Associated Banc-Corp (ASB) 424B3Prospectus supplement

The impact of any one of the factors above, such as an increase in United States interest rates, may offset some or all of any change in the market value of the notes attributable to another factor.

The credit ratings assigned to the notes may not reflect the potential impact of all risks related to structure and other factors on any trading market for, or trading value of, your notes. In addition, real or anticipated changes in our credit ratings will generally affect the trading market for, or the trading value of,

The FRBNY began to publish SOFR in April 2018. Although the FRBNY has also begun publishing historical indicative SOFR going back to 2014, such historical indicative data inherently involves assumptions, estimates and approximations. Therefore, SOFR has limited performance history and no actual investment based on the performance of SOFR was possible before April 2018. The level of SOFR during the floating rate period for the notes may bear little or no relation to the historical level of SOFR. The future performance of SOFR is impossible to predict and, therefore, no future performance of SOFR or the notes may be inferred from any of the hypothetical or actual historical performance data. Hypothetical or actual historical performance data are not indicative of the future performance of SOFR or the notes. Changes in the levels of SOFR will affect Compounded SOFR and, therefore, the return on the notes and the trading price of such notes, but it is impossible to predict whether such levels will rise or fall. There can be no assurance that SOFR or Compounded SOFR will be positive.

The notes initially will be limited to an aggregate principal amount of $      . We may, from time to time, without notice to or consent of the existing holders of the notes, issue additional notes under the indenture having the same terms as the notes in all respects, except for the issue price, the issue date, and, in some cases, the initial interest accrual date and the initial interest payment date. Any such additional notes, together with the notes being issued hereby, will constitute a single series under the indenture; provided, however, that no additional notes may be issued unless they will be fungible with the notes offered hereby for United States federal income tax and securities law purposes and have the same CUSIP number as the notes offered hereby. The notes are not convertible into or exchangeable for shares of our common stock, our preferred stock or any other securities.

The notes will be our unsecured and unsubordinated obligations, and will rank equally in right of payment with all of our other unsubordinated debt from time to time outstanding. The notes will be effectively subordinated to any secured debt of ours to the extent of the value of the collateral securing such indebtedness. As of June 30, 2024, we had no outstanding secured indebtedness. The notes will not be guaranteed by any of our subsidiaries.

We are a bank holding company that conducts substantially all of our operations through subsidiaries. As a result, claims of the holders of the notes will be structurally subordinated in right of payment to claims of creditors of our subsidiaries, except to the extent that we may be recognized, and receive payment, as a creditor of those subsidiaries. Claims of our subsidiaries’ creditors, other than Associated Banc-Corp, include substantial amounts of long-term debt, deposit liabilities, federal funds purchased, securities sold under repurchase agreements, commercial paper and other short-term borrowings. As of June 30, 2024, our subsidiaries had, in the aggregate, outstanding debt and other liabilities, including deposits, of approximately $36.2 billion (excluding intercompany liabilities). All of such debt and other liabilities would rank structurally senior to the notes in case of liquidation or otherwise.

We may, from time to time, without notice or consent from the holders of the notes, incur additional indebtedness that ranks equally or subordinate in right of payment to the notes.

The notes are not deposits or other obligations of a bank or savings association and are not insured or guaranteed by the FDIC or any other governmental agency.

The notes will be issued in registered book-entry form without coupons in denominations of $2,000 and integral multiples of $1,000 in excess thereof.

For the floating rate period, interest will be computed on the basis of the actual number of days in each interest period (or any other relevant period) and a 360-day year. The amount of accrued interest payable on the notes for each interest period during the floating rate period will be computed by multiplying (i) the outstanding principal amount of the notes by (ii) the product of (a) the interest rate for the relevant interest period multiplied by (b) the quotient of the actual number of days in the applicable interest period divided by 360. The interest rate on the notes will in no event be higher than the maximum rate permitted by New York law as the same may be modified by United States law of general application and will in no event be lower than zero. For the floating rate period, if any floating interest payment date of the notes (other than the maturity date or any redemption date) falls on a day which is not a business day, that floating interest payment date will be postponed and the related payment of interest on the notes will be made on the next day which is a business day, except that if the next succeeding business day falls in the next calendar month, then such floating interest payment date will be advanced to the immediately preceding day that is a business day, and in each case, the related interest periods will also be adjusted for such non-business days.

The Calculation Agent will determine Compounded SOFR, the interest rate and accrued interest for each interest period in the floating rate period in arrears as soon as reasonably practicable on or after the Interest Payment Determination Date (as defined below) for such interest period and prior to the relevant floating interest payment date and will notify us (if we are not the Calculation Agent) of Compounded SOFR, such interest rate and accrued interest for each interest period in the floating rate period as soon as reasonably practicable after such determination, but in any event by the business day immediately prior to

SOFR is published by the FRBNY and is intended to be a broad measure of the cost of borrowing cash overnight collateralized by U.S. Treasury securities. The FRBNY reports that SOFR includes all trades in the Broad General Collateral Rate and bilateral Treasury repurchase agreement (repo) transactions cleared through the delivery-versus-payment service offered by the Fixed Income Clearing Corporation, a subsidiary of The Depository Trust and Clearing Corporation (“DTCC”), and SOFR is filtered by the FRBNY to remove some (but not all) of the foregoing transactions considered to be “specials.” According to the FRBNY, “specials” are repos for specific-issue collateral, which take place at cash-lending rates below those for general collateral repos because cash providers are willing to accept a lesser return on their cash in order to obtain a particular security.

The SOFR Index is published by the FRBNY and measures the cumulative impact of compounding SOFR on a unit of investment over time, with the initial value set to 1.00000000 on April 2, 2018, the first value date of SOFR. The SOFR Index value reflects the effect of compounding SOFR each business day and allows the calculation of compounded SOFR averages over custom time periods.

