Table of Contents

As filed with the Securities and Exchange Commission on September 29, 2026

Registration No. –333-

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form S-3

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

MERCANTILE BANK CORPORATION

(Exact name of registrant as specified in its charter)

310 Leonard Street NW, Grand Rapids, 49504

Michigan

Telephone: 616-406-3000

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Raymond E. Reitsma
President and Chief Executive Officer
Mercantile Bank Corporation
310 Leonard Street, NW,
Grand Rapids, MI 49504
(616) 406-3000

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copy to:

Bradley J. Wyatt
Greenberg Traurig, LLP
2375 E. Camelback Rd., Suite 800
Phoenix, AZ 85016
Telephone: (602) 445-8057

Approximate date of commencement of proposed sale to the public: From time to time after this registration statement becomes effective, as determined by market conditions and other factors.

If the only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, please check the following box. ☐

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box.☑

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box. ☑

If this Form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box. ☐

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

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 7(a)(2)(B) of the Securities Act ☐

PROSPECTUS

Common Stock

Preferred Stock

Debt Securities

Depositary Shares

Stock Purchase Contracts

Stock Purchase Units

Subscription Rights

Warrants

Units

Mercantile Bank Corporation (“we,” “us,” “our,” “Mercantile” or the “Company”) may offer from time to time to sell, in one or more series, and in any combination, the securities described in this prospectus. This prospectus describes the general terms of these securities and the general manner in which we will offer them. Each time that we offer and sell securities using this prospectus, we will provide a supplement to this prospectus that contains specific information about the securities and their terms and the manner in which we will offer them for sale. Any supplement to this prospectus may also add or update information contained in this prospectus. You should carefully read this prospectus and any supplement to this prospectus, as well as any documents we have incorporated into this prospectus by reference, before you invest in any of these securities. This prospectus may not be used to consummate a sale of securities unless accompanied by the applicable prospectus supplement. References herein to “prospectus supplement” are deemed to refer to any pricing supplement or free writing prospectus describing the specific pricing or other terms of the applicable offering that we prepare and distribute.

We or any selling security holders may offer and sell these securities in any combination from time to time in one or more offerings. The preferred stock, debt securities, depositary shares, stock purchase contracts, stock purchase units, subscription rights, units, and warrants, may be convertible into or exercisable or exchangeable for our common stock or our other securities. This prospectus provides you with a general description of the securities we may offer.

Our common stock is listed on the NASDAQ Global Select Market under the symbol “MBWM”. Our principal executive offices are located at 310 Leonard Street, NW, Grand Rapids, MI 49504 and our telephone number is (616) 406-3000. On September 28, 2026, the last reported sale price of our common stock was $59.38. We have not yet determined whether any of the other securities that may be offered pursuant to this prospectus will be listed on any exchange.

This prospectus is not an offer to sell these securities, and it is not soliciting an offer to buy these securities, in any state or jurisdiction where the offer or sale is not permitted.

The securities offered by this prospectus are not savings accounts, deposits or other obligations of a bank or savings association and are not insured by the Federal Deposit Insurance Corporation or any other government agency or instrumentality.

Investing in our securities involves risks. You should refer to the section entitled “Risk Factors” on page 2 of this prospectus, as well as the risk factors included in the applicable prospectus supplement and in certain of our periodic reports and other information that we file with the Securities and Exchange Commission and carefully consider that information before buying our securities. The securities may be offered directly by us or by any selling security holder from time to time, through agents designated by us or to or through underwriters, brokers or dealers. We will provide specific information about any selling security holders in one or more supplements to this prospectus. For additional information on the methods of sale, you should refer to the section entitled “Plan of Distribution” in this prospectus. If any underwriters are involved in the sale of any securities with respect to which this prospectus is being delivered, the names of such underwriters and any applicable commissions or discounts will be set forth in a prospectus supplement. The price to the public of such securities and the net proceeds we expect to receive from such sale will also be set forth in a prospectus supplement.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

This prospectus is dated September 29, 2026.

TABLE OF CONTENTS

ABOUT THIS PROSPECTUS

This prospectus is part of an automatic shelf registration statement that we filed with the Securities and Exchange Commission (the “SEC”) as a “well known seasoned issuer” as defined in Rule 405 under the Securities Act of 1933, as amended (the “Securities Act”) utilizing a shelf registration process. We are a “well-known seasoned issuer,” as defined in Rule 405 under the Securities Act, and are eligible to use this automatic shelf registration statement on Form S-3 pursuant to General Instruction I.D. of Form S-3. As a well-known seasoned issuer, this registration statement becomes effective automatically upon filing with the SEC pursuant to Rule 462(e) under the Securities Act. Under this shelf registration process, we may offer and sell the securities described in this prospectus in one or more offerings. In addition, selling security holders to be named in a prospectus supplement may sell certain of our securities from time to time.

This prospectus provides you with a general description of the securities that we or any selling security holder may offer. Each time we or any selling security holder offers our securities, we or such selling security holder will provide a prospectus supplement that will contain specific information about the terms of that offering. That prospectus supplement may include a discussion of any risk factors or other special considerations that apply to those securities. The prospectus supplement may also add, update, supplement or change information contained or incorporated by reference in this prospectus. If there is any inconsistency between the information in this prospectus and the applicable prospectus supplement, you should rely on the information in that prospectus supplement. You should read this prospectus (including the documents incorporated by reference) and any applicable prospectus supplement together with the additional information referred to under the heading “Where You Can Find More Information.”

The rules of the SEC allow us to incorporate by reference information into this prospectus. The information incorporated by reference is considered to be a part of this prospectus, and information that we file later with the SEC will automatically update and supersede this information.

We have not authorized anyone to provide you with different or additional information. Neither we nor anyone acting on our behalf is making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information contained or incorporated by reference in this prospectus or any prospectus supplement is accurate as of its date only, and any information we have incorporated by reference is accurate only as of the date of the document incorporated by reference, regardless of the time of delivery of this prospectus, any applicable prospectus supplement, or any sale of a security. Our business, financial condition, results of operations and prospects may have changed since those dates. If there is any inconsistency between the information in this prospectus and any prospectus supplement, you should rely on the information contained in that prospectus supplement. This prospectus may not be used to consummate a sale of securities unless it is accompanied by a prospectus supplement.

This prospectus, any accompanying prospectus supplement, may contain estimates and other information concerning our target markets that are based on industry publications, surveys and forecasts. This information involves a number of assumptions and limitations and you are cautioned not to give undue weight to this information. Please read the section of this prospectus entitled “Cautionary Note Regarding Forward-Looking Statements.” The industry in which we operate is subject to a high degree of uncertainty and risk due to a variety of factors, including those described under the heading “Risk Factors” contained in the applicable prospectus, and in our most recent Annual Report on Form 10-K and any subsequently filed Quarterly Reports on Form 10-Q, as well as any amendments thereto reflected in subsequent filings with the SEC. These and other factors could cause actual results to differ materially from those expressed in such publications, surveys and forecasts.

This prospectus contains summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to herein have been filed, will be filed or will be incorporated by reference as exhibits to the registration statement of which this prospectus is a part, and you may obtain copies of those documents as described below under the section entitled “Where You Can Find More Information.” This prospectus does not constitute an offer to sell, or a solicitation of an offer to buy, any securities, in any jurisdiction to or from any person to whom it is unlawful to make any such offer or solicitation in such jurisdiction.

RISK FACTORS

An investment in our securities involves certain risks. Before making an investment decision, you should carefully read and consider the risk factors incorporated by reference in this prospectus, as the same may be updated from time to time by our future filings with the SEC, as well as those contained in any applicable prospectus supplement. Our business, financial condition or results of operations could be materially adversely affected by any of these risks. The trading price of our securities could decline due to any of these risks, and you may lose all or part of your investment. This prospectus and documents incorporated by reference in this prospectus also contain forward-looking statements that involve risks and uncertainties. Our actual results could differ materially from those anticipated in these forward-looking statements as a result of certain factors, including the risks faced by us.

