Company: COST
Filing Date: 2025-06-27
Form Type: 11-K
Source: 0000909832-25-000038
Chunk: 0

Company: COSTCO WHOLESALE CORP /NEW
Filing Date: 2025-06-27
Form: 11-K
Chunk 0
---
### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION

#### WASHINGTON, D.C. 20549
#### ———————————————————

#### FORM 11-K
#### ———————————————————

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

#### For the fiscal year ended December 31, 2024
| ☐ |     | 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: |

#### ———————————————————

#### Costco Wholesale Corporation
#### ———————————————————

#### 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, 2024 and 2023               |     |    2 |
| Statement of Changes in Net Assets Available for Benefits for the Year Ended December 31, 2024 |     |    3 |
| Notes to Financial Statements                                                                  |     |    4 |
| Supplementary Information:                                                                     |     |      |
| Schedule H, Line 4i - Schedule of Assets (Held at End of Year) as of December 31, 2024         |     |   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