The FRBNY notes on its publication page for the SOFR Index that use of the SOFR Index is subject to important limitations, indemnification obligations and disclaimers, including that the FRBNY may alter the methods of calculation, publication schedule, rate revision practices or availability of the SOFR Index at any time without notice. The interest rate for any interest period during the floating rate period will not be adjusted for any modifications or amendments to the SOFR Index or SOFR data that the FRBNY may publish after the interest rate for that interest period has been determined.

Because SOFR is published by the FRBNY based on data received from other sources, we have no control over its determination, calculation or publication. The information regarding SOFR contained in this section is based upon the New York Federal Reserve’s Website and other U.S. government sources.

plus, in either case, accrued and unpaid interest thereon, if any, to, but excluding, the redemption date.

Our actions and determinations in determining the redemption price shall be conclusive and binding for all purposes, absent manifest error.

If we redeem the notes at our option, notwithstanding the foregoing, installments of interest on the notes that are due and payable on any interest payment date falling on or prior to a redemption date for the notes will be payable on that interest payment date to the registered holders thereof as of the close of business on the relevant record date according to the terms of the notes and the indenture.

The notes are not subject to any sinking fund. The notes are not mandatorily redeemable at the option of the holders.

Notice of any redemption will be mailed or electronically delivered (or otherwise transmitted in accordance with the depositary’s procedures) at least 10 days but not more than 60 days before the redemption date to each holder of notes to be redeemed.

In the case of a partial redemption, selection of the notes for redemption will be made by the trustee by lot. No notes of a principal amount of $2,000 or less will be redeemed in part. If any note is to be redeemed in part only, the notice of redemption that relates to the note will state the portion of the principal amount of the note to be redeemed. A new note in a principal amount equal to the unredeemed portion of the note will be issued in the name of the holder of the note upon surrender for cancellation of the original note. For so long as the notes are held by DTC (or another depositary), the redemption of the notes shall be done in accordance with the policies and procedures of the depositary.

Unless we default in payment of the redemption price, on and after the redemption date interest will cease to accrue on the notes or portions thereof called for redemption.

default in the payment of interest on any note and the continuance of that default for 30 days;

If any event of default with respect to the notes occurs and is continuing, either the trustee or the holders of not less than 25% in principal amount of the outstanding notes may declare the principal amount of the notes to be due and payable immediately. No such declaration is required upon specified events of bankruptcy, insolvency or reorganization. Subject to certain conditions, the holders of a majority in principal amount of the outstanding notes may rescind and annul the declaration.

If we exercise our covenant defeasance option with respect to the notes, then even if there were a default under the related covenant, payment of the notes could not be accelerated. We may exercise our defeasance option with respect to the notes even if we previously had exercised our covenant defeasance option. If we exercise our defeasance option, payment of the notes may not be accelerated because of any event of default. If we exercise our covenant defeasance option and acceleration were to occur, the realizable value at the acceleration date of the money and U.S. government obligations in the defeasance trust could be less than the principal and interest then due on the notes. This is because the required deposit of money and/or U.S. government obligations in the defeasance trust is based upon scheduled cash flows rather than market value, which will vary depending upon interest rates and other factors.

The indenture provides that we, together with the trustee, may enter into supplemental indentures without the consent of any holders of the notes to, among other things:

Other amendments and modifications of the indenture may be made with the consent of the holders of not less than a majority of the aggregate principal amount of outstanding notes of each series affected by such amendments or modifications. No modification or amendment may, however, without the consent of each holder of outstanding notes of each series affected by such amendment or modification:

The indenture provides that in determining whether the holders of the requisite principal amount of the outstanding notes have given, made or taken any request, demand, authorization, direction, notice, consent or waiver under the indenture, notes owned by Associated Banc-Corp or any affiliate of Associated Banc-Corp shall be disregarded and deemed not to be outstanding.

We may, without the consent of the holders of the notes, consolidate or merge with any other person or transfer or lease our properties and assets substantially as an entirety to another person or permit another person to consolidate with or merge into Associated Banc-Corp, as long as:

The indenture contains a covenant that provides, so long as any of the notes are outstanding, that neither we nor any of our subsidiaries will sell, grant a security interest in or otherwise dispose of any shares (or any securities convertible into, or options, warrants or rights to purchase, shares) of voting stock (other than directors’ qualifying shares) of any principal subsidiary bank, except to us or any intermediate subsidiary. In addition, the covenant provides that neither we nor any intermediate subsidiary will permit any principal subsidiary bank to issue any shares (or securities convertible into, or options, warrants or rights to purchase, shares) of its voting stock (other than directors’ qualifying shares), except to us or any intermediate subsidiary. We further will not permit any intermediate subsidiary that owns any shares (or any securities convertible into, or options, warrants or rights to purchase, shares) of voting stock of any principal subsidiary bank to cease to be an intermediate subsidiary.

The above covenant is subject to our rights in connection with a consolidation or merger of us with or into another person or a sale of our assets substantially as an entirety. The covenant also does not apply if:

The above covenant also does not restrict our principal bank subsidiary from being consolidated with or merged into another domestic banking institution, if after the merger or consolidation (A) we and any one or more intermediate subsidiaries collectively own at least 80% of the voting stock of the resulting banking institution and (B) no event of default, and no event which, after notice or lapse of time or both, would become an event of default under the indenture shall have happened and be continuing.

