ASSOCIATED BANC-CORP

“

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

(Mark One)

Commission file number:001-31343

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (920)491-7500

SECURITIES REGISTERED PURSUANT TO SECTION 12(b) OF THE ACT:

SECURITIES REGISTERED PURSUANT TO SECTION 12(g) OF THE ACT:

None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.

Yes¨ No þ

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

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.¨

Indicate by check mark whether the registrant has filed a report on and attestation to its management's assessment of the effectiveness of its internal controls over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. þ

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements.¨

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant's executive officers during the relevant recovery period pursuant to §240.10D-1(b).¨

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act).

Yes ☐ Noþ

As of June 30, 2025, (the last business day of the registrant’s most recently completed second fiscal quarter) the aggregate market value of the voting stock held by nonaffiliates of the registrant was $3,998,795,954. This excludes $44,543,831 of market value representing the outstanding shares of the registrant owned by all directors and officers who may be deemed affiliates. This includes $61,551,067 of market value representing 1.52% of the outstanding shares of the registrant held in a fiduciary capacity by the trust company subsidiary of the registrant.

As of January 30, 2026,165,975,086 shares of common stock were outstanding.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the registrant's Proxy Statement for the Annual Meeting of Shareholders to be held on April 28, 2026 are incorporated by reference in this Form 10-K into Part III.

Auditor Name: KPMG LLP Auditor Location: Chicago, Illinois Auditor Firm ID:185

2025 Form 10-K Table of Contents

ASSOCIATED BANC-CORP

Commonly Used Terms

The following listing provides a reference of common acronyms, abbreviations, and other defined terms used throughout the document:

Special Note Regarding Forward-Looking Statements

This document, including the documents that are incorporated by reference, contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended and Section 21E of the Exchange Act. You can identify forward-looking statements by words such as "believe," "expect," "anticipate," "plan," "estimate," "should," "intend," "target," "outlook," "project," "guidance," "forecast," or similar expressions. You should read statements that contain these words carefully because they discuss our future expectations or state other "forward-looking" information. Such forward-looking statements may relate to our financial condition, results of operations, plans, objectives, future performance, or business and are based upon the beliefs and assumptions of our management and the information available to our management at the time these disclosures are prepared. These forward-looking statements involve risks and uncertainties that we may not be able to accurately predict or control and our actual results may differ materially from those we described in our forward-looking statements. Shareholders should be aware that the occurrence of the events discussed under the heading Risk Factors in this document, and in the information incorporated by reference herein, could have an adverse effect on our business, results of operations, and financial condition. These factors, many of which are beyond our control, include the following.

•Credit risks, including changes in economic conditions and risk relating to our ACL.

•Liquidity and interest rate risks, including the impact of capital market conditions and changes in monetary policy on our borrowings and net interest income.

•Operational risks, including processing, information systems, cybersecurity, vendor problems, business interruption, and fraud risks.

•Strategic and external risks, including economic, political, and competitive forces impacting our business.

•Risk relating to Associated's previously announced proposed acquisition of American National, including delays in or failure to complete the proposed transaction, or to realize its anticipated net benefits.

•Legal, compliance, and reputational risks, including regulatory and litigation risks.

•The risk that our analyses of these risks and forces could be incorrect and/or that the strategies developed to address them could be unsuccessful.

For a discussion of these and other risks that may cause actual results to differ from expectations, please refer to the Risk Factors Summary and Risk Factors sections of this document. The forward-looking statements contained or incorporated by reference in this document relate only to circumstances as of the date on which the statements are made. We undertake no obligation to update or revise any forward-looking statements, whether as a result of new information, future events, or otherwise.

Risk Factors Summary

Our business is subject to a number of risks, a summary of which is set forth below. These risks are discussed more fully in Part I, Item 1A, Risk Factors herein.

Credit Risks

Liquidity and Interest Rate Risks

Operational Risks

Strategic and External Risks

Legal, Regulatory, Compliance and Reputational Risks

Risks Related to an Investment in Our Securities

General Risk Factors