Amendment to Registration Statement - Specified Transactions (Form S-3/A)

As filed with the Securities and Exchange Commission on October 22, 2021

Registration No. 333-260273

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

AMENDMENT NO. 1

TO

FORM S-3

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

CIVISTA BANCSHARES, INC.

(Exact name of registrant as specified in its charter)

100 East Water Street

Sandusky, Ohio 44870

(419) 625-4121

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

Dennis G. Shaffer

President and Chief Executive Officer

Civista Bancshares, Inc.

100 East Water Street

Sandusky, Ohio 44870

(419) 625-4121

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

Copy to:

Anthony D. Weis

Vorys, Sater, Seymour and Pease LLP

52 East Gay Street

Columbus, OH 43215

(614) 464-5465

Approximate date of commencement of proposed sale to the public: From time to time after the effective date of this registration statement.

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, as amended (the "Securities Act"), 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, a smaller reporting company or an emerging growth company. See the definitions of "large accelerated filer," "accelerated filer" "smaller reporting company" and "emerging growth company" in Rule 12b-2 of the Securities Exchange Act of 1934, as amended (the "Exchange Act").

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

CALCULATION OF REGISTRATION FEE

The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act, or until the registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

The information in this prospectus is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED OCTOBER 22, 2021

PROSPECTUS

$100,000,000

Common Shares

Preferred Shares

Depositary Shares

Senior Debt Securities

Subordinated Debt Securities

Warrants

Subscription Rights

Purchase Contracts

Units

Civista Bancshares, Inc. ("Civista," "we," "us," "our" 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.

We may offer and sell up to $100,000,000 in the aggregate of the securities identified above from time to time in one or more offerings. This prospectus provides you with a general description of the securities. When we use the term "securities" in this prospectus, we mean any of the securities we may offer with this prospectus, unless we say otherwise.

Each time we offer and sell securities, we will provide a supplement to this prospectus that contains specific information about the offering and the amounts, prices and terms of the securities. The supplement may also add, update or change information contained in this prospectus with respect to that offering. You should carefully read this prospectus and the applicable prospectus supplement before you invest in any of our securities.

We may offer and sell the securities described in this prospectus and any prospectus supplement to or through one or more underwriters, dealers and agents, or directly to purchasers, or through a combination of these methods. If any underwriters, dealers or agents are involved in the sale of any of the securities, their names and any applicable purchase price, fee, commission or discount arrangement between or among them will be set forth, or will be calculable from the information set forth, in the applicable prospectus supplement. See the sections of this prospectus entitled "ABOUT THIS PROSPECTUS" and "PLAN OF DISTRIBUTION" for more information. No securities may be sold without delivery of this prospectus and the applicable prospectus supplement describing the method and terms of the offering of such securities.

If any securities are to be listed or quoted on a securities exchange or quotation system, our prospectus supplement will say so. Our common shares are listed on The NASDAQ Capital Market under the symbol "CIVB". On October 13, 2021, the last reported sale price of our common shares was $24.62 per share.

These securities are not bank deposits and are not insured by the Federal Deposit Insurance Corporation or any other governmental agency, nor are they obligations of, or guaranteed by, a bank. 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.

INVESTING IN OUR SECURITIES INVOLVES RISKS. YOU SHOULD REVIEW CAREFULLY THE SECTION CAPTONED "RISK FACTORS" ON PAGE 1 OF THIS PROSPECTUS, ANY RISK FACTORS IN ANY APPLICABLE PROSPECTUS SUPPLEMENT, AND UNDER SIMILAR HEADINGS IN THE OTHER DOCUMENTS THAT ARE INCORPORATED BY REFERENCE INTO THIS PROSPECTUS.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.

The date of this prospectus is October 22, 2021.