Upon the sale, exchange or other taxable disposition of a note, a U.S. Holder will generally recognize taxable gain or loss equal to the difference, if any, between (i) the sum of all cash plus the fair market value of all other property received on such disposition (except to the extent such cash or other property is attributable to accrued but unpaid interest, which is treated as interest as discussed under “United States Federal Income Taxation of U.S. Holders — Payments of stated interest”) and (ii) such holder’s adjusted tax basis in the note. A U.S. Holder’s adjusted tax basis in a note generally will equal the cost of the note to such holder. Any gain or loss recognized on the disposition of a note generally will be capital gain or loss, and will be long-term capital gain or loss if, at the time of such disposition, the U.S. Holder’s holding period for the note is more than one year. Long-term capital gain of non-corporate U.S. Holders is generally taxed at preferential rates. The deductibility of capital loss by a U.S. Holder is subject to limitations.

For each calendar year in which the notes are outstanding, we generally are required to provide the IRS with certain information, including the beneficial owner’s name, address and taxpayer identification number, the aggregate amount of interest paid to that beneficial owner during the calendar year and the amount of tax withheld, if any. This obligation, however, does not apply with respect to payments to certain types of U.S. Holders, including corporations and tax-exempt organizations, provided that they establish entitlement to an exemption.

In the event that a U.S. Holder subject to the reporting requirements described above fails to provide its correct taxpayer identification number in the manner required by applicable law, fails to certify that it is exempt from backup withholding, or underreports its tax liability, we, our agent or paying agents, or a broker may be required to “backup” withhold a tax at the rate set forth in the Code (currently 24%) from each payment on the notes and on the proceeds from a sale of the notes.

Backup withholding is not an additional tax and may generally be refunded or credited against the U.S. Holder’s United States federal income tax liability, provided that the required procedures are followed, and the required information is timely furnished to the IRS.

U.S. Holders should consult their own tax advisors regarding their qualifications for an exemption from backup withholding, and the procedure for establishing such exemption, if applicable.

In addition to the United States federal income tax, certain individuals, estates and trusts may be required to pay a 3.8% Medicare surtax on the lesser of their (i) “net investment income” ​(or “undistributed net investment income” in the case of an estate or trust) including, among other things, interest and net gain sale in respect of securities like the notes, subject to certain exceptions, or (ii) the amount by which the taxpayer’s adjusted gross income exceeds a certain threshold ($250,000 for married individuals filing jointly, $200,000 for unmarried individuals and $125,000 for married individuals filing separately).

Subject to the discussion below of backup withholding and FATCA (as defined below), payments of interest on the notes to a Non-U.S. Holder will generally not be subject to United States federal withholding tax under the “portfolio interest exemption,” provided that:

If a Non-U.S. Holder cannot satisfy the requirements of the “portfolio interest exemption,” payments of stated interest made to such Non-U.S. Holder will be subject to United States federal withholding tax at a rate of 30% unless the beneficial owner of the note provides the applicable withholding agent with a properly executed:

Non-U.S. Holders should consult their own tax advisors about the specific methods for satisfying these requirements. A claim for exemption will not be valid if the person receiving the applicable form has actual knowledge or reason to know that the statements on the form are false.

If interest on the notes is effectively connected with a United States trade or business of the beneficial owner (and, if required by an applicable income tax treaty, attributable to a United States permanent establishment or fixed base), the Non-U.S. Holder, although exempt from the withholding tax described above, will be subject to United States federal income tax on such interest on a net income basis in the same manner as if it were a U.S. Holder. In addition, if such Non-U.S. Holder is a foreign corporation, it may be subject to a branch profits tax at a rate of 30% (unless reduced by an applicable income tax treaty) in respect of such interest.

Except with respect to accrued and unpaid interest, a Non-U.S. Holder will not be subject to United States Federal Income Tax on gain or income realized on the sale, exchange or other disposition of a note unless (a) the Non-U.S. Holder is an individual who is present in the United States for a period or periods aggregating 183 or more days in the taxable year of the disposition and certain other conditions are met, or (b) such gain or income is effectively connected with a United States trade or business (and, if required by an applicable income tax treaty, attributable to a United States permanent establishment or fixed base). Accrued and unpaid interest realized on a sale, exchange or other disposition of a note will be treated as discussed under “— United States federal income taxation of Non-U.S. Holders — Payments of stated interest.”

A Non-U.S. Holder described in (a) above will be subject to United States federal income tax at a rate of 30% (unless a lower rate applies under an applicable income tax treaty) on the gain derived from the sale, exchange or other disposition, which may be offset by United States source capital loss, even though the

We and the underwriters for the offering named below have entered into an underwriting agreement with respect to the notes. Subject to certain conditions, each underwriter has severally agreed to purchase the principal amount of the notes indicated in the following table.

The notes sold by the underwriters to the public will initially be offered at the initial public offering prices set forth on the cover of this prospectus supplement. Any notes sold by the underwriters to securities dealers may be sold at a discount from the initial public offering price of up to    % of the principal amount of the notes. Any such securities dealers may resell any notes purchased from the underwriters to certain other brokers or dealers at a discount from the initial public offering price of up to    % of the principal amount of the notes. After the initial offering, the underwriters may change the offering price and the other selling terms. The offering of the notes by the underwriters is subject to receipt and acceptance and subject to the underwriters’ right to reject any order in whole or in part.

The notes are a new issue of securities with no established trading market. The company has been advised by the underwriters that the underwriters intend to make a market in the notes but are not obligated to do so and may discontinue market making at any time without notice. No assurance can be given as to the liquidity of the trading market for the notes.

The underwriters expect to deliver the notes to purchasers in book entry form only through the facilities of DTC, and its participants, including Euroclear and Clearstream, on or about            , 2024, which is the   business day following the pricing of the notes (“T+    ”). Under Rule 15c6-1 of the Exchange Act, trades in the secondary market generally are required to settle in one business day, unless the parties to a trade expressly agree otherwise. Accordingly, purchasers who wish to trade notes more than one business day prior to the settlement date will be required, by virtue of the fact that the notes initially will settle in T+    , to specify alternative settlement arrangements to prevent a failed settlement.

