ASSOCIATED BANC-CORP

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 OR 15(d) of the Securities Exchange Act of 1934

Associated Banc-Corp

(Exact name of registrant as specified in its charter)

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company¨

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.¨

On November 18, 2024, Associated Banc-Corp (the “Company”) completed its underwritten public offering of 13,800,000 shares of the Company’s common stock, $0.01 par value per share (the “Common Stock”) pursuant to the Company’s Registration Statement on Form S-3 (File No. 333-280004) and a related prospectus, including the related preliminary and final prospectus supplements dated November 14, 2024, filed with the Securities and Exchange Commission. The Company entered into an underwriting agreement (the “Underwriting Agreement”) with BofA Securities, Inc. and J.P. Morgan Securities LLC (the “Underwriters”), pursuant to which the Company issued and sold the shares of Common Stock to the Underwriters at a price to the public of $25.00 per share. The Underwriting Agreement includes customary representations, warranties and covenants by the Company. The Company also agreed to indemnify the underwriters against certain liabilities under the Securities Act of 1933, as amended. The Company granted the Underwriters an option to purchase up to 1,800,000 additional shares of Common Stock on the same terms and conditions for 30 days after the date of the prospectus, which the Underwriters exercised in full on November 15, 2024. The net proceeds to the Company from the offering are expected to be approximately $330.7 million, after deducting underwriting discounts and commissions and estimated offering expenses payable by the Company.

The foregoing description of the Underwriting Agreement is qualified in its entirety by reference to the Underwriting Agreement, a copy of which is attached hereto as Exhibit 1.1 and incorporated herein by reference. The legal opinion relating to the shares of Common Stock issued in the offering is attached hereto as Exhibit 5.1.

(d) Exhibits

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.