.	Common Stock	**	20,440
	Esab Corp.	Common Stock	**	12,338
	Exact Sciences Corp.	Common Stock	**	4,778
	Fair Isaac Corp.	Common Stock	**	15,687
	Five Below Inc.	Common Stock	**	11,853
	Fortinet Inc.	Common Stock	**	7,257
	Fortive Corp.	Common Stock	**	14,708
	Hilton Worldwide Holdings Inc.	Common Stock	**	25,158
	Hologic Inc.	Common Stock	**	34,373
	Howmet Aerospace Inc.	Common Stock	**	1,437
	Idex Corp.	Common Stock	**	8,128
	Ingersoll Rand Inc.	Common Stock	**	24,390
	Intercontinental Exchange Inc.	Common Stock	**	15,654
	Ionis Pharmaceuticals Inc.	Common Stock	**	10,777
	J.B. Hunt Transport Services Inc.	Common Stock	**	23,210
	Karuna Therapeutics Inc.	Common Stock	**	9,683
	Kenvue Inc.	Common Stock	**	4,351
	Keysight Technologies Inc.	Common Stock	**	18,359
	KKR & Co Inc.	Common Stock	**	19,990
	KLA Corp.	Common Stock	**	9,791
	Lattice Semiconductor Corp.	Common Stock	**	14,160
	Liberty Media Corp. - Series C	Common Stock	**	8,941
	Littelfuse Inc.	Common Stock	**	2,431
	Lululemon Athletica Inc.	Common Stock	**	6,891
	Markel Group Inc.	Common Stock	**	4,819
	Marketaxess Holdings Inc.	Common Stock	**	7,747

11

COSTCO 401(k) RETIREMENT PLAN

Schedule H, Line 4i – Schedule of Assets (Held at End of Year) (Continued)

December 31, 2023

(in thousands)

(a) (b) Identity of issuer, borrower, lessor, or similar party		(c) Description of investment	(d) Cost	(e) Current value
	Martin Marietta Materials	Common Stock	**	17,834
	Marvell Technology Inc.	Common Stock	**	35,301
	Match Group Inc.	Common Stock	**	4,910
	Mettler-Toldeo International Inc.	Common Stock	**	4,965
	MGM Resorts International	Common Stock	**	7,050
	Microchip Technology Inc.	Common Stock	**	42,663
	Mobileye Global Inc. - Class A	Common Stock	**	1,732
	Molina Healthcare Inc.	Common Stock	**	11,939
	MongoDB Inc.	Common Stock	**	4,490
	New York Times Co. - Class A	Common Stock	**	6,108
	O'Reilly Automotive Inc.	Common Stock	**	1,897
	Paylocity Holding Corp.	Common Stock	**	11,042
	Pioneer Natural Resources Co.	Common Stock	**	2,029
	PTC Inc.	Common Stock	**	20,504
	Pure Storage Inc. - Class A	Common Stock	**	1,606
	Quanta Services Inc.	Common Stock	**	3,836
	Quidelortho Corp.	Common Stock	**	9,524
	Range Resources Corp.	Common Stock	**	5,193
	Raymond James Financial Inc.	Common Stock	**	8,829
	Reynolds Consumer Products Inc.	Common Stock	**	4,681
	Roper Technologies Inc.	Common Stock	**	10,449
	Ross Stores Inc.	Common Stock	**	15,459
	RPM International Inc.	Common Stock	**	6,965
	Sarepta Therapeutics Inc.	Common Stock	**	3,836
	Sealed Air Corp.	Common Stock	**	8,400
	Shoals Technologies Group - Class A	Common Stock	**	1,671
	Southwest Airlines Co.	Common Stock	**	6,550
	Teleflex Inc.	Common Stock	**	29,111
	Textron Inc.	Common Stock	**	24,039
	Tractor Supply Co.	Common Stock	**	3,084
	Trade Desk Inc/The - Class A	Common Stock	**	23,699
	Tradeweb Markets Inc. - Class A	Common Stock	**	14,861
	Transunion	Common Stock	**	9,864
	Treehouse Foods Inc.	Common Stock	**	5,145
	Tyler Technologies Inc.	Common Stock	**	10,143
	Ulta Beauty Inc.	Common Stock	**	7,826
	United Rentals Inc.	Common Stock	**	13,681
	Veeva Systems Inc. - Class A	Common Stock	**	18,564
	Veralto Corp.	Common Stock	**	7,317
	Verisk Analytics Inc.	Common Stock	**	7,535
	West Pharmaceutical Services	Common Stock	**	9,162
	Yum! Brands Inc.	Common Stock	**	14,932
	Alcon AG	Foreign Stock	**	10,949
	Argenx SE - ADR	Foreign Stock	**	7,302
	Ascendis Pharma A/S - ADR	Foreign Stock	**	6,362
	Axis Capital Holdings Ltd.	Foreign Stock	**	3,694
	Birkenstock Holding PLC	Foreign Stock	**	3,084