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus and the documents incorporated by reference contain certain forward-looking statements within the meaning of Section 27A of the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), such as discussions of the Company’s financial condition, results of operations, plans, objectives, future performance and the business of the Company. The Company intends such forward-looking statements to be covered by the safe harbor provisions for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995 and is including this statement for purposes of these safe harbor provisions. Forward-looking statements, which are based on certain assumptions and describe future plans, strategies and expectations of the Company are identified by use of the words “anticipate,” “believe,” “could,” “estimate,” “expect,” “future,” “indicate,” “intend,” “likely,” “may,” “plan,” “project,” “should,” “strategy,” “will,” and variations of such words and similar expressions are intended to identify such forward-looking statements. These statements are not guarantees of future performance and involve certain risks, uncertainties and assumptions (“Future Factors”) that are difficult to predict with regard to timing, extent, likelihood, and degree of occurrence. Therefore, actual results and outcomes may materially differ from what may be expressed or forecasted in such forward-looking statements. We undertake no obligation to update, amend, or clarify forward-looking statements, whether as a result of new information, future events (whether anticipated or unanticipated), or otherwise.

Future Factors include, among others, adverse changes in interest rates and interest rate relationships; increasing rates of inflation and slower growth rates; significant declines in the value of commercial real estate; market volatility; demand for products and services; climate impacts; labor markets; the degree of competition by traditional and non-traditional financial services companies; changes in banking regulation or actions by bank regulators; changes in tax laws; changes in prices, levies, and assessments; the impact of technological advances; potential cyber-attacks, information security breaches, and other criminal activities; litigation liabilities; governmental and regulatory policy changes; the outcomes of existing or future contingencies; trends in customer behavior as well as their ability to repay loans; changes in local real estate values; damage to our reputation resulting from adverse publicity, regulatory actions, litigation, operational failures, and the failure to meet client expectations and other facts; changes in the national and local economies, and unstable political and economic environments; difficulties integrating the business of Eastern Michigan Bank; focus of time and effort of our management team toward integration efforts; the anticipated benefits of the acquisition may not be realized; risks related to the indebtedness incurred to finance the merger; and risks associated with the ongoing conversion of the core processing systems. These are representative of the Future Factors that could cause a difference between an ultimate actual outcome and a forward-looking statement.

Additional factors that could cause our performance or results to differ from those projected will be described under “Risk Factors” in the applicable prospectus supplement and are described in our most recent Annual Report on Form 10-K, and in our updates to those Risk Factors in our Quarterly Reports on Form 10-Q and Current Reports on Form 8-K, together with all of the other information appearing in this prospectus or incorporated by reference into this prospectus and any applicable prospectus supplement. In addition, there are other factors that may impact any public company, including ours, which could have a material adverse effect on the operations and future prospects of the Company and its subsidiaries.

MERCANTILE BANK CORPORATION

Mercantile is a registered bank holding company under the Bank Holding Company Act of 1956, as amended. Mercantile was organized on July 15, 1997, under the laws of the State of Michigan, primarily for the purpose of holding all of the stock of Mercantile Bank, a Michigan state banking company (“Mercantile Bank”). During the third quarter of 2013, Mercantile filed an election to become a financial holding company which became effective April 14, 2014.

Mercantile common stock is listed on the NASDAQ Global Select Market under the symbol “MBWM.”

Mercantile’s banking operations are conducted through Mercantile Bank and other subsidiaries, including a bank subsidiary acquired at the end of 2025, Eastern Michigan Bank, a Michigan state banking company (“Eastern Michigan Bank”), that is expected to be merged into Mercantile Bank. Mercantile’s banks operate a combined 53 office locations, provide commercial banking services, primarily to small- to medium-sized businesses, and retail banking services. Mercantile Bank’s main office is located is located in Grand Rapids, Michigan, and its operations are centered around the West and Central portions of Michigan. It also has banking offices located in the metropolitan Detroit area, Mt. Pleasant, Lansing, Kalamazoo, and Holland. Eastern Michigan Bank’s main office is located in Croswell, Michigan, and its operations are centered around Eastern Michigan. Mercantile’s banks own a combined 10 automated teller machines and 55 video banking machines at a majority of office locations. Mercantile’s website address is www.ir.mercbank.com. Information contained on Mercantile’s website does not constitute part of, and is not incorporated into, this prospectus.

Mercantile Insurance Center, Inc., a subsidiary of Mercantile Bank, commenced operations and acquired an existing self-insurance agency in 2002. An Agency and Institution Agreement was entered into among Mercantile Insurance Center, Inc., Mercantile Bank, and Hub International for the purpose of providing programs of mass marketed personal lines of insurance. Mercantile Insurance Center, Inc. offers insurance products such as private passenger automobile, homeowners, personal inland marine, boat owners, recreational vehicle, dwelling fire, umbrella policies, small business, and life insurance products, all of which are provided by and written through companies that have appointed Hub International as their agent. To date, Mercantile Insurance Center, Inc. has not provided the insurance products listed above and has no plans to do so.

Additional information about us is included in our filings with the SEC, which are incorporated by reference into this prospectus. See “Where You Can Find More Information” and “Incorporation of Certain Information by Reference” in this prospectus.

USE OF PROCEEDS

Unless the applicable prospectus supplement states otherwise, we anticipate the net proceeds we receive from the sale of the securities offered hereby will be used for general corporate purposes, which may include, among other things, investments in or advances to our subsidiaries, working capital, capital expenditures, stock repurchases, debt repayment or the financing of possible acquisitions. The applicable prospectus supplement relating to a particular offering of securities by us will identify the particular use of proceeds for that offering. Until we use the net proceeds from an offering, we may place the net proceeds in temporary investments or hold the net proceeds in deposit accounts at the banking subsidiaries of the Company.

We will not receive any of the proceeds from sales of securities by selling security holders.

SELLING SECURITY HOLDERS

If the registration statement of which this prospectus forms a part is used by selling security holders for the resale of any securities registered thereunder pursuant to a registration rights agreement to be entered into by us with such selling security holders or otherwise, information about such selling security holders, their beneficial ownership of our securities and their relationship with us will be set forth in a prospectus supplement, or in other filings we make with the SEC under the Exchange Act that are incorporated by reference into the registration statement. Any such prospectus supplement may also add, update or change the information regarding the selling security holders, the number or type of securities beneficially owned by them and the number or type of securities being offered by them. The identities of any selling security holders, the securities to be registered on their behalf and any material relationships between such selling security holders and us will be set forth in one or more prospectus supplements, or other filings incorporated by reference into this prospectus, as applicable. The registration statement of which this prospectus forms a part may be used, to the extent permitted by applicable SEC rules, for resales of securities by selling security holders identified from time to time in one or more prospectus supplements.

DESCRIPTION OF SECURITIES WE MAY OFFER

This prospectus contains summary descriptions of the common stock, preferred stock, debt securities, depositary shares, stock purchase contracts, stock purchase units, subscription rights, warrants, and units, that we may offer and sell from time to time. When one or more of these securities are offered in the future, a prospectus supplement will explain the particular terms of the securities and the extent to which these general provisions may apply. The following summary descriptions and any summary descriptions in the applicable prospectus supplement do not purport to be complete descriptions of the terms and conditions of each security and are qualified in their entirety by reference to our Articles of Incorporation, as amended (our “Articles of Incorporation”), our Amended and Restated Bylaws (our “Bylaws”), the Michigan Business Corporation Act (the “MBCA”) and any other documents referenced in such summary descriptions and from which such summary descriptions are derived. If any particular terms of a security described in the applicable prospectus supplement differ from any of the terms described in this prospectus, you should rely on the prospectus supplement.