These transactions may include short sales, stabilizing transactions and purchases to cover positions created by short sales. Short sales involve the sale by the underwriters of a greater number of notes than they are required to purchase in the offering. Stabilizing transactions consist of certain bids or purchases made for the purpose of preventing or retarding a decline in the market price of the notes while the offering is in progress.

The underwriters also may impose a penalty bid. This occurs when a particular underwriter repays to the underwriters a portion of the underwriting discount received by it because the representatives have repurchased notes sold by or for the account of such underwriter in stabilizing or short covering transactions.

These activities by the underwriters may stabilize, maintain or otherwise affect the market price of the notes. As a result, the price of the notes may be higher than the price that otherwise might exist in the open market. If these activities are commenced, they may be discontinued by the underwriters at any time.

We estimate that our share of the total expenses of the offering, excluding the underwriting discount, will be approximately $      .

We have agreed to indemnify the several underwriters against certain liabilities, including liabilities under the Securities Act of 1933.

We have agreed for a period from the date of this prospectus supplement through and including the business day following the closing date of this offering, that we will not, without the prior written consent of the underwriters, offer, sell, contract to sell or otherwise dispose of any debt securities issued or guaranteed by us and having a tenor of more than one year.

The underwriters and affiliates are full-service financial institutions engaged in various activities, which may include sales and trading, commercial and investment banking, advisory, investment management, investment research, principal investment, hedging, market making, brokerage and other financial and non-financial activities and services. Certain of the underwriters and their affiliates have provided, and may in the future provide, a variety of these services to us and to persons and entities with relationships with us, for which they received or will receive customary fees and expenses.

In addition, in the ordinary course of their business activities, the underwriters and their affiliates may make or hold a broad array of investments and actively trade debt and equity securities (or related derivative securities) and financial instruments (including bank loans) for their own account and for the accounts of their customers. Such investments and securities activities may involve securities and/or instruments of ours or our affiliates. Certain of the underwriters or their affiliates that have a lending relationship with us routinely hedge, and certain other of those underwriters or their affiliates may hedge, their credit exposure to us consistent with their customary risk management policies. Typically, such underwriters and their affiliates would hedge such exposure by entering into transactions which consist of either the purchase of credit default swaps or the creation of short positions in our securities, including potentially the notes offered hereby. Any such credit default swaps or short positions could adversely affect future trading prices of the notes offered hereby. The underwriters and their affiliates may also make investment recommendations and/or publish or express independent research views in respect of such securities or financial instruments and may hold, or recommend to clients that they acquire, long and/or short positions in such securities and instruments.

The notes may be sold only to purchasers purchasing, or deemed to be purchasing, as principal, that are accredited investors, as defined in National Instrument 45-106 Prospectus Exemptions or subsection 73.3(1) of the Securities Act (Ontario), and are permitted clients, as defined in National Instrument 31-103 Registration Requirements, Exemptions and Ongoing Registrant Obligations. Any resale of the notes must be made in accordance with an exemption from, or in a transaction not subject to, the prospectus requirements of applicable securities laws.

Securities legislation in certain provinces or territories of Canada may provide a purchaser with remedies for rescission or damages if this prospectus supplement or the accompanying base prospectus (including any amendment thereto) contain a misrepresentation, provided that the remedies for rescission or damages are exercised by the purchaser within the time limit prescribed by the securities legislation of the purchaser’s province or territory. The purchaser should refer to any applicable provisions of the securities legislation of the purchaser’s province or territory for particulars of these rights or consult with a legal advisor.

Pursuant to section 3A.3 of National Instrument 33-105 Underwriting Conflicts (“NI 33-105”), the Underwriters are not required to comply with the disclosure requirements of NI 33-105 regarding underwriter conflicts of interest in connection with this offering. Upon receipt of this prospectus supplement or the accompanying base prospectus, each Canadian investor hereby confirms that it has expressly requested that all documents evidencing or relating in any way to the sale of the securities described herein (including for greater certainty any purchase confirmation or any notice) be drawn up in the English language only.

We are a bank holding company registered pursuant to the Bank Holding Company Act of 1956, as amended. Our bank subsidiary, Associated Bank, traces its history back to the founding of the Bank of Neenah in 1861. We were incorporated in Wisconsin in 1964 and were inactive until 1969 when permission was received from the Federal Reserve System to acquire three banks. At March 31, 2024, we owned one nationally chartered commercial bank headquartered in Green Bay, Wisconsin, which serves local communities across the upper Midwest, one nationally chartered trust company headquartered in Milwaukee, Wisconsin, and 12 limited purpose banking and nonbanking subsidiaries either located in or conducting business primarily in our three state branch footprint (Wisconsin, Illinois, and Minnesota) that are closely related or incidental to the business of banking or financial in nature. Measured by total assets reported at March 31, 2024, we are the largest bank holding company headquartered in Wisconsin.

Through Associated Bank and various nonbanking subsidiaries, we provide a broad array of banking and nonbanking products and services to individuals and businesses through 188 banking branches at March 31, 2024, serving more than 100 communities, primarily within our three-state branch footprint. Our business is primarily relationship-driven and is organized into three reportable segments: Corporate and Commercial Specialty; Community, Consumer, and Business; and Risk Management and Shared Services.

We may issue the debt securities in one or more separate series of senior debt securities and/or subordinated debt securities. We will specify in the prospectus supplement relating to a particular series of debt securities being offered the particular amounts, prices, and terms of those debt securities. These terms may include:

Where appropriate, the applicable prospectus supplement will describe the U.S. federal income tax considerations relevant to the debt securities.

Some of the debt securities may be issued as original issue discount securities. Original issue discount securities bear no interest or bear interest at below-market rates and will be sold at a discount below their stated principal amount. Any applicable prospectus supplement will also contain any special U.S. federal income tax or other information relating to original issue discount securities.