12

COSTCO 401(k) RETIREMENT PLAN

Schedule H, Line 4i – Schedule of Assets (Held at End of Year) (Continued)

December 31, 2023

(in thousands)

(a) (b) Identity of issuer, borrower, lessor, or similar party			(c) Description of investment	(d) Cost	(e) Current value
		Crispr Therapeutics AG	Foreign Stock	**	3,445
		NXP Semiconductors N.V.	Foreign Stock	**	6,909
		Spotify Technology SA	Foreign Stock	**	18,459
		TechnipFMC PLC	Foreign Stock	**	9,931
		Waste Connections Inc.	Foreign Stock	**	4,605
		Weatherford International PLC	Foreign Stock	**	1,543
		Caris Life, Series D Convertible	Preferred Stock	**	462
		Databricks, Series H Convertible	Preferred Stock	**	726
		Databricks, Series I Convertible	Preferred Stock	**	309
		Maplebear Dba Instacart, Series E Convertible	Preferred Stock	**	524
		Nuro, Series D Convertible	Preferred Stock	**	139
		Redwood Materials, Series C Convertible	Preferred Stock	**	768
		Sila Nanotechnologies Inc., Series F Convertible	Preferred Stock	**	692
		Cash	Cash	**	9
		*Northern Institutional Treasury Portfolio Premier Shares	Money Market Securities	**	1,317
		*T.Rowe Price Treasury Reserve Fund	Money Market Securities	**	25,410
	Large Cap Value Portfolio:
		Adobe Inc.	Common Stock	**	342
		Agilent Technologies Inc.	Common Stock	**	682
		Allstate Corp.	Common Stock	**	3,811
		Alphabet Inc. - Class C	Common Stock	**	1,878
		Ameren Corporation	Common Stock	**	3,155
		American Express Company	Common Stock	**	5,007
		Ametek Inc.	Common Stock	**	3,842
		Amgen Inc.	Common Stock	**	4,331
		Amphenol Corp. - Class A	Common Stock	**	1,947
		Analog Devices Inc.	Common Stock	**	2,204
		Applied Materials Inc.	Common Stock	**	3,931
		Autozone Inc.	Common Stock	**	3,306
		Bank of America Corp.	Common Stock	**	8,994
		Becton, Dickinson and Co.	Common Stock	**	837
		Berkshire Hathaway Inc. - Class B	Common Stock	**	14,466
		Booking Holdings Inc.	Common Stock	**	4,252
		Carrier Global Corporation	Common Stock	**	2,134
		Caterpillar Inc.	Common Stock	**	325
		Cencora Inc.	Common Stock	**	8,071
		Charles Schwab Corporation	Common Stock	**	4,251
		Chevron Corp.	Common Stock	**	5,312
		CME Group Inc.	Common Stock	**	3,647
		Coca-Cola Co/The	Common Stock	**	2,644
		Colgate-Palmolive Company	Common Stock	**	3,220
		Conocophillips	Common Stock	**	5,733
		Constellation Brands Inc. - Class A	Common Stock	**	4,752
		Corebridge Financial Inc.	Common Stock	**	1,399
		Corpay Inc.	Common Stock	**	1,623

13

COSTCO 401(k) RETIREMENT PLAN

Schedule H, Line 4i – Schedule of Assets (Held at End of Year) (Continued)

December 31, 2023

(in thousands)

(a) (b) Identity of issuer, borrower, lessor, or similar party		(c) Description of investment	(d) Cost	(e) Current value
	CSX Corp.	Common Stock	**	6,603
	Cummins Inc.	Common Stock	**	3,328
	Danaher Corp.	Common Stock	**	2,977
	Deere & Company	Common Stock	**	1,605
	Diamondback Energy Inc.	Common Stock	**	1,426
	Dover Corp.	Common Stock	**	830
	East West Bancorp Inc.	Common Stock	**	897
	Elevance Health Inc.	Common Stock	**	11,947
	EQT Corp.	Common Stock	**	4,846
	Equity Lifestyle Properties	Common Stock	**	2,369
	Extra Space Storage Inc.	Common Stock	**	1,284
	Exxon Mobil Corp.	Common Stock	**	4,389
	Firstenergy Corp.	Common Stock	**	832
	Fiserv Inc.	Common Stock	**	8,551
	Freeport-McMoRan Inc.	Common Stock	**	3,744
	GE Healthcare Technologies Inc.	Common Stock	**	3,834
	General Dynamics Corp.	Common Stock	**	3,687
	General Electric Co.	Common Stock	**	6,311
	Goldman Sachs Group Inc.	Common Stock	**	4,004
	Halliburton Company	Common Stock	**	4,991
	Hartford Financial Service Group Inc.	Common Stock	**	1,897
	HCA Healthcare Inc.	Common Stock	**	3,439
	Hilton Worldwide Holdings Inc.	Common Stock	**	1,274
	Home Depot Inc.	Common Stock	**	2,223
	Humana Inc.	Common Stock	**	1,759
	IDEX Corp.	Common Stock	**	2,431
	Intel Corp.	Common Stock	**	3,065
	Johnson & Johnson	Common Stock	**	5,283
	JPMorgan Chase & Co.	Common Stock	**	13,105
	Kenvue Inc.	Common Stock	**	7,075
	Kinder Morgan Inc.	Common Stock	**	2,956
	Kraft Heinz Co/The	Common Stock	**	1,170
	L3Harris Technologies Inc.	Common Stock	**	3,717
	Lam Research Corp.	Common Stock	**	3,885
	Martin Marietta Materials Inc.	Common Stock	**	1,234
	McDonald's Corp.	Common Stock	**	3,886
	Medtronic PLC	Common Stock	**	2,309
	Merck & Co. Inc.	Common Stock	**	4,951
	Metlife Inc.	Common Stock	**	5,142
	Micron Technologies Inc.	Common Stock	**	3,544
	Mircrosoft Corp.	Common Stock	**	1,807
	Mondelez International Inc. - Class A	Common Stock	**	7,032
	NextEra Energy Inc.	Common Stock	**	4,551
	Norfolk Southern Corp.	Common Stock	**	2,531
	Northrop Grumman Corp.	Common Stock	**	1,492
	Norwegian Cruise Line Holdings Ltd.	Common Stock	**	1,004
	NOV Inc.	Common Stock	**	460