We may issue securities in book-entry form through one or more depositaries named in the applicable prospectus supplement. Each sale of a security in book-entry form will settle in immediately available funds through the applicable depositary, unless otherwise stated. We will issue the securities in registered form, without coupons, although we may issue the securities in bearer form if so specified in the applicable prospectus supplement. If any securities are to be listed or quoted on a securities exchange or quotation system, the applicable prospectus supplement will say so.

DESCRIPTION OF CAPITAL STOCK

The following is a summary of the material terms, limitations, voting powers and relative rights of our capital stock as contained in our Articles of Incorporation, which is incorporated by reference herein. This summary does not purport to be a complete description of the terms and conditions of our capital stock in all respects and is subject to and qualified in its entirety by reference to our Articles of Incorporation, our Bylaws, the MBCA and any other documents referenced in the summary descriptions and from which the summary descriptions are derived. Although we believe this summary covers the material terms and provisions of our capital stock set forth in our Articles of Incorporation, it may not contain all of the information that is important to you.

General

Our Articles of Incorporation, including all amendments thereto, authorize the issuance of up to 40,000,000 shares of common stock, no par value per share, and up to 1,000,000 shares of preferred stock, no par value per share. As of September 25, 2026, there were 17,287,385 shares of our common stock issued and outstanding, and no shares of preferred stock were outstanding.

Common Stock

Voting Rights. Except as otherwise required by law or by any amendment to our Articles of Incorporation, each holder of common stock shall have one vote for each share of stock held by him of record on the books of the corporation on all matters voted upon by the shareholders.

Dividend Rights. Subject to the preferential dividend rights, if any, applicable to shares of preferred stock and subject to applicable requirements, if any, with respect to the setting aside of sums for purchase, retirement, or sinking funds for preferred stock, the holders of common stock shall be entitled to receive, to the extent permitted by law, such dividends as may be declared from time to time by the board of directors.

Liquidation Rights. In the event of the voluntary or involuntary liquidation, dissolution, distribution of assets or winding up of the corporation, after distribution in full of the preferential amounts, if any, to be distributed to the holders of shares of preferred stock, holders of common stock shall be entitled to receive all of the remaining assets of the corporation of whatever kind available for distribution to shareholders ratably in proportion to the number of shares of common stock held by them respectively. The board of directors may distribute in kind to the holders of common stock such remaining assets of the corporation or may sell, transfer, or otherwise dispose of all or any part of such remaining assets to any other corporation, trust or entity, or any combination thereof, and may sell all or any part of the consideration so received and distribute any balance thereof in kind to holders of common stock. The merger or consolidation of the corporation into or with any other corporation, or the merger of any other corporation into it, or any purchase or redemption of shares of stock of the corporation of any class, shall not be deemed to be dissolution, liquidation or winding up of the corporation for the purposes of this paragraph.

Other Rights. Such numbers of shares of common stock as may from time to time be required for such purpose shall be reserved for issuance (i) upon conversion of any shares of preferred stock or any obligation of the corporation convertible into shares of common stock which is at the time outstanding or issuable upon exercise of any options or warrants at the time outstanding and (ii) upon exercise of any options, warrants or rights at the time outstanding to purchase shares of common stock.

Stock Exchange Listing. Mercantile’s common stock is listed on the NASDAQ Global Select Market under the symbol “MBWM”.

Transfer Agent. Mercantile’s transfer agent is Computershare Trust Company, N.A.

Preferred Stock

General. We may issue up to 1,000,000 shares of preferred stock, no par value per share, from time to time in one or more series. Our board of directors, without further approval of our stockholders, has the authority to fix the dividend rights and terms, conversion rights, voting rights, redemption rights and terms, liquidation preferences, sinking funds and any other rights, preferences, privileges and restrictions applicable to each series of preferred stock. The issuance of preferred stock, while providing flexibility in connection with possible acquisitions and other corporate purposes, could, among other things, adversely affect the voting power of the holders of our common stock.

We will describe the particular terms of any series of preferred stock being offered in the applicable prospectus supplement relating to that series of preferred stock. Those terms may include:

The shares of preferred stock will, when issued against full payment of their purchase price, be fully paid and nonassessable. Unless otherwise specified in the prospectus supplement relating to a series of preferred stock, each series of preferred stock will rank equally as to dividends and liquidation rights in all respects with each other series of preferred stock. The rights of holders of shares of each series of preferred stock will be subordinate to those of our general creditors.

Voting Rights. The voting rights of preferred stock of any series being offered will be described in the applicable prospectus supplement.

Dividend Rights. If you purchase preferred stock being offered by use of this prospectus and an applicable prospectus supplement, you will be entitled to receive, when, as and if declared by our board of directors, dividends at the rates and on the dates set forth in the prospectus supplement. Dividend rates may be fixed, variable or both. The nature, amount, rates, timing and other details of dividend rights for a series of preferred stock will be described in the applicable prospectus supplement and will be payable in preference to, or in such relation to, the dividends payable on any other class or classes or series of our stock, as described in the applicable prospectus supplement. We are subject to various regulatory policies and requirements relating to the payment of dividends, including requirements to maintain adequate capital above regulatory minimums.

Liquidation Rights. In the event that we liquidate, dissolve or wind-up our affairs, either voluntarily or involuntarily, holders of our preferred stock will be entitled to receive liquidating distributions in the amount set forth in the applicable prospectus supplement, plus accrued and unpaid dividends, if any, before we make any distribution of assets to the holders of our common stock or any junior preferred stock. If we fail to pay in full all amounts payable with respect to preferred stock being offered by us and any stock having the same rank as that series of preferred stock, the holders of the preferred stock and of that other stock will share in any distribution of assets in proportion to the full respective preferential amounts to which they are entitled. After the holders of each series of preferred stock and any stock having the same rank as the preferred stock are paid in full, they will have no right or claim to any of our remaining assets. For any series of preferred stock being offered by this prospectus and an applicable prospectus supplement, neither the sale of all or substantially all of our property or business nor a merger or consolidation by us with any other corporation will be considered a dissolution, liquidation or winding-up of our business or affairs.

Redemption. The terms, if any, on which shares of a series of preferred stock being offered may be redeemed will be described in the applicable prospectus supplement. The preferred stock of a series may be redeemed in such amount or amounts, and at such time or times, if any, as may be provided in respect of that particular series of preferred stock. Preferred stock may be redeemed by the Company only to the extent legally permissible and/or as approved by our banking regulators.

Conversion Rights. The applicable prospectus supplement will state the terms, if any, on which shares of a series of preferred stock being offered are convertible into shares of our common stock or another series of our preferred stock.

Anti-Takeover Considerations and Special Provisions of Mercantile Bank Corporation’s Articles of Incorporation, Bylaws, and Michigan Law

Provisions of the MBCA and our Articles of Incorporation and Bylaws could make it more difficult to acquire Mercantile by means of a tender offer, a proxy contest or otherwise, or to remove incumbent officers and directors. These provisions, summarized below, are intended to discourage coercive takeover practices and inadequate takeover bids and to encourage persons seeking to acquire control of Mercantile to first negotiate with its board of directors. We believe that the benefits of these provisions outweigh the disadvantages of discouraging certain takeover or acquisition proposals because, among other things, negotiation of these proposals could result in an improvement of their terms and enhance the ability of its board of directors to maximize shareholder value. However, these provisions may delay, deter or prevent a merger or acquisition of Mercantile that a shareholder might consider is in its best interest, including those attempts that might result in a premium over the prevailing market price of our common stock.

Shareholder Meetings; Requirements for Advance Notice. Our Articles of Incorporation provide that special meetings of the shareholders may be called only by or at the direction of the board of directors or the chairman of the board. In addition, our Bylaws establish advance notice procedures with respect to shareholder proposals and the nomination of candidates for election as director. In order for any matter to be “properly brought” before a meeting, a shareholder will have to comply with such advance notice procedures and provide Mercantile with certain information.