TABLE OF CONTENTS

i

RISK FACTORS

An investment in our securities involves a high degree of risk. You should carefully consider any risk factors contained in any applicable prospectus supplement, as well as the risk factors set forth in our most recent Annual Report on Form 10-K filed with the United States Securities and Exchange Commission (the "SEC") and any material changes to those risk factors set forth in a Quarterly Report on Form 10-Q. You should also refer to the other information in this prospectus and any applicable prospectus supplement, including our financial statements and the related notes incorporated by reference into this prospectus. Additional risks and uncertainties that are not yet identified may also materially harm our business, operating results and financial condition. If any of these risks actually occur, our business, results of operations and financial condition could suffer. In that case, the trading price of our securities could decline, and you could 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 and adversely from those anticipated in these forward-looking statements as a result of certain factors, including the risks faced by us.

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement on Form S-3 that we have filed with the SEC, using a "shelf" registration process. By using a shelf registration statement, we may sell securities from time to time and in one or more offerings up to a total dollar amount of $100,000,000 (or the equivalent of this amount in foreign currencies or foreign currency units) as described in this prospectus.

Each time that we offer and sell securities, we will provide a prospectus supplement to this prospectus that contains specific information about the securities being offered and sold and the specific terms of that offering. The prospectus supplement as well as any other offering material may also add, update or change information contained in this prospectus with respect to that offering. If there is any inconsistency between the information in this prospectus and the applicable prospectus supplement, you should rely on the prospectus supplement. Before purchasing any securities, you should carefully read this prospectus, the applicable prospectus supplement and any other offering material (including any free writing prospectus), together with the additional information described under the heading "INCORPORATION BY REFERENCE." General information about us, including our Annual Report on Form 10-K, Quarterly Reports on Form 10-Q and Current Reports on Form 8-K, as well as any amendments and exhibits to those reports, are available free of charge through our website at www.civb.com as soon as reasonably practicable after we file them with, or furnish them to, the SEC. Information on our website is not incorporated into this prospectus or our other securities filings and is not a part of these filings.

THIS PROSPECTUS MAY NOT BE USED TO CONSUMMATE A SALE OF SECURITIES UNLESS IT IS ACCOMPANIED BY A PROSPECTUS SUPPLEMENT.

Any of the securities described in this prospectus and in a prospectus supplement may be convertible or exchangeable into, or exercisable for, other securities that are described in this prospectus or will be described in a prospectus supplement, and may be issued separately, together or as part of a unit consisting of two or more securities, which may or may not be separate from one another.

Neither we nor any underwriter has authorized any other person to provide you with any information or to make any representations other than those contained in this prospectus, any applicable prospectus supplement or any free writing prospectus prepared by or on behalf of us or to which we have referred you. We take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. We will not make an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information appearing in this prospectus and the applicable prospectus supplement to this prospectus is accurate as of the date on its respective cover, and that any information incorporated by reference is accurate only as of the date of the document incorporated by reference, unless we indicate otherwise. Our business, financial condition, results of operations and prospects may have changed since those dates.

Our logo and other trademarks or service marks appearing in this prospectus are the property of Civista and our subsidiaries. Solely for convenience, our trademarks and trade names referred to in this prospectus appear without the ^™ symbol, but those references are not intended to indicate, in any way, that we will not assert, to the fullest extent under applicable law, our rights, or the right of the applicable licensor to these trademarks and trade names.

1

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This prospectus, the documents incorporated by reference in this prospectus and any applicable prospectus supplement contain forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended (the "Securities Act"), and Section 21E of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), relating to such matters as financial condition, anticipated operating results, cash flows, business line results, credit quality expectations, prospects for new lines of business, economic trends (including interest rates) and similar matters. Forward-looking statements reflect our expectations, estimates or projections concerning future results or events. These statements are generally identified by the use of forward-looking words or phrases such as "believe," "belief," "expect," "anticipate," "may," "could," "intend," "intent," "estimate," "plan," "foresee," "likely," "will," "should" or other similar words or phrases. Forward-looking statements are not guarantees of performance and are inherently subject to known and unknown risks, uncertainties and assumptions that are difficult to predict and could cause our actual results, performance or achievements to differ materially from those expressed in or implied by the forward-looking statements. Such risks and uncertainties will be described under the "RISK FACTORS" heading of any applicable prospectus supplement and under similar headings in our periodic reports filed with the SEC, which are incorporated by reference in this prospectus, and include, among other factors:

2

The factors identified above should not be considered an exhaustive list of all factors that could adversely affect our business, financial condition, liquidity or results of operations. You should read this prospectus, any applicable prospectus supplements, the documents that we incorporate by reference into this prospectus, the documents that we have included as exhibits to the registration statement of which this prospectus is a part and the documents that we refer to under the sections of this prospectus titled "WHERE YOU CAN FIND MORE INFORMATION" and "INCORPORATION BY REFERENCE" completely and with the understanding that our actual future results could be materially different from what we expect when making the forward-looking statement.

3

We qualify all our forward-looking statements by these cautionary statements. These forward-looking statements speak only as of the date of this prospectus, the date of the document incorporated by reference or the date of any applicable prospectus supplement. Except as required by applicable laws or regulations, we do not undertake any obligation to update or revise any forward-looking statement, whether as a result of new information, future events or otherwise.

The Private Securities Litigation Reform Act of 1995 provides a safe harbor for forward-looking statements, and the purpose of this section is to secure the use of the safe harbor provisions.

CIVISTA BANCSHARES, INC.

Civista, an Ohio corporation incorporated in 1987, is a registered financial holding company headquartered in Sandusky, Ohio. Through Civista Bank, Civista is primarily engaged in the business of community banking, which accounts for substantially all of Civista's revenue, operating income and assets. Civista Bank, an Ohio state chartered bank, conducts a general banking business that involves collecting customer deposits, making loans, purchasing securities and offering trust services. Civista Bank maintains its main office at 100 East Water Street, Sandusky, Ohio and operates branch banking offices in the following Ohio communities: Sandusky (2), Norwalk (2), Berlin Heights, Huron, Port Clinton, Castalia, New Washington, Shelby (2), Willard, Greenwich, Plymouth, Shiloh, Akron, Dublin, Plain City, Russells Point, Urbana (2), West Liberty, Quincy, Dayton (3), Beachwood, and in the following Indiana communities: Lawrenceburg (3), Aurora, West Harrison, Milan, Osgood and Versailles. Civista also operates loan production offices in Westlake, Ohio and Fort Mitchell, Kentucky. In addition to Civista Bank, the Company's other subsidiaries include First Citizens Insurance Agency, Inc., Water Street Properties, Inc., FC Refund Solutions, Inc., First Citizens Investments, Inc., First Citizens Capital LLC, CIVB Risk Management, Inc., First Citizens Statutory Trust II, First Citizens Statutory Trust III, First Citizens Statutory Trust IV, Futura TPF Trust I, and Futura TPF Trust II.

At June 30, 2021, Civista had total assets of approximately $2.9 billion, total deposits of approximately $2.4 billion and total shareholders' equity of approximately $352.4 million.

Our principal executive offices and our mailing address is 100 East Water Street, Sandusky, Ohio 44870, and our telephone number is (419) 625-4121.

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 BY REFERENCE" in this prospectus.

USE OF PROCEEDS

Unless otherwise indicated in any applicable prospectus supplement or other offering materials, we intend to use the net proceeds from the sale of our securities to which this prospectus relates for general corporate purposes. General corporate purposes may include repayment of debt, acquisitions, investments, additions to working capital, and capital expenditures. Additional information on the use of net proceeds from the sale of our securities to which this prospectus relates may be set forth in a prospectus supplement relating to 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.