14

COSTCO 401(k) RETIREMENT PLAN

Schedule H, Line 4i – Schedule of Assets (Held at End of Year) (Continued)

December 31, 2023

(in thousands)

(a) (b) Identity of issuer, borrower, lessor, or similar party			(c) Description of investment	(d) Cost	(e) Current value
		NRG Energy Inc.	Common Stock	**	925
		PepsiCo Inc.	Common Stock	**	2,236
		Philip Morris International Inc.	Common Stock	**	6,475
		Pioneer Natural Resources Company	Common Stock	**	607
		PNC Financial Services Group Inc.	Common Stock	**	3,299
		Proctor & Gamble Co/The	Common Stock	**	6,484
		Progressive Corp.	Common Stock	**	3,975
		Prolongis Inc.	Common Stock	**	2,461
		Public Storage	Common Stock	**	3,903
		Qualcomm Inc.	Common Stock	**	4,251
		Range Resources Corp.	Common Stock	**	3,880
		Regeneron Pharmaceuticals Inc.	Common Stock	**	131
		Salesforce Inc.	Common Stock	**	1,973
		Schlumberger Ltd.	Common Stock	**	4,124
		Service Corporation International	Common Stock	**	1,588
		Southern Co/The	Common Stock	**	2,207
		TE Connectivity Ltd.	Common Stock	**	2,787
		Tenet Healthcare Corp.	Common Stock	**	2,205
		Texas Instruments Corp.	Common Stock	**	6,331
		Thermo Fisher Scientific Inc.	Common Stock	**	3,064
		T-Mobile US Inc.	Common Stock	**	4,392
		Tractor Supply Company	Common Stock	**	1,139
		Travelers Cos Inc/The	Common Stock	**	5,122
		Ulta Beauty Inc.	Common Stock	**	2,552
		Union Pacific Corp.	Common Stock	**	5,699
		UnitedHealth Group Inc.	Common Stock	**	1,625
		Veralto Corp.	Common Stock	**	1,348
		Visa Inc. - Class A	Common Stock	**	1,432
		Walmart Inc.	Common Stock	**	5,841
		Wells Fargo & Co.	Common Stock	**	6,438
		Wabtec Corp.	Common Stock	**	4,825
		Weyerhaeuser Co.	Common Stock	**	2,672
		Williams Companies Inc.	Common Stock	**	1,339
		Astrazeneca PLC - Sponsored ADR	Foreign Stock	**	4,050
		Chubb Ltd.	Foreign Stock	**	2,704
		Franco-Nevada Corp.	Foreign Stock	**	1,352
		Linde PLC	Foreign Stock	**	4,312
		Nutrien Ltd.	Foreign Stock	**	1,272
		NXP Semiconductors NV	Foreign Stock	**	5,362
		Siemens AG	Foreign Stock	**	3,125
		Southern Copper Corp.	Foreign Stock	**	1,069
		Wheaton Precious Metals Corp.	Foreign Stock	**	1,919
		Cash	Cash	**	12
		*Northern Institutional Treasury Portfolio	Money Market Securities	**	1,004
		*T. Rowe Price Government Reserve Fund	Money Market Securities	**	7,096
	Small-Cap Core Portfolio:
		10X Genomics Inc. - Class A	Common Stock	**	1,651

15

COSTCO 401(k) RETIREMENT PLAN

Schedule H, Line 4i – Schedule of Assets (Held at End of Year) (Continued)

December 31, 2023

(in thousands)