Supermajority Voting for Amendments to Certain Provisions. Any amendment to certain provisions of our Articles of Incorporation, such as provisions relating to nomination, election, or removal of directors, and provisions relating to shareholder action by written consent, requires the affirmative vote of at least 66⅔% of the voting power of all shares of our common stock then outstanding. Our Bylaws may be amended, altered, changed, added to or repealed by the shareholders at any regular or special meeting of the shareholders provided such action is contained in the notice of such meeting, or by the board of directors at any regular or special meeting of the board of directors.

No Cumulative Voting. The MBCA provides that the articles of incorporation may permit cumulative voting in the election of directors. Our Articles of Incorporation do not provide for cumulative voting.

Removal of Directors; Vacancies. Our Articles of Incorporation, provide that directors may be removed only for cause only by the affirmative vote of the holders of at least a majority of the voting power of all the shares of the corporation entitled to vote generally in the election of directors, voting together as a single class. In addition, our Articles of Incorporation provide that only its board of directors may fill vacant directorships, including newly created seats, by the affirmative vote of the majority of remaining directors.

Shareholder Action by Written Consent. The MBCA permits any action required to be taken at any annual or special meeting of the shareholders to be taken without a meeting, without prior notice and without a vote if a consent in writing, setting forth the action so taken, is signed by the holders of outstanding stock having not less than the minimum number of votes that would be necessary to authorize or take such action at a meeting at which all shares of stock entitled to vote thereon were present and voted, unless the articles of incorporation provide otherwise. Our Articles of Incorporation provide that any action to be taken by the shareholders must be effected at a duly called annual or special meeting of shareholders and may not be effected by written consent.

Limitations on Liability and Indemnification of Officers and Directors. Our Articles of Incorporation and Bylaws provide that the corporation will indemnify its directors and officers, and may indemnify its employees and other agents, to the fullest extent permitted by Michigan law. Michigan law prohibits the articles of incorporation from limiting the liability of directors for the following: (i) for any breach of the director’s duty of loyalty to the corporation or its shareholders, (ii) for acts or omissions not in good faith or that involve intentional misconduct or a knowing violation of law, (iii) a violation of Section 551(1) of the MBCA, or (iv) for any transaction from which the director derived any improper personal benefit.

If Michigan law is amended to authorize corporate action further eliminating or limiting the personal liability of a director, then the liability of Mercantile’s directors will be eliminated or limited to the fullest extent permitted by Michigan law, as so amended. Our Articles of Incorporation do not eliminate a director’s duty of care and, in appropriate circumstances, equitable remedies, such as injunctive or other forms of non-monetary relief, remain available under Michigan law. This provision also does not affect a director’s responsibilities under any other laws, such as the federal securities laws or other state or federal laws. Under our Articles of Incorporation and Bylaws, we will also be empowered to purchase insurance on behalf of any person whom it is required or permitted to indemnify.

The limitation of liability and indemnification provisions provided for in our Articles of Incorporation and Bylaws may discourage shareholders from bringing a lawsuit against directors for breach of their fiduciary duties. They may also reduce the likelihood of derivative litigation against directors and officers, even though an action, if successful, might benefit Mercantile and its shareholders. Moreover, a shareholder’s investment may be harmed to the extent it pays the costs of settlement and damage awards against directors and officers pursuant to these indemnification provisions. Insofar as indemnification for liabilities arising under the Securities Act may be permitted to Mercantile’s directors, officers and controlling persons pursuant to the foregoing provisions, or otherwise, Mercantile has been advised that, in the opinion of the SEC, such indemnification is against public policy as expressed in the Securities Act, and is, therefore, unenforceable. There is no pending litigation or proceeding naming any of Mercantile’s directors or officers as to which indemnification is being sought, nor is Mercantile aware of any pending or threatened litigation that may result in claims for indemnification by any director or officer.

Authorized but Unissued Shares. Mercantile’s authorized but unissued shares of common stock and preferred stock are available for future issuances without shareholder approval, except as required by the listing standards of the NASDAQ Global Select Market and could be utilized for a variety of corporate purposes, including future offerings to raise additional capital, acquisitions and employee benefit plans. The existence of authorized but unissued and unreserved common stock and preferred stock could render more difficult or discourage an attempt to obtain control of the Company by means of a proxy contest, tender offer, merger or otherwise.

Banking Laws. The ability of a third party to acquire the Company is also subject to applicable banking laws and regulations. The Bank Holding Company Act of 1956 (the “BHCA”) and the regulations thereunder require any “bank holding company” (as defined in the BHCA) to obtain the approval of the Federal Reserve prior to acquiring more than 5% of the outstanding shares of a class of our voting stock. As a financial holding company, the Company is a bank holding company under the BHCA. Any person other than a bank holding company is required to obtain prior approval of the Federal Reserve to acquire 10% or more of the outstanding shares of a class of our voting stock under the Change in Bank Control Act of 1978. Federal law also prohibits any person or company from acquiring “control” of an FDIC-insured depository institution or its holding company without prior notice to the appropriate federal bank regulator. On January 30, 2020, the Federal Reserve issued a final rule (which became effective September 30, 2020) that clarified and codified the Federal Reserve’s standards for determining whether one company has control over another. The final rule established four categories of tiered presumptions of control that are based on the percentage of voting shares held by the investor (less than 5%, 5-9.9%, 10-14.9% and 15-24.9%) and the presence of other indicia of control. As the percentage of ownership increases, fewer indicia of control are permitted without falling outside the presumption of noncontrol. These indicia of control include nonvoting equity ownership, director representation, management interlocks, business relationship and restrictive contractual covenants. Under the final rule, investors can hold up to 24.9% of the voting securities and up to 33% of the total equity of a company without necessarily having a controlling influence. For purposes of calculating ownership thresholds under these banking regulations, bank regulators would likely take the position that the minimum number of shares, and could take the position that the maximum number of shares, of the Company’s common stock that a holder is entitled to receive pursuant to securities convertible into or settled in the Company’s common stock, including pursuant to the Company’s warrants to purchase the Company’s common stock held by such holder, must be taken into account in calculating a shareholder’s aggregate holdings of the Company’s common stock.

DESCRIPTION OF DEBT SECURITIES

General

The debt securities that we may offer using this prospectus consist of notes, debentures or other evidences of indebtedness. Any debt securities that we offer and sell will be our direct obligations. Debt securities may be issued in one or more series. All debt securities of any one series need not be issued at the same time, and unless otherwise provided, a series of debt securities may be reopened, without the consent of the holders of outstanding debt securities, for issuance of additional debt securities of that series or to establish additional terms of that series of debt securities (with such additional terms applicable only to unissued or additional debt securities of that series).

As required by the Trust Indenture Act of 1939, as amended (the “Trust Indenture Act”), for all debt securities that are publicly offered, our debt securities will be governed by a document called an indenture to be entered into by and between us and such bank or trust company that we select to act as trustee (the “trustee”). The form of indenture is subject to any amendments or supplements that we may enter into with the trustee(s). The indenture is filed as an exhibit to the registration statement of which this prospectus forms a part. The following description and any description in a prospectus supplement is a summary only and is subject to, and qualified in its entirety by reference to the terms and provisions of the indentures and any supplemental indentures that we file with the SEC in connection with an issuance of any series of debt securities. You should read all of the provisions of the indentures, including the definitions of certain terms, as well as any supplemental indentures that we file with the SEC in connection with the issuance of any series of debt securities. These summaries set forth certain general terms​ and provisions of the securities to which any prospectus supplement may relate. The specific terms and provisions of a series of debt securities and the extent to which the general terms and provisions may also apply to a particular series of debt securities will be described in the applicable prospectus supplement.

Each prospectus supplement will specify the particular terms of the securities offered. These provisions may include, among other things and to the extent applicable, the following:

Unless otherwise indicated in the applicable prospectus supplement, we will issue debt securities in fully registered form without coupons and in denominations of $1,000 and in integral multiples of $1,000, and interest will be computed on the basis of a 360-day year of twelve 30-day months. If any interest payment date or the maturity date falls on a day that is not a business day, then the payment will be made on the next business day without additional interest and with the same effect as if it were made on the originally scheduled date.

