Company: ASB
Filing Date: 2025-06-27
Form Type: 11-K
Source: 0000007789-25-000097
Chunk: 0

Company: ASSOCIATED BANC-CORP
Filing Date: 2025-06-27
Form: 11-K
Chunk 0
---
### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549

#### FORM 11-K
| ý |     | ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 |

<div align='center'>For the fiscal year ended December 31, 2024</div>

#### OR
| ¨ |     | TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 |

<div align='center'>For the transition period from __________ to __________

Commission file number 001-31343 (Associated Banc-Corp)</div>

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

<div align='center'>ASSOCIATED BANC-CORP 401(k) & EMPLOYEE STOCK OWNERSHIP PLAN</div>

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

### ASSOCIATED BANC-CORP

#### 433 Main Street

#### Green Bay, Wisconsin 54301
<div align='center'>ASSOCIATED BANC-CORP

401(k) & EMPLOYEE STOCK OWNERSHIP PLAN

Financial Statements and Schedule

December 31, 2024 and 2023

(With Report of Independent Registered Public Accounting Firm Thereon)</div>

### ASSOCIATED BANC-CORP

#### 401(k) & EMPLOYEE STOCK OWNERSHIP PLAN

#### Table of Contents
|                                                                                   |     |   |     | Page |
| Report of Independent Registered Public Accounting Firm                           |     | 1 |     |      |
| Statements of Net Assets Available for Benefits                                   |     | 2 |     |      |
| Statements of Changes in Net Assets Available for Benefits                        |     | 3 |     |      |
| Notes to Financial Statements                                                     |     | 4 |     |      |
| Schedule H, line 4i - Schedule of Assets (Held at End of Year), December 31, 2024 |     | 9 |     |      |

<div align='center'>1</div>

### ASSOCIATED BANC-CORP

#### 401(k) & EMPLOYEE STOCK OWNERSHIP PLAN
<div align='center'>Statements of Net Assets Available for Benefits