(a) (b) Identity of issuer, borrower, lessor, or similar party		(c) Description of investment	(d) Cost	(e) Current value
	AAON Inc.	Common Stock	**	1,550
	Agilysys Inc.	Common Stock	**	1,810
	Agios Pharmaceuticals Inc.	Common Stock	**	533
	Alignment Healthcare Inc.	Common Stock	**	1,395
	Allegiant Travel Co.	Common Stock	**	1,265
	Allegro Microsystems Inc.	Common Stock	**	1,295
	Altair Engineering Inc. - Class A	Common Stock	**	2,010
	Amplitude Inc. - Class A	Common Stock	**	1,990
	Apellis Pharmaceuticals Inc.	Common Stock	**	3,605
	Arcellx Inc.	Common Stock	**	1,159
	Arcosa Inc.	Common Stock	**	1,462
	ASGN Inc.	Common Stock	**	990
	Assurant Inc.	Common Stock	**	3,728
	Avid Bioservices Inc.	Common Stock	**	725
	Azenta Inc.	Common Stock	**	536
	AZZ Inc.	Common Stock	**	3,506
	BankUnited Inc.	Common Stock	**	1,782
	Beacon Roofing Supply Inc.	Common Stock	**	3,040
	Bellring Brands Inc.	Common Stock	**	5,219
	BJ's Restaurants Inc.	Common Stock	**	2,185
	Blue Foundry Bancorp.	Common Stock	**	365
	Blueprint Medicines Corp.	Common Stock	**	2,398
	Booz Allen Hamilton Holdings	Common Stock	**	1,102
	Boston Beer Company Inc. - Class A	Common Stock	**	3,336
	Braze Inc. - Class A	Common Stock	**	764
	BridgeBio Pharma Inc.	Common Stock	**	1,029
	Bright Horizons Family Solutions	Common Stock	**	3,280
	Bruker Corp.	Common Stock	**	3,689
	Burlington Stores Inc.	Common Stock	**	5,319
	Cabaletta Bio Inc.	Common Stock	**	543
	Cadence Bank	Common Stock	**	2,324
	Cadre Holdings Inc.	Common Stock	**	863
	Caleres Inc.	Common Stock	**	1,563
	California Water Services Group	Common Stock	**	2,033
	Capitol Federal Financial Inc.	Common Stock	**	1,072
	Casella Waste Systems Inc. - Class A	Common Stock	**	2,580
	Catalent Inc.	Common Stock	**	1,793
	Cava Group Inc.	Common Stock	**	2,144
	Cboe Global Markets Inc.	Common Stock	**	3,987
	Certara Inc.	Common Stock	**	1,096
	ChampionX Corp.	Common Stock	**	2,374
	Checkr Inc.	Common Stock	**	137
	Chesapeake Utilities Corp.	Common Stock	**	3,905
	Chuy's Holdings Inc.	Common Stock	**	1,523
	Clear Secure Inc. - Class A	Common Stock	**	1,672
	Coca-Cola Consolidated Inc.	Common Stock	**	11
	Cognex Corp.	Common Stock	**	526

16

COSTCO 401(k) RETIREMENT PLAN

Schedule H, Line 4i – Schedule of Assets (Held at End of Year) (Continued)

December 31, 2023

(in thousands)

(a) (b) Identity of issuer, borrower, lessor, or similar party		(c) Description of investment	(d) Cost	(e) Current value
	Columbia Banking Systems Inc.	Common Stock	**	2,399
	Community Healthcare Trust Inc.	Common Stock	**	46
	Crane Co.	Common Stock	**	1,794
	CRB Group Inc.	Common Stock	**	96
	Crinetics Pharmaceuticals Inc.	Common Stock	**	1,545
	Crossfirst Bankshares Inc.	Common Stock	**	982
	CSW Industrials Inc.	Common Stock	**	3,164
	CTS Corp.	Common Stock	**	1,908
	Cubesmart	Common Stock	**	3,441
	Cytokinetics Inc.	Common Stock	**	3,312
	Diamondback Energy Inc.	Common Stock	**	4,805
	Digitalbridge Group Inc.	Common Stock	**	1,478
	Dime Community Bancshares Inc.	Common Stock	**	1,428
	Dogwood State Bank, Non-Voting	Common Stock	**	233
	Dogwood State Bank, Voting	Common Stock	**	114
	Doubleverify Holdings Inc.	Common Stock	**	4,072
	DT Midstream Inc.	Common Stock	**	1,767
	Duolingo Inc.	Common Stock	**	2,467
	Dutch Bros Inc. - Class A	Common Stock	**	2,023
	East West Bancorp Inc.	Common Stock	**	3,642
	Eastern Bankshares Inc.	Common Stock	**	1,293
	Eastgroup Properties Inc.	Common Stock	**	5,652
	Elanco Animal Health Inc.	Common Stock	**	1,705
	Element Solutions Inc.	Common Stock	**	6,017
	Encore Capital Group Inc.	Common Stock	**	1,417
	Enerpac Tool Group Corp.	Common Stock	**	2,637
	Enpro Inc.	Common Stock	**	1,973
	Entegris Inc.	Common Stock	**	4,539
	Envestnet Inc.	Common Stock	**	1,618
	Equity Bancshares Inc. - Class A	Common Stock	**	1,216
	Esab Corp.	Common Stock	**	1,934
	Esco Technologies Inc.	Common Stock	**	2,271
	Expro Group Holdings NV	Common Stock	**	1,195
	Eyepoint Pharmaceuticals Inc.	Common Stock	**	468
	FB Financial Corp.	Common Stock	**	1,904
	Federal Signal Corp.	Common Stock	**	4,641
	First American Financial Corp.	Common Stock	**	2,704
	First Bancshares Inc/Ms	Common Stock	**	1,481
	Five Below Inc.	Common Stock	**	1,777
	Five Star Bancorp	Common Stock	**	921
	Five9 Inc.	Common Stock	**	2,608
	Floor & Décor Holdings Inc. - Class A	Common Stock	**	784
	Graco Inc.	Common Stock	**	2,530
	Grasshopper Bancorp, Voting	Common Stock	**	65
	Guardant Health Inc.	Common Stock	**	702
	H.B. Fuller Company	Common Stock	**	1,422
	Haemonetics Corporation	Common Stock	**	2,042

