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( Mark One ) UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10 - K ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31 , 2020 TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Wisconsin ( State or other jurisdiction of incorporation or organization ) 433 Main Street Green Bay , Wisconsin ( Address of principal executive offices ) Commission file number : 001-31343 ASSOCIATED BANC - CORP ( 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 : Trading symbol ASB ASB PrC ASB PrD ASB PRE ASB PrF 39-1098068 ( I.R.S. Employer Identification No. ) Title of each class Common stock , par value $ 0.01 per share Depositary Shrs , each representing 1 / 40th intrst in a shr of 6.125 % Non - Cum . Perp Pref Stock , Srs C Depositary Shrs , each representing 1 / 40th intrst in a shr of 5.375 % Non - Cum . Perp Pref Stock , Srs D Depositary Shrs , each representing 1 / 40th intrst in a shr of 5.875 % Non - Cum . Perp Pref Stock , Srs E Depositary Shrs , each representing 1 / 40th intrst in a shr of 5.625 % Non - Cum . Perp Pref Stock , Srs F 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 . Yes p No Large accelerated filer Non - accelerated filer Emerging growth company 54301 ( Zip Code ) Name of each exchange on which registered The New York Stock Exchange The New York Stock Exchange The New York Stock Exchange The New York Stock Exchange The New York Stock Exchange 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 p 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 . Yes p No " 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 ) . Yes p No " Indicate by check mark whe the registrant is a large accelerated filer , an accelerated filer , a non - accelerated filer , a maller reporting company or 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 . Accelerated filer Smaller reporting 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 . 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 . Yes p No Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Act ) . Yes ☐ No p As of June 30 , 2020 , ( 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 $ 2,058,439,343 . This excludes $ 43,022,845 of market value representing the outstanding shares of the registrant owned by all directors and officers who may be deemed affiliates . This includes $ 37,269,751 of market value representing 1.77 % of the outstanding shares of the registrant held in a fiduciary capacity by the trust company subsidiary of the registrant . As of February 5 , 2021 , 152,831,898 shares of common stock were outstanding . DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant's Proxy Statement for the Annual Meeting of Shareholders to held on April 27 , 2021 are incorporated by reference in this Form 10 - K into Part III .