Persons considering the purchase, ownership, or disposition of original issue discount debt securities or other kinds of debt securities, including debt securities linked to an index or payable in currencies other than U.S. dollars, should consult their own tax advisors concerning the U.S. federal income tax consequences to them from the purchase, ownership, or disposition of those securities in light of their particular situations, as well as any consequences arising under the laws of any other taxing jurisdiction.

Unless otherwise specified in the applicable prospectus supplement, we will issue the senior and subordinated debt securities only in fully registered form without coupons. You will not be required to pay a

The senior indenture defines the term “principal subsidiary bank” to mean any of our subsidiaries which is a commercial bank and which has total assets equal to 30 percent or more of the total consolidated assets of Associated Banc-Corp as of the date of our most recent audited consolidated financial statements. At present, Associated Bank, National Association is our sole subsidiary bank which constitutes a principal subsidiary bank under this definition. As used above, “voting stock” means a class of stock having general voting power under ordinary circumstances irrespective of the happening of a contingency. The above covenant would not prevent our principal subsidiary bank from engaging in a sale of assets to the extent otherwise permitted by the senior indenture.

If any event of default with respect to senior debt securities of any series occurs and is continuing, either the trustee or the holders of not less than 25% in principal amount of the outstanding senior debt securities of that series may declare the principal amount (or, if the senior debt securities of that series are original issue discount senior debt securities, a specified portion of the principal amount) of all senior debt securities of that series to be due and payable immediately. No such declaration is required upon specified events of bankruptcy, insolvency or reorganization. Subject to certain conditions, the holders of a majority in principal amount of the outstanding senior debt securities of that series may annul the declaration.

We will describe in the applicable prospectus supplement any particular provisions relating to the acceleration of the maturity of a portion of the principal amount of original issue discount senior debt securities upon an event of default.

Subject to the duty to act with the required standard of care during a default, the trustee is not obligated to exercise any of its rights or powers under the senior indenture at the request or direction of any of the holders of senior debt securities, unless the holders have offered to the trustee security or indemnity reasonably satisfactory to the trustee. The senior indenture provides that the holders of a majority in principal amount of outstanding senior debt securities of any series may direct the time, method, and place of conducting any proceeding for any remedy available to the trustee for that series, or exercising any trust or other power conferred on the trustee. However, the trustee may decline to act if the direction is contrary to law or the senior indenture.

The senior indenture includes a covenant requiring us to file annually with the trustee a certificate of no default or specifying any default that exists.

To make either of the above elections, we must deposit in trust with the trustee money and/or U.S. government obligations (as defined below) or, with respect to senior debt securities denominated in a foreign currency, foreign government obligations (as defined below) which, through the payment of principal and interest in accordance with their terms, will provide sufficient money, without reinvestment, to repay in full those senior debt securities.

As used in the senior indenture, “foreign government obligations” are direct obligations of a foreign government or governments or of an agency or instrumentality of such foreign government or governments, in either case that is guaranteed as a full faith and credit obligation of such foreign government or governments and that is not callable or redeemable by the issuer.

As a condition to defeasance or covenant defeasance, we must deliver to the trustee an opinion of counsel that the holders of the senior debt securities will not recognize income, gain, or loss for federal income tax purposes as a result of the defeasance or covenant defeasance and will be subject to federal income tax on the same amount, in the same manner and at the same times as would have been the case if defeasance or covenant defeasance had not occurred. That opinion, in the case of defeasance, but not covenant defeasance, must refer to and be based upon a ruling received by us from the Internal Revenue Service or published as a revenue ruling or upon a change in applicable federal income tax law.

If we exercise our covenant defeasance option with respect to a particular series of senior debt securities, then even if there were a default under the related covenant, payment of those senior debt securities could not be accelerated. We may exercise our defeasance option with respect to a particular series of senior debt securities, even if we previously had exercised our covenant defeasance option. If we exercise our defeasance option, payment of those senior debt securities may not be accelerated because of any event of default. If we exercise our covenant defeasance option and acceleration were to occur, the realizable value at the acceleration date of the money and U.S. government obligations in the defeasance trust could be less than the principal and interest then due on those senior debt securities. This is because the required deposit of money and/or U.S. government obligations in the defeasance trust is based upon scheduled cash flows rather than market value, which will vary depending upon interest rates and other factors.

The holders of subordinated debt securities of a series that are specified to be convertible into our common stock or other securities will be entitled as specified in the applicable prospectus supplement to convert those convertible subordinated debt securities into common stock or such other securities, at the conversion price, at the times, and on the terms set forth in the prospectus supplement.

As used in this prospectus, “senior indebtedness” means (1) the principal of (and premium, if any) and interest in respect of indebtedness of the Company for purchased or borrowed money, whether or not evidenced by securities, notes, debentures, bonds or other similar instruments issued by the Company; (2) all capital lease obligations of the Company; (3) all obligations of the Company issued or assumed as the deferred purchase price of property, all conditional sale obligations of the Company and all obligations of the Company under any conditional sale or title retention agreement, but excluding trade accounts payable in the ordinary course of business; (4) all obligations of the Company in respect of any letters of credit, bankers’ acceptance, security purchase facilities and similar credit transactions; (5) all obligations of the Company in respect of interest rate swap, cap or other agreements, interest rate future or options contracts, currency swap agreements, currency future or option contracts and other similar agreements; (6) all obligations of the type referred to in clauses (1) through (5) of other persons for the payment of which the Company is responsible or liable as obligor, guarantor or otherwise; (7) all obligations of the type referred to in clauses (1) through (6) of other persons secured by any lien on any property or asset of the Company whether or not such obligation is assumed by the Company; and (8) any deferrals, renewals or extensions of any such senior indebtedness. Senior indebtedness does not include the subordinated debt securities issued under the subordinated indenture, any indebtedness that by its terms is subordinated to, or ranks on an equal basis with, subordinated debt securities issued under the subordinated indenture, and any indebtedness between or among the Company and its affiliates, including all other debt securities and guarantees in respect of debt securities issued to any trust, or a trustee of such trust, partnership or other entity affiliated with the Company that is a financing vehicle of the Company in connection with the issuance by such financing vehicle of capital securities or other securities guaranteed by the Company pursuant to an instrument that ranks on an equal basis with or junior in respect of payment to subordinated debt securities issued under the subordinated indenture.