17

COSTCO 401(k) RETIREMENT PLAN

Schedule H, Line 4i – Schedule of Assets (Held at End of Year) (Continued)

December 31, 2023

(in thousands)

(a) (b) Identity of issuer, borrower, lessor, or similar party		(c) Description of investment	(d) Cost	(e) Current value
	Hanover Insurance Group Inc/The	Common Stock	**	2,664
	HarborOne Bancorp Inc.	Common Stock	**	372
	Haul Hub, Series C Convertible	Common Stock	**	36
	Haynes International Inc.	Common Stock	**	2,171
	Healthcare Realty Trust Inc.	Common Stock	**	1,036
	Helios Technologies Inc.	Common Stock	**	1,499
	Heritage Commerce Corp.	Common Stock	**	702
	Hillevax Inc.	Common Stock	**	261
	Home Bancshares Inc.	Common Stock	**	1,507
	Icosavax Inc.	Common Stock	**	687
	ICU Medical Inc.	Common Stock	**	1,240
	Idacorp Inc.	Common Stock	**	2,955
	Independence Realty Trust Inc.	Common Stock	**	1,891
	Ingersoll Rand Inc.	Common Stock	**	6,663
	Insmed Inc.	Common Stock	**	2,766
	Installed Building Products Inc.	Common Stock	**	1,519
	Intapp Inc.	Common Stock	**	1,533
	Ionis Pharmaceuticals Inc.	Common Stock	**	2,143
	Jack in the Box Inc.	Common Stock	**	1,118
	John Bean Technologies Corp.	Common Stock	**	2,320
	Karuna Therapeutics Inc.	Common Stock	**	4,302
	Kearny Financial Corp/Md	Common Stock	**	672
	Kimbell Royalty Partners, LP	Common Stock	**	898
	Kohls Corp.	Common Stock	**	1,049
	Kymera Therapeutics Inc.	Common Stock	**	345
	Landstar System Inc.	Common Stock	**	1,941
	Lattice Semiconductor Corp.	Common Stock	**	3,870
	LegalZoom.com Inc.	Common Stock	**	974
	Leonardo DRS Inc.	Common Stock	**	1,601
	Liberty Energy Inc.	Common Stock	**	2,573
	Liberty Media Corp., Series C	Common Stock	**	2,122
	Littelfuse Inc.	Common Stock	**	2,653
	Live Oak Bancshares Inc.	Common Stock	**	2,756
	MACOM Technology Solutions Holdings Inc.	Common Stock	**	3,288
	MacroGenics Inc.	Common Stock	**	733
	Magnolia Oil & Gas Corp. - Class A	Common Stock	**	2,451
	Manhattan Associates Inc.	Common Stock	**	1,820
	Masimo Corp.	Common Stock	**	3,467
	Matador Resources Co.	Common Stock	**	1,398
	MGE Energy Inc.	Common Stock	**	1,258
	Mirion Technologies Inc. - Class A	Common Stock	**	3,103
	Model N Inc.	Common Stock	**	756
	Molina Healthcare Inc.	Common Stock	**	4,634
	Monro Inc.	Common Stock	**	1,610
	Mueller Water Products Inc.	Common Stock	**	2,182
	Napco Security Technologies	Common Stock	**	1,435
	Neogen Corp.	Common Stock	**	2,399

18

COSTCO 401(k) RETIREMENT PLAN

Schedule H, Line 4i – Schedule of Assets (Held at End of Year) (Continued)

December 31, 2023

(in thousands)

