Company: ASB
Filing Date: 2025-12-30
Form Type: S-4
Source: 0001193125-25-337086
Chunk: 0

Company: ASSOCIATED BANC-CORP
Filing Date: 2025-12-30
Form: S-4
Chunk 0
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As filed with the Securities and Exchange Commission on December 30, 2025 Registration No. 333- SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-4 REGISTRATION STATEMENT Under THE SECURITIES ACT OF 1933 ASSOCIATED BANC-CORP (Exact Name of Registrant as specified in its charter)

| Wisconsin                       |     |                         6021 |     | 39-1098068            |
| (State or other jurisdiction of 
 incorporation or organization)  |     | -Primary Standard Industrial 
   Classification Code Number |     | -I.R.S. Employer      
 Identification Number |

433 Main Street Green Bay, Wisconsin 54301 (920) 491-7500 (Address, including zip code, and telephone number, including area code, of Registrant’s principal executive offices) Randall J. Erickson Executive Vice President, General Counsel and Corporate Secretary Associated Banc-Corp 433 Main Street Green Bay, Wisconsin 54301 (920) 491-7500 (Name, address, including zip code, and telephone number, including area code, of agent for service) Copies to:

| Edward D. Herlihy                        
 Nicholas G. Demmo Wachtell,              
 Lipton, Rosen & Katz 51 West 52nd Street 
 New York, New York 10019                 
 (212) 403-1000                           |     | John F. Kotouc                                   
 Dianne S. Lozier Co-Chief                        
 Executive Officers American National Corporation 
 8990 West Dodge Road Omaha,                      
 Nebraska 68114 (800) 279-0007                    |     | Mark C. Kanaly                     
 Alston & Bird LLP                  
 2200 Ross Avenue, Suite 2300       
 Dallas, Texas 75201 (214) 922-3400 |

Approximate date of commencement of proposed sale of the securities to the public:As soon as practicable after this Registration Statement is declared effective and upon completion of the Merger described herein. If the securities being registered on this Form are being offered in connection with the formation of a holding company and there is compliance with General Instruction G, check the following box. ☐ If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐ If this Form is a post-effective amendment filed pursuant to