The subordinated indenture defines “general obligations” as all obligations of the Company to make payment on account of claims of general creditors, other than (A) obligations on account of senior indebtedness and (B) obligations on account of subordinated debt securities issued under the subordinated indenture and indebtedness for money borrowed ranking pari passu with or subordinate to subordinated debt securities issued under the subordinated indenture.

If the Board of Governors of the Federal Reserve System (or other Federal banking supervisor that is at the time of determination the Company’s primary Federal banking supervisor) shall promulgate any rule or issue any interpretation defining or describing the term “general creditor” or “general creditors” or “senior indebtedness” for purposes of its criteria for the inclusion of subordinated debt of a bank holding company (including a financial holding company, if applicable) in capital, or otherwise defining or describing the obligations to which subordinated debt of a bank holding company (including a financial holding company, if applicable) must be subordinated to be included in capital, to include any obligations not included in the definition of “senior indebtedness” under the subordinated indenture, the term “general obligations” will mean such obligations as defined or described in the first such rule or interpretation, other than obligations described in clauses (A) and (B) above.

If the maturity of any subordinated debt securities is accelerated, the holders of all senior indebtedness outstanding at the time of such acceleration will first be entitled to receive payment in full of all amounts due thereon before the holders of subordinated debt securities will be entitled to receive any payment upon the principal of (or premium, if any) or interest, if any, on the subordinated debt securities.

No payments on account of principal (or premium, if any) or interest, if any, in respect of the subordinated debt securities may be made if there shall have occurred and be continuing:

In addition, the subordinated indenture also provides for defaults, which are not events of default and do not entitle the holders to accelerate the principal of the subordinated debt securities. The following are defaults under the subordinated indenture with respect to subordinated debt securities of a series:

If there is a default in payment of principal or interest (not cured within 30 days) in connection with any outstanding series of subordinated debt securities and upon demand of the trustee, we will be required to pay the whole principal amount (and premium, if any) and interest, if any, then due and payable on the

Associated Banc-Corp and some of our subsidiaries maintain deposits and conduct other banking transactions with the trustee under each of the senior indenture and the subordinated indenture in the ordinary course of business.

The senior indenture, the subordinated indenture, the senior debt securities, and the subordinated debt securities will be governed by and construed in accordance with the laws of the State of New York.

We have one class of common stock, the Associated Banc-Corp common stock. Of the 250,000,000 shares of our common stock with a par value of $0.01 per share authorized, 150,803,064 shares were outstanding as of May 31, 2024, exclusive of shares held in treasury.

The following summary of the material terms and rights of our common stock is not complete. You should refer to the applicable provision of our Amended and Restated Articles of Incorporation, as amended, for a complete statement of the terms and rights of our common stock.

Holders of our common stock are entitled to receive dividends when, as, and if declared by our board of directors out of our assets legally available for payment, subject to the rights of holders of our Series E and Series F Preferred Stock and any other series of preferred stock that may be designated, issued and outstanding from time to time, if and to the extent so provided under the terms of such series. No share of our common stock is entitled to any preferential treatment with respect to dividends.

The shares of any series of preferred stock underlying the depositary shares will be deposited under a separate deposit agreement between us and a bank or trust company having its principal office in the U.S. and having a combined capital and surplus of at least $50 million, which we refer to in this prospectus as the depositary. We will name the depositary in the applicable prospectus supplement. Subject to the terms of the deposit agreement, each owner of a depositary share will have a fractional interest in all the rights and preferences of the preferred stock underlying the depositary share. Those rights include any dividend, voting, redemption, conversion, exchange, and liquidation rights.

The depositary shares will be evidenced by depositary receipts issued under the deposit agreement. If you purchase fractional interests in shares of the related series of preferred stock, you will receive depositary receipts as described in the applicable prospectus supplement. While the final depositary receipts are being prepared, we may order the depositary to issue temporary depositary receipts substantially identical to the final depositary receipts although not in final form. The holders of the temporary depositary receipts will be entitled to the same rights as if they held the depositary receipts in final form. Holders of the temporary depositary receipts can exchange them for the final depositary receipts at our expense.

We will pay all transfer and other taxes and governmental charges arising solely from the existence of the depositary arrangements. We will pay associated charges of the depositary for the initial deposit of the preferred stock and any redemption of the preferred stock. Holders of depositary shares will pay transfer and other taxes and governmental charges and any other charges that are stated to be their responsibility under the deposit agreement.

We will forward to the depositary, for distribution to the holders of depositary shares, all reports and communications that we must furnish to the holders of the preferred stock.

If the depositary is prevented or delayed by law or any circumstance beyond its control in performing its obligations under the deposit agreement, neither the depositary nor we will be liable. Our obligations and the depositary’s obligations under the deposit agreement will be limited to performance in good faith of duties set forth in the deposit agreement. Neither the depositary nor we will be obligated to prosecute or defend any legal proceeding connected with any depositary shares or preferred stock unless satisfactory indemnity is furnished to us and/or the depositary. We and the depositary may rely upon documents believed to be genuine, written advice of counsel or accountants, or information provided by persons presenting preferred stock for deposit, holders of depositary shares or other persons believed to be competent.