Unless otherwise indicated in the applicable prospectus supplement, the trustee will act as paying agent and registrar for the debt securities under the indenture. We may also act as paying agent under the indenture.

The applicable prospectus supplement will contain a description of U.S. federal income tax consequences relating to the debt securities, to the extent applicable.

Covenants

The applicable prospectus supplement will describe any covenants, such as restrictive covenants restricting us or any of our subsidiaries from incurring, issuing, assuming or guarantying any indebtedness or restricting us or any of our subsidiaries from paying dividends or acquiring any of our or its capital stock.

Consolidation, Merger and Transfer of Assets

Unless we indicate otherwise in the applicable prospectus supplement, the indenture will permit a consolidation or merger between us and another entity and/or the sale, conveyance or lease by us of all or substantially all of our property and assets; provided, however, that:

If we consolidate or merge with or into any other entity, or sell or lease all or substantially all of our assets in compliance with the terms and conditions of the indenture, the resulting or acquiring entity will be substituted for us in the indenture and the debt securities with the same effect as if it had been an original party to the indenture and the debt securities. As a result, such successor entity may exercise our rights and powers under the indenture and the debt securities, in our name, and, except in the case of a lease, we will be released from all our liabilities and obligations under the indenture and under the debt securities.

Notwithstanding the foregoing, we may transfer all of our property and assets to another entity if, immediately after giving effect to the transfer, such entity is our wholly-owned subsidiary. The term “wholly-owned subsidiary” means any subsidiary in which we and/or our other wholly-owned subsidiaries own all of the outstanding capital stock.

Modification and Waiver

Unless we indicate otherwise in the applicable prospectus supplement, under the indenture, some of our rights and obligations and some of the rights of the holders of the debt securities may be modified or amended with the consent of the holders of not less than a majority in aggregate principal amount of the outstanding debt securities affected by the modification or amendment. However, the following modifications and amendments will not be effective against any holder without its consent:

Under the indenture, the holders of not less than a majority in aggregate principal amount of the outstanding debt securities may, on behalf of all holders of the debt securities:

Events of Default

Unless we indicate otherwise in the applicable prospectus supplement, “event of default” under the indenture will mean, with respect to any series of debt securities, any of the following:

Unless we indicate otherwise in the applicable prospectus supplement, if an event of default occurs and continues, the trustee or the holders of not less than 25% in aggregate principal amount of the outstanding debt securities of such series may declare the entire principal of all the debt securities to be due and payable immediately, except that, if the event of default described in the fourth bullet point above occurs, the entire principal of all of the debt securities of such series will become due and payable immediately without any act on the part of the trustee or holders of the debt securities. If such a declaration occurs, the holders of a majority of the aggregate principal amount of the outstanding debt securities of such series can, subject to conditions, rescind the declaration.

The indenture requires us to furnish to the trustee, not less often than annually, a certificate from our principal executive officer, principal financial officer or principal accounting officer, as the case may be, as to such officer’s knowledge of our compliance with all conditions and covenants under the indenture. The trustee may withhold notice to the holders of debt securities of any default, except defaults in the payment of principal of, or interest on, any debt securities if the trustee in good faith determines that the withholding of notice is in the interests of the holders. For purposes of this paragraph, “default” means any event which is, or after notice or lapse of time or both would become, an event of default under the indenture.

The trustee is not obligated to exercise any of its rights or powers under the indenture at the request, order or direction of any holders of debt securities, unless the holders offer the trustee satisfactory security or indemnity. If satisfactory security or indemnity is provided, then, subject to other rights of the trustee, the holders of a majority in aggregate principal amount of the outstanding debt securities may direct the time, method and place of:

The holder of a debt security will have the right to begin any proceeding with respect to the indenture or for any remedy only if:

However, the holder of any debt security will have an absolute right to receive payment of principal of, and interest on, the debt security when due and to institute suit to enforce payment.

Satisfaction and Discharge; Defeasance

Satisfaction and Discharge of Indenture. Unless otherwise indicated in the applicable prospectus supplement, if at any time,

then the indenture shall cease to be of further effect with respect to the debt securities of such series, except for (a) rights of registration of transfer and exchange, and our right of optional redemption, (b) substitution of mutilated, defaced, destroyed, lost or stolen debt securities, (c) rights of holders to receive payments of principal thereof and interest thereon upon the original stated due dates therefor (but not upon acceleration) and remaining rights of the holders to receive mandatory sinking fund payments, if any, (d) the rights, powers, trusts, duties and immunities of the trustee under the indenture and our obligations in connection therewith, and (e) the rights of the holders of such series of debt securities as beneficiaries thereof with respect to the property so deposited with the trustee payable to all or any of them.

Defeasance and Covenant Defeasance. Unless otherwise indicated in the applicable prospectus supplement, we may elect with respect to any debt securities of any series either:

We must comply with the following conditions before the defeasance or covenant defeasance can be effected:

In connection with defeasance, any irrevocable trust agreement contemplated by the indenture must include, among other things, provision for (a) payment of the principal of and interest on such debt securities, if any, appertaining thereto when due (by redemption, sinking fund payments or otherwise), (b) the payment of the expenses of the trustee incurred or to be incurred in connection with carrying out such trust provisions, (c) rights of registration, transfer, substitution and exchange of such debt securities in accordance with the terms stated in the indenture, and (d) the rights, powers, trusts, duties and immunities of the trustee under the indenture and our obligations in connection therewith as stated in the indenture.

The accompanying prospectus supplement may further describe any provisions permitting or restricting defeasance or covenant defeasance with respect to the debt securities of a particular series.

Global Securities

Unless otherwise indicated in the applicable prospectus supplement, each debt security offered by this prospectus will be issued in the form of one or more global debt securities representing all or part of that series of debt securities. This means that we will not issue certificates for that series of debt securities to the holders. Instead, a global debt security representing that series will be deposited with, or on behalf of, a securities depositary and registered in the name of the depositary or a nominee of the depositary. Any such depositary must be a clearing agency registered under the Exchange Act. We will describe the specific terms of the depositary arrangement with respect to a series of debt securities to be represented by a global security in the applicable prospectus supplement.

Notices

We will give notices to holders of the debt securities by mail at the addresses listed in the security register or, with respect to global securities, in accordance with the rules, policies and procedures of the applicable securities depositary.

Governing Law

The indenture and the debt securities will be governed by, and construed in accordance with, the laws of the State of New York, except to the extent the Trust Indenture Act is applicable.

Regarding the Trustee

General. From time to time, we may maintain deposit accounts and conduct other banking transactions with the trustee to be appointed under the indenture or its affiliates in the ordinary course of business.​

Resignation or Removal of Trustee. If the trustee has or acquires a conflicting interest within the meaning of the Trust Indenture Act, the trustee must either eliminate its conflicting interest or resign, to the extent and in the manner provided by, and subject to the provisions of, the Trust Indenture Act and the indenture. Any resignation will require the appointment of a successor trustee under the indenture in accordance with the terms and conditions of the indenture.

The trustee may resign or be removed by us with respect to one or more series of debt securities and a successor trustee may be appointed to act with respect to any such series. The holders of a majority in aggregate principal amount of the debt securities of any series may remove the trustee with respect to the debt securities of such series.

Annual Trustee Report to Holders of Debt Securities. The trustee will be required to submit certain reports to the holders of the debt securities regarding, among other things, the trustee’s eligibility to serve as such, the priority of the trustee’s claims regarding advances made by it, and any action taken by the trustee materially affecting the debt securities.

Certificates and Opinions to Be Furnished to Trustee. The indenture provides that, in addition to other certificates or opinions specifically required by other provisions of the indenture, every application by us for action by the trustee must be accompanied by a certificate from one or more of our officers and an opinion of counsel (who may be our counsel) stating that, in the opinion of the signers, all conditions precedent to such action have been complied with by us.

