Company: WBS-PG
Filing Date: 2025-06-26
Form Type: 11-K
Source: 0000801337-25-000059
Chunk: 0

Company: WEBSTER FINANCIAL CORP
Filing Date: 2025-06-26
Form: 11-K
Chunk 0
---
### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549
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#### FORM 11-K
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#### OR
| o |     | TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 |
|   |     | For the transition period from _____ to _____                                      |

#### Commission file number 001-31486
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| A. |     | Full title of the plan and the address of the plan, if different from that of the issuer named below: |

#### Webster Bank Retirement Savings Plan
| B. |     | Name of issuer of the securities held pursuant to the plan and the address of its principal executive office: |

### Webster Financial Corporation

#### 200 Elm Street

#### Stamford, CT 06902

### WEBSTER BANK RETIREMENT SAVINGS PLAN

### FINANCIAL STATEMENTS AND SUPPLEMENTAL SCHEDULE

### TABLE OF CONTENTS
|                                                                                                                                                                                                                                                   |     | Page |
| Report of Independent Registered Public Accounting Firm                                                                                                                                                                                           |     |    1 |
| Financial Statements:                                                                                                                                                                                                                             |     |      |
| Statements of Net Assets Available for Benefits                                                                                                                                                                                                   |     |    2 |
| Statements of Changes in Net Assets Available for Benefits                                                                                                                                                                                        |     |    3 |
| Notes to Financial Statements                                                                                                                                                                                                                     |     |    4 |
| Supplemental Schedule:                                                                                                                                                                                                                            |     |      |
| Schedule H, Line 4(i) - Schedule of Assets (Held At End of Year)                                                                                                                                                                                  |     |   10 |
| All other schedules required by Section 2520.103-10 of the Department of Labor’s Rules and Regulations for Reporting and Disclosure under the Employee Retirement Income Security Act of 1974 have been omitted because they were not applicable. |     |      |
| Exhibit Index                                                                                                                                                                                                                                     |     |   11 |
| Signatures                                                                                                                                                                                                                                        |     |   12 |

<div align='center'>Report of Independent Registered Public Accounting Firm</div>

To the Retirement Plans Committee of

Webster Bank Retirement Savings Plan

### Opinion on the Financial Statements
We have audited the accompanying statements of net assets available for benefits of the Webster Bank Retirement Savings Plan (the Plan) as of December 31, 2024