The depositary may resign at any time by delivering notice to us. We may also remove the depositary at any time. Resignations or removals will take effect when a successor depositary is appointed and it accepts the appointment. The successor depositary must be appointed within 60 days after delivery of the notice of resignation or removal and must be a bank or trust company having its principal office in the U.S., and it must have a combined capital and surplus of at least $50 million.

As of May 31, 2024, there were 4,000,000 depositary shares outstanding, each representing a 1/40th ownership interest in a Series E Share, issued and outstanding and 4,000,000 depositary shares outstanding, each representing a 1/40th ownership interest in a Series F Share, issued and outstanding. We deposited the underlying Series E Shares and Series F Shares with a depositary, in each case pursuant to a deposit agreement among us, Equiniti Trust Company, acting as depositary, and the holders from time to time of the depositary receipts evidencing the respective depositary shares.

Subject to the terms of the respective deposit agreements, each holder of a depositary share is entitled, through the depositary, in proportion to the applicable fraction of a Series E Share or Series F Share, as the case may be, represented by that depositary share, to all the rights and preferences of the Series E Share or Series F Share represented thereby (including dividend, voting, redemption and liquidation rights). This description is subject to and qualified in its entirety by reference to our Amended and Restated Articles of Incorporation, including our Articles of Amendment with respect to the Series E Preferred Stock and Series F Preferred Stock, which have been filed as exhibits to our SEC filings.

This section describes the general terms and provisions of the warrants. The prospectus supplement will describe the specific terms of the warrants offered through that prospectus supplement, and any general terms outlined in this section that will not apply to those warrants.

We may issue warrants for the purchase of debt securities, preferred stock, depositary shares, or common stock. Warrants may be issued alone or together with securities offered by any prospectus supplement and may be attached to or separate from those securities. Each series of warrants will be issued under a separate warrant agreement between us and a bank or trust company, as warrant agent, which will be described in the applicable prospectus supplement. The warrant agent will act solely as our agent in connection with the warrants and will not act as an agent or trustee for any holders of warrants.

In this section, we have summarized the material terms and provisions of the warrant agreements and warrants. We have also filed the forms of warrant agreements and the certificates representing the warrants as exhibits to the registration statement of which this prospectus is a part. You should read the applicable forms of warrant agreement and warrant certificate for additional information before you buy any warrants.

If warrants for the purchase of debt securities are offered, the applicable prospectus supplement will describe the terms of those warrants, including the following, if applicable:

If warrants for the purchase of preferred stock, depositary shares or common stock are offered, the applicable prospectus supplement will describe the terms of those warrants, including the following where applicable:

Unless we state otherwise in the applicable prospectus supplement, the warrants will be in registered form only.

A holder of warrant certificates may exchange them for new certificates of different denominations, present them for registration of transfer, and exercise them at the corporate trust office of the warrant agent or any other office indicated in the applicable prospectus supplement.

Until any warrants to purchase debt securities are exercised, the holder of such warrants will not have any of the rights of holders of the debt securities that can be purchased upon exercise, including any right to receive payments of principal, premium, or interest on the underlying debt securities or to enforce covenants in the applicable indenture. Until any warrants to purchase preferred stock, depositary shares, common stock, or other securities are exercised, holders of such warrants will not have any rights of holders of the underlying preferred stock, depositary shares, common stock, or other securities, including any right to receive dividends or to exercise any voting rights.

Each holder of a warrant is entitled to purchase the principal amount of debt securities or number of shares of preferred stock, depositary shares, or shares of common stock, as the case may be, at the exercise price described in the applicable prospectus supplement. After the close of business on the day when the right to exercise terminates, or a later date if we extend the time for exercise, unexercised warrants will become void.

If you comply with the procedures described above, your warrants will be considered to have been exercised when the warrant agent receives payment of the exercise price. After you have completed those procedures, we will, as soon as practicable, issue and deliver to you the debt securities, preferred stock, depositary shares, or common stock that you purchased upon exercise. If you exercise fewer than all of the warrants represented by a warrant certificate, the warrant agent will issue to you a new warrant certificate for

We may amend or supplement a warrant agreement without the consent of the holders of the applicable warrants if the changes are not inconsistent with the provisions of the warrants and do not materially adversely affect the interests of the holders of the warrants. We, along with the warrant agent, may also modify or amend a warrant agreement and the terms of the warrants if a majority of the then-outstanding unexercised warrants affected by the modification or amendment consent. No modification or amendment that accelerates the expiration date, however, or increases the exercise price, reduces the majority consent requirement for any such modification or amendment, or otherwise materially adversely affects the rights of the holders of the warrants may be made without the consent of each holder affected by the modification or amendment.

Except as stated above, the exercise price and number of shares of common stock covered by a common stock warrant will not be adjusted if we issue common stock or any securities convertible into or exchangeable for common stock, or securities carrying the right to purchase common stock, or securities convertible into or exchangeable for common stock.

Holders of common stock warrants may have additional rights under the following circumstances:

If one of the above transactions occurs and holders of our common stock are entitled to receive stock, securities, other property or assets, including cash, with respect to or in exchange for common stock, the holders of the common stock warrants then outstanding will be entitled to receive upon exercise of their common stock warrants the kind and amount of shares of stock and other securities or property that they would have received upon the reclassification, change, consolidation, merger, share exchange, sale, or conveyance if they had exercised their common stock warrants immediately before the transaction.

We may issue securities as part of a unit consisting of any combination of the debt securities, common stock, preferred stock, depositary shares and warrants described in this prospectus. The terms of a series of units may be described in a unit agreement between us and a bank or trust corporation as unit agent. The applicable prospectus supplement will describe the specific terms of any units.

We may sell the securities offered by this prospectus to or through underwriters or dealers, through agents, directly to one or more purchasers, or through a combination of methods. No commission will be payable and no discount will be allowed on any sales we or our affiliates make directly. We may also offer the securities in exchange for our other securities.