(a) (b) Identity of issuer, borrower, lessor, or similar party		(c) Description of investment	(d) Cost	(e) Current value
	Neogenomics Inc.	Common Stock	**	2,605
	NOV Inc.	Common Stock	**	1,548
	NV5 Global Inc.	Common Stock	**	633
	OGE Energy Corp.	Common Stock	**	1,756
	Ollie's Bargain Outlet Holdings Inc.	Common Stock	**	2,905
	One Gas Inc.	Common Stock	**	948
	Onto Innovation Inc.	Common Stock	**	4,467
	Origin Bancorp Inc.	Common Stock	**	2,042
	Outset Medical Inc.	Common Stock	**	443
	P10 Inc. - Class A	Common Stock	**	1,447
	Pacific Biosciences of California Inc.	Common Stock	**	1,770
	Pacific Premier Bancorp Inc.	Common Stock	**	1,513
	Papa John's International Inc.	Common Stock	**	4,547
	PAR Technology Corp/Del	Common Stock	**	4,535
	Parsons Corp.	Common Stock	**	3,757
	Pax Labs - Class A	Common Stock	**	67
	Paycor HCM Inc.	Common Stock	**	2,388
	Pennymac Financial Services	Common Stock	**	5,245
	Penumbra Inc.	Common Stock	**	444
	Pinnacle Financial Partners	Common Stock	**	3,046
	Post Holdings Inc.	Common Stock	**	2,457
	Power Integrations Inc.	Common Stock	**	1,152
	PRA Group Inc.	Common Stock	**	996
	Privia Health Group Inc.	Common Stock	**	2,787
	Procept Biorobotics Corp.	Common Stock	**	3,520
	Prosperity Bancshares Inc.	Common Stock	**	437
	Quaker Chemical Corporation	Common Stock	**	2,892
	Quidelortho Corp.	Common Stock	**	2,635
	Range Resources Corp.	Common Stock	**	3,891
	Rapt Therapeutics Inc.	Common Stock	**	672
	RBC Bearings Inc.	Common Stock	**	4,947
	Red Rock Resorts Inc. - Class A	Common Stock	**	1,693
	Repligen Corp.	Common Stock	**	1,475
	Rexford Industrial Realty Inc.	Common Stock	**	3,121
	RH	Common Stock	**	1,008
	Rivian Automotive Inc.	Common Stock	**	1,811
	RLI Corp.	Common Stock	**	545
	Royal Gold Inc.	Common Stock	**	1,305
	Rush Enterprises Inc. - Class A	Common Stock	**	2,189
	Rxsight Inc.	Common Stock	**	756
	Saia Inc.	Common Stock	**	4,921
	Savers Value Village Inc.	Common Stock	**	571
	Selective Insurance Group Inc.	Common Stock	**	5,218
	Service Titan Inc.	Common Stock	**	80
	Simply Good Foods Co/The	Common Stock	**	1,239
	Siteone Landscape Supply Inc.	Common Stock	**	3,981
	Skechers U.S.A. Inc. - Class A	Common Stock	**	1,745

19

COSTCO 401(k) RETIREMENT PLAN

Schedule H, Line 4i – Schedule of Assets (Held at End of Year) (Continued)

December 31, 2023

(in thousands)

(a) (b) Identity of issuer, borrower, lessor, or similar party		(c) Description of investment	(d) Cost	(e) Current value
	Skyline Champion Corp.	Common Stock	**	2,801
	SM Energy Co.	Common Stock	**	1,018
	Sotera Health Co.	Common Stock	**	1,342
	SouthState Corp.	Common Stock	**	3,152
	Southwest Gas Holdings Inc.	Common Stock	**	2,306
	Southwestern Energy Co.	Common Stock	**	3,142
	SPX Technologies Inc.	Common Stock	**	4,082
	Stepstone Group Inc. - Class A	Common Stock	**	1,644
	Stericycle Inc.	Common Stock	**	1,982
	Strategic Education Inc.	Common Stock	**	2,790
	Structure Therapeutics Inc. - ADR	Common Stock	**	999
	Syndax Pharmaceuticals Inc.	Common Stock	**	593
	Teledyne Technologies Inc.	Common Stock	**	4,410
	Terreno Realty Corp.	Common Stock	**	1,469
	Tetra Tech Inc.	Common Stock	**	1,784
	Texas Capital Bancshares Inc.	Common Stock	**	1,598
	Themis Sol (Clio), Series E Convertible	Common Stock	**	356
	Themis Solutions Inc.	Common Stock	**	125
	Thermon Group Holdings Inc.	Common Stock	**	887
	Toast Inc. - Class A	Common Stock	**	1,429
	Toro Co.	Common Stock	**	1,790
	Transcat Inc.	Common Stock	**	440
	Treehouse Foods Inc.	Common Stock	**	786
	U.S. Physical Therapy Inc.	Common Stock	**	1,619
	UTZ Brands Inc. - Class A	Common Stock	**	1,549
	Vaxcyte Inc.	Common Stock	**	1,721
	Veritex Holdings Inc.	Common Stock	**	1,297
	Verve Therapeutics Inc.	Common Stock	**	603
	Vimeo Inc.	Common Stock	**	1,075
	Vontier Corp.	Common Stock	**	2,162
	VSE Corp.	Common Stock	**	1,751
	Warby Parker Inc. - Class A	Common Stock	**	1,819
	Western Alliance Bancorporation	Common Stock	**	2,158
	White Mountains Insurance Group Ltd.	Common Stock	**	1,775
	Willscot Mobile Mini Holdings Corp.	Common Stock	**	1,845
	Workiva Inc. - Class A	Common Stock	**	3,341
	Wyndham Hotels & Resorts Inc.	Common Stock	**	2,020
	Zentalis Pharmaceuticals Inc.	Common Stock	**	432
	Zurn Elkay Water Solutions Corp.	Common Stock	**	2,101
	Argenx SE - ADR	Foreign Stock	**	2,616
	Ascendis Pharma A/S - ADR	Foreign Stock	**	3,476
	ATS Corp.	Foreign Stock	**	523
	Axis Capital Holdings Inc.	Foreign Stock	**	3,590
	Bombardier Inc.	Foreign Stock	**	782
	Clarivate PLC	Foreign Stock	**	1,683
	Colliers International Group Inc.	Foreign Stock	**	1,987
	Constellium SE	Foreign Stock	**	3,707