DESCRIPTION OF DEPOSITARY SHARES

The following is a summary of the general terms of a deposit agreement to govern any depositary shares we may offer representing fractional interests in shares of our preferred stock, the depositary shares themselves and the related depositary receipts. This summary does not purport to be complete in all respects and is subject to and qualified entirely by reference to the relevant deposit agreement and depositary receipt with respect to the depositary shares relating to any particular series of preferred stock. We will file copy of the deposit agreement and form of depositary receipt relating to any depositary shares we issue with the SEC in connection with the offering of any depositary shares. The specific terms of any depositary shares we may offer will be described in the applicable prospectus supplement. If so described in the applicable prospectus supplement, the terms of that series of depositary shares may differ from the general description of terms presented below.

General

We may offer fractional interests in shares of our preferred stock, including in the event that our then authorized but yet undesignated shares of preferred stock is not sufficient to offer full shares of preferred stock. If we offer fractional interests in shares of our preferred stock, we will provide for the issuance by a depositary to the public of receipts for depositary shares, each of which will represent a fractional interest in a share of a particular series of preferred stock.

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 such amount as may be set forth in the applicable prospectus supplement, who we refer to in this section 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, including any dividend, voting, redemption, conversion and liquidation rights.

The depositary shares will be evidenced by depositary receipts issued under the deposit agreement, which will be described in the applicable prospectus supplement. 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. Unless we specify otherwise in the applicable prospectus supplement, you will not be entitled to receive the whole shares of preferred stock underlying the depositary shares.

Dividend Rights

The depositary will distribute all cash dividends or other cash distributions in respect of the preferred stock underlying the depositary shares to each record holder of depositary shares based on the number of the depositary shares owned by that holder on the relevant record date. The depositary will distribute only that amount which can be distributed without attributing to any holder of depositary shares a fraction of one cent, and any balance not so distributed will be added to and treated as part of the next sum received by the depositary for distribution to record holders of depositary shares.

If there is a distribution other than in cash, the depositary will distribute property to the entitled record holders of depositary shares, unless the depositary determines that it is not feasible to make that distribution. In that case the depositary may, with our approval, adopt the method it deems equitable and practicable for making that distribution, including any sale of property and distribution of the net proceeds from this sale to the applicable holders.

Voting Rights

When the depositary receives notice of any meeting at which the holders of the preferred stock may vote, the depositary will mail information about the meeting contained in the notice, and any accompanying proxy materials, to the record holders of the depositary shares relating to the preferred stock. Each record holder of such depositary shares on the record date, which will be the same date as the record date for the preferred stock, will be entitled to instruct the depositary as to how the preferred stock underlying the holder’s depositary shares should be voted.

Conversion or Exchange Rights

If any series of preferred stock underlying the depositary shares is subject to conversion or exchange, the applicable prospectus supplement will describe the rights or obligations of each record holder of depositary receipts to convert or exchange the depositary shares.

Redemption

If the series of the preferred stock underlying the depositary shares is subject to redemption, all or a part of the depositary shares will be redeemed from the redemption proceeds of that series of the preferred stock held by the depositary. The redemption price per depositary share will bear the same relationship to the redemption price per share of preferred stock that the depositary share bears to the underlying preferred stock. Whenever we redeem preferred stock held by the depositary, the depositary will redeem, as of the same redemption date, the number of depositary shares representing the preferred stock redeemed. If less than all the depositary shares are to be redeemed, the depositary shares to be redeemed will be selected by lot or pro rata as determined by the depositary.

After the date fixed for redemption, the depositary shares called for redemption will no longer be outstanding. When the depositary shares are no longer outstanding, all rights of the holders will cease, except the right to receive money or other property that the holders of the depositary shares were entitled to receive upon the redemption. Payments will be made when holders surrender their depositary receipts to the depositary.

Taxation

Owners of depositary shares will be treated for U.S. federal income tax purposes as if they were owners of the preferred stock represented by the depositary shares. If necessary, the applicable prospectus supplement will provide a description of U.S. federal income tax consequences relating to the purchase and ownership of the depositary shares and the preferred stock represented by the depositary shares.

Amendment and Termination of the Deposit Agreement

The form of depositary receipt evidencing the depositary shares and any provision of the deposit agreement may be amended by agreement between us and the depositary at any time. However, certain amendments as specified in the applicable prospectus supplement will not be effective unless approved by the record holders of at least a majority of the depositary shares then-outstanding. A deposit agreement may be terminated by us or the depositary only if:

Charges of Depositary

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 in the deposit agreement.

Resignation and Removal of Depositary

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.

DESCRIPTION OF STOCK PURCHASE CONTRACTS AND STOCK PURCHASE UNITS

We may issue stock purchase contracts, including contracts obligating holders to purchase from us, and us to sell to such holders, a specified number of shares of our common stock, preferred stock, our debt securities or our warrants or any combination of the above at a future date or dates. Alternatively, the purchase contracts may obligate us to purchase from holders, and obligate holders to sell to us, a specific or variable number of shares of our common stock, shares of our preferred stock, our debt securities or our warrants or any combination of the above. The price per share, and number of shares, of our common stock or preferred stock may be fixed at the time the stock purchase contracts are issued or may be determined by reference to a specific formula set forth in the stock purchase contracts. The stock purchase contracts may be issued separately or as a part of units consisting of a stock purchase contract and our debt securities or debt obligations of third parties, including Treasury securities, securing the holders’ obligations to purchase the shares of our common stock under the stock purchase contract, which we refer to as stock purchase units. The stock purchase contracts may require holders to secure their obligations thereunder in a specified manner. The stock purchase contracts also may require us to make periodic payments to the holders of the stock purchase units or vice-versa and such payments may be unsecured or prefunded on some basis.

The applicable prospectus supplement will describe the terms of any stock purchase contracts or stock purchase units. Any description in a prospectus supplement is a summary only and is subject to, and qualified in its entirety by reference to the terms and provisions of the stock purchase contracts, and, if applicable, collateral or depositary arrangements, relating to the stock purchase contracts or stock purchase units, which we will file with the SEC in connection with an issuance of the stock purchase contracts or stock purchase units. Material U.S. federal income tax considerations applicable to the stock purchase units and the stock purchase contracts will also be discussed in the applicable prospectus supplement.

DESCRIPTION OF SUBSCRIPTION RIGHTS

The following is a summary of the general terms of the subscription rights to purchase common stock or other securities that we may offer to stockholders using this prospectus. This summary does not purport to be complete in all respects and is subject to and qualified entirely by reference to the applicable forms of subscription agent agreement and subscription certificate, each of which we will file with the SEC in connection with an offering of any subscription rights.

Subscription rights may be issued independently or together with any other security and may or may not be transferable. As part of any subscription rights offering, we may enter into a standby underwriting or other arrangement under which the underwriters or any other person would purchase any securities that are not purchased in such subscription rights offering. If we issue subscription rights, they will be governed by a separate subscription agent agreement that we will sign with a bank or trust company, as rights agent, that will be named in the applicable prospectus supplement. The rights agent will act solely as our agent and will not assume any obligation to any holders of subscription rights certificates or beneficial owners of subscription rights.

The prospectus supplement relating to any subscription rights we offer will describe the specific terms of the offering and the subscription rights, including the record date for stockholders entitled to the subscription rights distribution, the number of subscription rights issued and the number of shares of common stock or other securities that may be purchased upon exercise of the subscription rights, the exercise price of the subscription rights, the date on which the subscription rights will become effective and the date on which the subscription rights will expire, and any material U.S. federal income tax considerations.

In general, a subscription right entitles the holder to purchase for cash a specific number of shares of common stock or other securities at a specified exercise price. The rights are issued to stockholders as of a specific record date and normally may be exercised only for a limited period of time and become void following the expiration of such period.