Underwriters, dealers, and agents that participate in the distribution of the securities offered under this prospectus may be underwriters as defined in the Securities Act, and any discounts or commissions received by them from us and any profit on the resale of the offered securities by them may be treated as underwriting discounts and commissions under the Securities Act. Any underwriters or agents will be identified and their compensation, including any underwriting discount or commission, will be described in the applicable prospectus supplement. The prospectus supplement will also describe other terms of the offering, including the initial public offering price, any discounts or concessions allowed or re-allowed or paid to dealers and any securities exchanges on which the offered securities may be listed.

The distribution of the securities offered under this prospectus may occur from time to time in one or more transactions at a fixed price or prices, which may be changed, at market prices prevailing at the time of sale, at prices related to the prevailing market prices or at negotiated prices.

In addition, we may enter into derivative transactions with third parties, or sell securities not covered by this prospectus to third parties in privately negotiated transactions. In connection with such a transaction, the third parties may sell securities covered by and pursuant to this prospectus and an applicable prospectus supplement. If so, the third party may use securities borrowed from us or others to settle such sales and may use securities received from us to close out any related short positions. We may also loan or pledge securities covered by this prospectus and an applicable prospectus supplement to third parties, who may sell the loaned securities or, in an event of default in the case of a pledge, sell the pledged securities pursuant to this prospectus and the applicable prospectus supplement.

In connection with an offering of securities, underwriters may purchase and sell these securities in the open market. These transactions may include over-allotment and stabilizing transactions and purchases to cover short positions created by underwriters with respect to the offering. Stabilizing transactions consist of certain bids or purchases for preventing or retarding a decline in the market price of the securities; short positions created by underwriters involve the sale by underwriters of a greater number of securities than they are required to purchase from us in the offering. Underwriters also may impose a penalty bid, by which selling concessions allowed to broker-dealers in respect of the securities sold in the offering may be reclaimed by underwriters if such securities are repurchased by underwriters in stabilizing or covering transactions. These activities may stabilize, maintain, or otherwise affect the market price of the securities, which may be higher than the price that might otherwise prevail in the open market; these activities, if commenced, may be discontinued without notice at any time.

We may determine the price or other terms of the securities offered under this prospectus by use of an electronic auction. We will describe in the applicable prospectus supplement how any auction will be conducted to determine the price or any other terms of the securities, how potential investors may participate in the auction and, when applicable, the nature of the underwriters’ obligations with respect to the auction.

If the securities offered under this prospectus are issued in exchange for our outstanding securities, the applicable prospectus supplement will set forth the terms of the exchange, the identity of and the terms of sale of the securities offered under this prospectus by the selling security holders.

If the applicable prospectus supplement indicates, we will authorize dealers or our agents to solicit offers by institutions to purchase offered securities from us under contracts that provide for payment and delivery on a future date. We must approve all institutions, but they may include, among others:

The selling security holders may engage brokers and dealers, and any brokers or dealers may arrange for other brokers or dealers to participate in effecting sales of the securities. These brokers, dealers or underwriters may act as principals, or as an agent of a selling security holder. Broker-dealers may agree with a selling security holder to sell a specified number of the securities at a stipulated price per share. If the broker-dealer is unable to sell securities acting as agent for a selling security holder, it may purchase as principal any unsold securities at the stipulated price. Broker-dealers who acquire securities as principals may thereafter resell the securities from time to time in transactions in any stock exchange or automated interdealer quotation system on which the securities are then listed, at prices and on terms then prevailing at the time of sale, at prices related to the then-current market price or in negotiated transactions. Broker-dealers may use block transactions and sales to and through broker-dealers, including transactions of the nature described above.

From time to time, one or more of the selling security holders may pledge, hypothecate or grant a security interest in some or all of the securities owned by them. The pledgees, secured parties or persons to whom the securities have been hypothecated will, upon foreclosure in the event of default, be deemed to be selling security holders. The number of a selling security holder’s securities offered under this prospectus will decrease as and when it takes such actions. The plan of distribution for that selling security holder’s securities will otherwise remain unchanged. In addition, a selling security holder may, from time to time, sell the securities short, and, in those instances, this prospectus may be delivered in connection with the short sales and the securities offered under this prospectus may be used to cover short sales.

The selling security holders and any underwriters, brokers, dealers or agents that participate in the distribution of the securities may be deemed to be “underwriters” within the meaning of the Securities Act, and any discounts, concessions, commissions or fees received by them and any profit on the resale of the securities sold by them may be deemed to be underwriting discounts and commissions.

A selling security holder may enter into hedging transactions with broker-dealers and the broker-dealers may engage in short sales of the securities in the course of hedging the positions they assume with that selling security holder, including, without limitation, in connection with distributions of the securities by those broker- dealers. A selling security holder may enter into option or other transactions with broker-dealers that involve the delivery of the securities offered hereby to the broker-dealers, who may then resell or otherwise transfer those securities. A selling security holder may also loan or pledge the securities offered hereby to a broker-dealer and the broker-dealer may sell the securities offered hereby so loaned or upon a default may sell or otherwise transfer the pledged securities offered hereby.

The selling security holders and other persons participating in the sale or distribution of the securities will be subject to applicable provisions of the Exchange Act and the related rules and regulations adopted by the SEC, including Regulation M. This regulation may limit the timing of purchases and sales of any of the securities by the selling security holders and any other person. The anti-manipulation rules under the Exchange Act may apply to sales of securities in the market and to the activities of the selling security holders and their affiliates. Furthermore, Regulation M may restrict the ability of any person engaged in the distribution of the securities to engage in market-making activities with respect to the particular securities being distributed for a period of up to five business days before the distribution. These restrictions may affect