20

COSTCO 401(k) RETIREMENT PLAN

Schedule H, Line 4i – Schedule of Assets (Held at End of Year) (Continued)

December 31, 2023

(in thousands)

(a) (b) Identity of issuer, borrower, lessor, or similar party		(c) Description of investment	(d) Cost	(e) Current value
	Crispr Therapeutics AG	Foreign Stock	**	971
	Descartes Systems Group/The	Foreign Stock	**	3,943
	Ero Copper Corp.	Foreign Stock	**	1,269
	Firstservice Corp.	Foreign Stock	**	5,257
	Flagship Communities REIT UT	Foreign Stock	**	541
	Immatics NV	Foreign Stock	**	431
	Immunocore Holdings PLC - ADR	Foreign Stock	**	649
	MoonLake Immunotherapeutics	Foreign Stock	**	1,307
	MorphoSys AG - ADR	Foreign Stock	**	1,001
	Novanta Inc.	Foreign Stock	**	2,249
	Popular Inc.	Foreign Stock	**	1,591
	Rentokil Initial PLC	Foreign Stock	**	2,093
	Spirax Sarco Engineering - ADR	Foreign Stock	**	1,440
	TechnipFMC PLC	Foreign Stock	**	2,117
	TMX Group Ltd.	Foreign Stock	**	1,899
	Tricon Residential Inc.	Foreign Stock	**	1,885
	Weatherford International PLC	Foreign Stock	**	2,415
	West Fraser Timber Co. Ltd.	Foreign Stock	**	1,127
	Xenon Pharmaceuticals Inc.	Foreign Stock	**	666
	1661 Inc. D/B/A/ Goat, Series F Convertible	Preferred Stock	**	107
	ABL Space Systems, Series B	Preferred Stock	**	236
	Caris Life Sciences, Series C Convertible	Preferred Stock	**	283
	Caris Life Sciences, Series D Convertible	Preferred Stock	**	5,428
	Caris Life Sciences, Series D Convertible	Preferred Stock	**	190
	Cellink Inc., Series D Convertible	Preferred Stock	**	41
	Checker Inc., Series C Convertible	Preferred Stock	**	187
	Checker Inc., Series D Convertible	Preferred Stock	**	292
	Cleerly, Series C Convertible	Preferred Stock	**	193
	CRB Group, Series D Convertible	Preferred Stock	**	337
	Dogwood State Bank	Preferred Stock	**	16
	Epirus Inc., Series C-2 Convertible	Preferred Stock	**	534
	Farmers Business Network Inc.	Preferred Stock	**	157
	Flexe, Series C Convertible	Preferred Stock	**	155
	Flexe, Series D Convertible	Preferred Stock	**	61
	Haul Hub, Series B Convertible	Preferred Stock	**	102
	Honor Technology Inc. - Series D	Preferred Stock	**	205
	Inscripta Inc. - Series E	Preferred Stock	**	99
	Kardium Inc., Series D-6 Convertible	Preferred Stock	**	218
	KoBold Metals Co., Series B-1	Preferred Stock	**	489
	Leap Therapeutics Inc.	Preferred Stock	**	3
	National Resilence, Series B Convertible	Preferred Stock	**	1,454
	National Resilence, Series C Convertible	Preferred Stock	**	839
	Nuro Inc., Series C	Preferred Stock	**	175
	Nuro Inc., Series D	Preferred Stock	**	56
	Redwood Materials Inc., Series C	Preferred Stock	**	375
	SecurityScorecard Inc., Series E Convertible	Preferred Stock	**	276
	Seismic Software Inc.	Preferred Stock	**	446

21

COSTCO 401(k) RETIREMENT PLAN

Schedule H, Line 4i – Schedule of Assets (Held at End of Year) (Continued)

December 31, 2023

(in thousands)