If fewer than all of the subscription rights issued in any rights offering are exercised, we may offer any unsubscribed securities directly to persons other than stockholders, to or through agents, underwriters or dealers or through a combination of such methods, including pursuant to standby arrangements, as described in the applicable prospectus supplement. After the close of business on the expiration date of a subscription rights offering, all unexercised subscription rights will become void.

DESCRIPTION OF WARRANTS

We may issue warrants for the purchase of debt securities, preferred stock, common stock, other securities of the Company, or any combination of the foregoing. Warrants may be issued alone or together with securities offered by any prospectus supplement and may be attached to, or separate from, those securities. The particular terms of any warrants will be described more specifically in the prospectus supplement relating to such warrants.

The prospectus supplement relating to any warrants we are offering will include specific terms relating to the offering. We will file the form of any warrant agreement with the SEC, in connection with the offering of any warrants, and you should read the warrant agreement for provisions that may be important to you. We will describe the particular terms of any series of warrants being offered in the applicable prospectus supplement relating to that series of warrants.

Before exercising their warrants, holders of warrants will not have any of the rights of holders of the securities purchasable upon such exercise, including the right to receive dividends, if any, or payments upon our liquidation, dissolution or winding-up, or to exercise voting rights, if any.

DESCRIPTION OF UNITS

As specified in the applicable prospectus supplement, we may issue units consisting of our common stock, debt securities, depositary shares, preferred stock, stock purchase contracts, subscription rights, or warrants or any combination of such securities, including guarantees of any securities. Each series of units will be issued under a separate unit agreement to be entered into between a unit agent and us. The unit agent will act solely as our agent in connection with the units and will not assume any obligation or relationship of agency for or with the holders or beneficial owners of units.

We will issue each unit so that the holder of the unit is also the holder of each security included in the unit. As a result, the holder of a unit will have the rights and obligations of a holder of each security included in such unit. The unit agreement under which a unit is issued may provide that the securities included in the unit may not be held or transferred separately, at any time or at any time before a specified date. A prospectus supplement and any other offering materials relating to any units issued under the registration statement containing this prospectus will specify the terms of the units, including:

The terms and conditions described under “Description of Capital Stock,” “Description of Debt Securities,” “Description of Depositary Shares,” “Description of Stock Purchase Contracts and Stock Purchase Units,” “Description of Subscription Rights,” and “Description of Warrants,” will apply to each unit that includes such securities and to the securities included in each unit, unless otherwise specified in the applicable prospectus supplement.

The applicable prospectus supplement will describe the terms of any units. The preceding description and any description of units in the applicable prospectus supplement does not purport to be complete and is subject to and is qualified in its entirety by reference to the terms of any agreements relating to the units.

PLAN OF DISTRIBUTION

We and any selling security holders may sell the securities offered hereby from time to time in one or more offerings. The applicable prospectus supplement will indicate whether the securities are being offered by us, by selling security holders, or by both, and will describe the applicable plan of distribution.

We and any selling security holders may sell the securities in any one or more of the following ways:

The applicable prospectus supplement will set forth the terms of the offering and the method of distribution and will identify any firms acting as underwriters, dealers or agents in connection with the offering, including:

We may sell securities from time to time to one or more underwriters, who would purchase the securities as principal for resale to the public, either on a firm-commitment or best-efforts basis. Only those underwriters identified in such prospectus supplement will be deemed to be underwriters in connection with the securities offered in the prospectus supplement.

The distribution of the securities may be effected from time to time in one or more transactions at a fixed price or prices, which may be changed, or at prices determined as the applicable prospectus supplement specifies. The securities may be sold through a rights offering, forward contracts or similar arrangements. In connection with the sale of the securities, underwriters, dealers or agents may be deemed to have received compensation from us in the form of underwriting discounts or commissions and also may receive commissions from securities purchasers for whom they may act as agent. Underwriters may sell the securities to or through dealers, and the dealers may receive compensation in the form of discounts, concessions or commissions from the underwriters or commissions from the purchasers for whom they may act as agent. Some of the underwriters, dealers or agents who participate in the securities distribution may engage in other transactions with, and perform other services for, us or our subsidiary in the ordinary course of business.

We will provide in the applicable prospectus supplement information regarding any underwriting discounts or other compensation that we pay to underwriters or agents in connection with the securities offering, and any discounts, concessions or commissions which underwriters allow to dealers. Underwriters, dealers and agents participating in the securities distribution may be deemed to be underwriters, and any discounts and commissions they receive and any profit they realize on the resale of the securities may be deemed to be underwriting discounts and commissions under the Securities Act. Underwriters and their controlling persons, dealers and agents may be entitled, under agreements entered into with us, to indemnification against and contribution toward specific civil liabilities, including liabilities under the Securities Act.

The securities may or may not be listed on a national securities exchange. In connection with an offering, the underwriters may purchase and sell securities in the open market. 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 securities than they are required to purchase in an offering. Stabilizing transactions consist of bids or purchases made for the purpose of preventing or retarding a decline in the market price of the securities while an 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 underwriters have repurchased securities sold by or for the account of that underwriter in stabilizing or short-covering transactions. These activities by the underwriters may stabilize, maintain or otherwise affect the market price of the securities. As a result, the price of the securities 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.

The underwriters, dealers and agents, as well as their associates, may be customers of or lenders to, and may engage in transactions with and perform services for, the Company and its subsidiaries in the ordinary course of business.

Under the securities laws of some states, to the extent applicable, the securities may be sold in such states only through registered or licensed brokers or dealers. In addition, if our common stock is no longer listed on the NASDAQ Global Select Market or another national securities exchange, in some states the securities may not be sold unless such securities have been registered or qualified for sale in such state or an exemption from registration or qualification is available and is complied with.

WHERE YOU CAN FIND MORE INFORMATION

We are subject to the informational requirements of the Exchange Act and file with the SEC proxy statements, Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q and Current Reports on Form 8-K. Our SEC filings are also available to the public from the SEC’s web site at www.sec.gov or on our website at www.ir.mercbank.com. However, other than our available SEC filings, the information on, or that can be accessible through, our website does not constitute a part of, and is not incorporated by reference in, this prospectus.

This prospectus is part of a registration statement on Form S-3 filed by us with the SEC under the Securities Act. As permitted by the SEC, this prospectus does not contain all the information in the registration statement filed with the SEC. For a more complete understanding of this offering, you should refer to the complete registration statement, including exhibits, on Form S-3 that may be obtained as described above. Statements contained in this prospectus about the contents of any contract or other document are not necessarily complete. If we have filed any contract or other document as an exhibit to the registration statement or any other document incorporated by reference in the registration statement, you should read the exhibit for a more complete understanding of the contract or other document or matter involved. Each statement regarding a contract or other document is qualified in its entirety by reference to the actual contract or other document.

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

The SEC allows us to “incorporate by reference” into this prospectus the information we file with it, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is considered to be part of this prospectus, and later information that we file with the SEC will automatically update and supersede this information.

We incorporate by reference into this prospectus the documents listed below and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this prospectus and prior to the termination of this offering as well as any filings after the date of the initial registration statement of which this prospectus forms a part and prior to the effectiveness of such registration statement, but excluding, in each case, information “furnished” rather than “filed” in accordance with SEC rules (unless otherwise indicated therein):

We will provide to each person, including any beneficial owner, to whom a prospectus is delivered, without charge, upon written or oral request, a copy of any or all of the documents that are incorporated by reference into this prospectus and a copy of any or all other contracts or documents which are referred to in this prospectus. Requests should be directed to:

Mercantile Bank Corporation
Attention: Amy Kam, First Vice President, Executive Operations Manager
310 Leonard Street, NW,
Grand Rapids, MI 49504
Telephone: (616) 406-3000

You should rely only on the information incorporated by reference or provided in this prospectus. We have not authorized anyone else to provide you with different information. We are not making an offer of these securities in any state where the offer is not permitted. You should not assume that the information in this prospectus is accurate as of any date other than the date on the front of the document.

