Company: ASB
Filing Date: 2025-03-19
Form Type: DEFA14A
Source: 0001104659-25-025447
Chunk: 0

Company: ASSOCIATED BANC-CORP
Filing Date: 2025-03-19
Form: DEFA14A
Chunk 0
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<div align='center'>UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section
14(a) of the Securities Exchange Act of 1934

(Amendment No. )</div>

Filed by the Registrant x

Filed by a Party other than the Registrant ¨

Check the appropriate box:

| ¨ | Preliminary Proxy Statement                      |
| ¨ | Confidential, for Use of the Commission Only (as 
 permitted by Rule 14a-6(e)(2))                   |
| ¨ | Definitive Proxy Statement                       |
| x | Definitive Additional Materials                  |
| ¨ | Soliciting Material Pursuant to §240.14a-12      |

| ASSOCIATED                                                              
 BANC-CORP                                                               |
| (Name of Registrant as Specified in its Charter)                        |
| (Name of Person(s) Filing Proxy Statement if other than the Registrant) |

Payment of Filing Fee (Check all boxes that apply):

| x | No fee required                                   |
| ¨ | Fee paid previously with preliminary materials    |
| ¨ | Fee computed on table in exhibit required by Item 
 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11 |

<div align='center'>ASSOCIATED BANC-CORP

Supplement No. 1 to

Proxy Statement dated March 17, 2025</div>

This Supplement No. 1 to the Proxy Statement
of Associated Banc-Corp (the “Company”), filed on Schedule 14A with the Securities and Exchange Commission on March 17,
2025 (the “Proxy Statement”) in connection with the Annual Meeting of Shareholders to be held on April 29, 2025, is being
filed solely for the purpose of correcting (i) the ages of Ms. Eileen A. Kamerick and Messrs. Gale E. Klappa and Owen J.
Sullivan in the Proxy Statement, each of whom is an incumbent director of the Company and a nominee for director in the Proxy Statement,
and (ii) the disclosure regarding the treatment and effect of abstentions and broker non-votes with respect to the proposals presented
in the Proxy Statement.

The ages listed on pages 6 through 8 of the
Proxy Statement for Ms. Eileen A. Kamerick and Messrs. Gale E