(a) (b) Identity of issuer, borrower, lessor, or similar party			(c) Description of investment	(d) Cost	(e) Current value
		ServiceTitan Inc., Series A-1 Convertible	Preferred Stock	**	1
		ServiceTitan Inc., Series D Convertible	Preferred Stock	**	583
		ServiceTitan Inc., Series F Convertible	Preferred Stock	**	35
		Sila Nanotechnologies Inc., Series F	Preferred Stock	**	230
		Socure Inc.	Preferred Stock	**	41
		Socure Inc., Series A Convertible	Preferred Stock	**	50
		Socure Inc., Series A-1 Convertible	Preferred Stock	**	41
		Socure Inc., Series B Convertible	Preferred Stock	**	1
		Socure Inc., Series E Convertible	Preferred Stock	**	95
		Themis Sol (Clio), Series AA Convertible	Preferred Stock	**	28
		Themis Sol (Clio), Series AB Convertible	Preferred Stock	**	3
		Themis Sol (Clio), Series B Convertible	Preferred Stock	**	3
		Cash	Cash	**	281
		*Northern Institutional Treasury Portfolio Premier Shares	Money Market Securities	**	722
		*T.Rowe Price Treasury Reserve Fund	Money Market Securities	**	4,517
		Grasshopper Bancorp Inc.	Warrants	**	1
		Scholar Rock	Warrants	**	59
	International Equity Portfolio:
		Capital Group International All Country Equity Trust	Common Trust	**	188,650
		*Northern Institutional Treasury Portfolio Premier Shares	Money Market Securities	**	80
	Total separately managed accounts				2,491,563
Fully Benefit-Responsive Contracts:
	Capital Preservation Portfolio:
		* T. Rowe Price Cash Reserve Trust	Common Trust	**	21,002
		* Northern Institutional Treasury Portfolio Premier Shares	Common Trust	**	31,468
		* T. Rowe Price Short Term Common Trust:
		American General Life Insurance Company	Collective Trust Fund	**	62,038
		Lincoln National Life Insurance	Collective Trust Fund	**	70,526
		Massachusetts Mutual Life Insurance Company	Collective Trust Fund	**	75,950
		Met Tower Life Insurance	Collective Trust Fund	**	69,220
		Monumental Life(Transamerica)	Collective Trust Fund	**	63,653
		New York Life	Collective Trust Fund	**	75,947
		Pacific Life Insurance Company	Collective Trust Fund	**	75,191
		Prudential Insurance Company of America	Collective Trust Fund	**	75,195
		Royal Bank of Canada	Collective Trust Fund	**	62,922
		State Street Bank & Trust Company	Collective Trust Fund	**	64,403
		* T. Rowe Price Intermediate Term Common Trust:
		American General Life Insurance Company	Collective Trust Fund	**	56,445
		Lincoln National Life Insurance	Collective Trust Fund	**	64,169
		Massachusetts Mutual Life Insurance Company	Collective Trust Fund	**	94,640
		Met Tower Life Insurance	Collective Trust Fund	**	119,313
		Monumental Life(Transamerica)	Collective Trust Fund	**	57,915

22

COSTCO 401(k) RETIREMENT PLAN

Schedule H, Line 4i – Schedule of Assets (Held at End of Year) (Continued)

December 31, 2023

(in thousands)

(a) (b) Identity of issuer, borrower, lessor, or similar party			(c) Description of investment	(d) Cost	(e) Current value
		New York Life	Collective Trust Fund	**	94,637
		Pacific Life Insurance Company	Collective Trust Fund	**	93,694
		Prudential Insurance Company of America	Collective Trust Fund	**	93,699
		Royal Bank of Canada	Collective Trust Fund	**	57,250
		State Street Bank & Trust Company	Collective Trust Fund	**	111,011
		* T. Rowe Price Managed Bond Trust:
		American General Life Insurance Company	Collective Trust Fund	**	14,674
		Lincoln National Life Insurance	Collective Trust Fund	**	16,682
		Massachusetts Mutual Life Insurance Company	Collective Trust Fund	**	21,106
		Met Tower Life Insurance	Collective Trust Fund	**	23,278
		Monumental Life(Transamerica)	Collective Trust Fund	**	15,056
		New York Life	Collective Trust Fund	**	21,105
		Pacific Life Insurance Company	Collective Trust Fund	**	20,895
		Prudential Insurance Company of America	Collective Trust Fund	**	20,896
		Royal Bank of Canada	Collective Trust Fund	**	14,883
		State Street Bank & Trust Company	Collective Trust Fund	**	21,658
	Total fully benefit-responsive contracts				1,780,521
	* Costco Wholesale Corporation		Common stock	**	15,977,459
Total investments					32,216,256
* Participant loans			Interest rates of 4.25% to 10.50% maturing through 2038	__	559,994
Total					$	32,776,250
_________________________
* Indicates a party-in-interest
** Information is not required as investments are participant directed

See accompanying report of independent registered public accounting firm.

23

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the trustees (or other persons who administer the employee benefit plan) have duly caused this annual report to be signed on its behalf by the undersigned hereunto duly authorized.

		COSTCO 401(k) RETIREMENT PLAN
June 20, 2024	By:	/s/ PATRICK J. CALLANS
Date		Patrick J. Callans Executive Vice President Costco Wholesale Corporation

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