LEGAL MATTERS

Certain legal matters in connection with any offering of securities made by this prospectus will be passed upon for us by our counsel Greenberg Traurig, LLP of Phoenix, Arizona. If the securities are being distributed in an underwritten offering, certain legal matters will be passed upon for the underwriters by counsel identified in the related prospectus supplement.

EXPERTS

The consolidated financial statements of Mercantile as of December 31, 2025 and 2024, and the effectiveness of internal control over financial reporting as of December 31, 2025 have been audited by Plante & Moran, PLLC, an independent registered public accounting firm, as set forth in their reports thereon, included in Mercantile’s Annual Report on Form 10-K for the fiscal year ended December 31, 2025, and incorporated herein by reference.

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14. Other Expenses of Issuance and Distribution

The following table sets forth our estimated expenses to be incurred in connection with the issuance and distribution of the securities being registered, other than underwriting discounts and commissions.

Item 15. Indemnification of Directors and Officers

Indemnification

Sections 561-571 of the MBCA, as amended, grant us broad powers to indemnify any person in connection with legal proceedings brought against that person by reason of their present or past status as an officer or director of Mercantile, provided that the person acted in good faith and in a manner he or she reasonably believed to be in or not opposed to Mercantile’s best interests, and with respect to any criminal action or proceeding, had no reasonable cause to believe his or her conduct was unlawful. The MBCA also gives us broad powers to indemnify defined persons against expenses and reasonable settlement payments in connection with any action by or in the right of Mercantile, provided the person acted in good faith and in a manner he or she reasonably believed to be in or not opposed to Mercantile’s best interests, except that no indemnification may be made if that person is adjudged to be liable to us unless and only to the extent the court in which that action was brought determines upon application that, despite the adjudication, but in view of all the circumstances of the case, the person is fairly and reasonably entitled to indemnity for reasonable expenses as the court deems proper. In addition, to the extent that any specified person is successful in the defense of any defined legal proceeding, we are required by the MBCA to indemnify him or her against expenses, including attorneys’ fees that are actually and reasonably incurred in connection with the proceeding.

Our Articles of Incorporation provide that we shall indemnify our present and past directors, officers, and such other persons as the board of directors may authorize to the full extent permitted by law.

Our Bylaws contain indemnification provisions concerning third party actions as well as actions in the right of Mercantile. Our Bylaws provide that we shall indemnify any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative (other than an action by or in the right of Mercantile) by reason of the fact that he or she is or was a director or officer of Mercantile or while serving as such a director or officer, is or was serving at the request of Mercantile as a director, officer, partner, trustee, employee or agent of another foreign or domestic corporation, partnership, joint venture, trust or other enterprise, whether for profit or not, against expenses (including attorney’s fees), judgments, penalties, fees and amounts paid in settlement actually and reasonably incurred by him or her in connection with such action, suit or proceeding if he or she acted in good faith and in a manner he or she reasonably believed to be in or not opposed to the best interests of Mercantile or its shareholders and, with respect to any criminal action or proceeding, had no reasonable cause to believe his or her conduct was unlawful.

Federal Deposit Insurance Corporation regulations impose limitations on indemnification payments which could restrict, in certain circumstances, payments by us or our bank subsidiaries to their respective directors or officers otherwise permitted under the MBCA or the Michigan Banking Code.

With respect to derivative actions, our Bylaws provide that we shall indemnify any person who was or is a party to or is threatened to be made a party to any threatened, pending or completed action or suit by or in the right of Mercantile to procure a judgment in its favor by reason of the fact that he or she is or was a director or officer of Mercantile, or while serving as such a director or officer, is or was serving at the request of Mercantile as a director, officer, partner, trustee, employee or agent of another foreign or domestic corporation, partnership, joint venture, trust or other enterprise, whether for profit or not, against expenses (including attorney’s fees) and amounts paid in settlement actually and reasonably incurred by him or her in connection with the action or suit if he or she acted in good faith and in a manner he or she reasonably believed to be in or not opposed to the best interests of Mercantile or its shareholders. No indemnification is provided in our Bylaws in respect of any claim, issue or matter in which such person has been found liable to Mercantile except to the extent that a court of competent jurisdiction determines upon application that, despite the adjudication of liability but in view of all circumstances of the case, such person is fairly and reasonably entitled to indemnity for such expenses which such court shall deem proper.

Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers and controlling persons of Mercantile pursuant to the provisions discussed above or otherwise, we have been advised that in the opinion of the SEC such indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable.

Insurance

The MBCA permits us to purchase insurance on behalf of our directors and officers against liability arising out of their positions with Mercantile (or positions held with another entity at the request of Mercantile), whether or not the liabilities would be within the indemnification provisions described above.

Our Articles of Incorporation and Bylaws provide that we may purchase and maintain insurance to protect itself and any such director, officer, or other person against any liability arising out of such service to Mercantile, whether or not we have the power to indemnify such person.

Under an insurance policy maintained by us, our directors and officers are insured within the limits and subject to the limitations of the policy, against specified expenses in connection with the defense of specified claims, actions, suits or proceedings, and specified liabilities which might be imposed as a result of claims, actions, suits or proceedings, which may be brought against them by reason of being or having been directors and officers of Mercantile.

Limitation of Director Liability

Section 209(1)(c) of the MBCA permits corporations to limit the personal liability of their directors in certain circumstances. However, under the MBCA, a corporation may not eliminate or limit a director’s liability to the corporation or its shareholders for money damages for any action taken or any failure to take any action as a director for any of the following: (1) the amount of a financial benefit received by a director to which he or she is not entitled; (2) intentional infliction of harm on the corporation or its shareholders; (3) a violation of Section 551 of the MBCA; and (4) an intentional criminal act.

Our Articles of Incorporation provide that our directors shall not be personally liable to us or our shareholders for monetary damages for breach of fiduciary duty, except for liability (1) for any breach of the director’s duty of loyalty to Mercantile or its shareholders; (2) for acts or omissions not in good faith or that involve intentional misconduct or a knowing violation of law; (3) for a violation of Section 551(1) of the MBCA; or (4) for any transaction from which the director derived any improper personal benefit. Under the MBCA, if prior to October 24, 1997 the articles of incorporation of a corporation contained a provision which, subject to exceptions, eliminated liability of a director as Mercantile’s does, that provision is considered to eliminate liability of a director to the extent permitted in Section 209(1)(c) of the MBCA.

Pursuant to our Articles of Incorporation, if the MBCA is amended after the date of our Articles of Incorporation to authorize corporate action eliminating or limiting the personal liability of directors, then the liability of a director of Mercantile shall be eliminated or limited to the fullest extent permitted by the MBCA, as so amended.

Item 16. Exhibits

Item 17. Undertakings

provided, however, that paragraphs (1)(i), (1)(ii) and (1)(iii) do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the SEC by the registrant pursuant to Section 13 or Section 15(d) of the Exchange Act, that are incorporated by reference in this registration statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement.

(b)         Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers and controlling persons of the registrant pursuant to the indemnification provisions described in Item 15 above, or otherwise, the registrant has been advised that in the opinion of the SEC such indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act and will be governed by the final adjudication of such issue.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Grand Rapids, State of Michigan, on this 29th day of September, 2026.

POWER OF ATTORNEY

Each person whose signature appears below constitutes and appoints each of Raymond E. Reitsma and Charles E. Christmas, as his or her true and lawful attorney-in-fact and agent, with full power of substitution and re-substitution, for him or her and in their name, place and stead, in any and all capacities, to sign any and all amendments (including post-effective amendments), and to file the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorney-in-fact and agent, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorney-in-fact and agent, or his substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed by the following persons in the capacities and on the date indicated.

ATTACHMENTS / EXHIBITS

EXHIBIT 5.1

EXHIBIT 23.1

EXHIBIT 107

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