DESCRIPTION OF SECURITIES WE MAY OFFER

This prospectus contains summary descriptions of the preferred shares, preferred shares, depositary shares, debt securities, warrants, depositary shares, subscription rights, purchase contracts 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. These 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 Second Amended and Restated Articles of Incorporation (our "Articles of Incorporation"), our Amended and Restated Code of Regulations (our "Code of Regulations"), Ohio Corporation Law 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, then the terms described in this prospectus will be deemed superseded by the terms set forth in that prospectus supplement.

4

We may issue securities in book-entry form through one or more depositaries, such as The Depository Trust Company, 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 generally 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 shares as contained in our Articles of Incorporation. This summary does not purport to be a complete description of the terms and conditions of our capital shares in all respects and is subject to and qualified in its entirety by reference to our Articles of Incorporation, our Code of Regulations, each as amended and which are incorporated by reference as an exhibit to the registration statement of which this prospectus is a part, the Ohio General Corporation Law 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 shares set forth in our Articles of Incorporation, it may not contain all of the information that is important to you.

Authorized Capital Stock

Under our Articles of Incorporation, we are authorized to issue up to 40,000,000 common shares and up to 200,000 preferred shares, without par value. As of June 30, 2021, there were 15,434,592 common shares issued and outstanding and no preferred shares issued and outstanding.

Common Shares

Liquidation Rights

Each common share entitles the holder thereof to share ratably in Civista's net assets legally available for distribution to shareholders in the event of Civista's liquidation, dissolution or winding up, after (i) payment in full of all amounts required to be paid to creditors or provision for such payment and (ii) provision for the distribution of any preferential amounts to the holders of any preferred shares that our Board of Directors may designate and issue in the future.

Preemptive Rights

Civista's shareholders do not have preemptive rights. At a special meeting of shareholders on November 4, 2015 (the "2015 Special Meeting"), Civista's shareholders approved and adopted an amendment to Civista's Articles of Incorporation to eliminate pre-emptive rights.

Subscription, Preference, Conversion, Exchange and Redemption Rights

The holders of our common shares do not have subscription, preference, conversion or exchange rights, and there are no mandatory redemption provisions applicable to our common shares. The rights, preferences and privileges of the holders of our common shares are subject to, and may be adversely affected by, the rights, preferences and privileges of holders of any preferred shares that our Board of Directors may designate and issue in the future.

Dividends

As an Ohio corporation, Civista may, in the discretion of our Board of Directors, generally pay dividends to our shareholders out of surplus, however created, but must notify the shareholders if a dividend is paid out of capital surplus. Holders of our common shares are entitled to receive dividends when, as and if declared by our Board of Directors from funds legally available therefor, subject to, and which may be adversely affected by, the rights, preferences and privileges of holders of any preferred shares that our Board of Directors may designate and issue in the future.

Our ability to obtain funds for the payment of dividends and for other cash requirements largely depends on the amount of dividends that may be declared and paid by our subsidiaries. Thus, as a practical matter, any restrictions on the ability of our subsidiaries, including Civista Bank, to pay dividends will act as restrictions on the amount of funds available for payment of dividends by Civista.

5

The ability of Civista Bank to pay dividends is subject to limitations under various laws and regulations and to prudent and sound banking principles. Generally, subject to certain minimum capital requirements, Civista Bank may declare a dividend without the approval of the State of Ohio Division of Financial Institutions so long as the total of the dividends in a calendar year does not exceed Civista Bank's total net income for that year combined with its retained net income for the two preceding years.

We are also subject to policies issued by the Federal Reserve Board that may, in certain circumstances, limit our ability to pay dividends. These policies require, among other things, that we satisfy the capital adequacy regulations applicable to bank holding companies that qualify as financial holding companies, including having a capital conservation buffer that is greater than 2.5%. The Federal Reserve Board may also determine, under certain circumstances relating to our financial condition, that the payment of dividends would be an unsafe or unsound practice and prohibit the payment thereof. Specifically, the Federal Reserve Board has issued a policy statement providing that a financial holding company or other bank holding company should eliminate, defer or significantly reduce dividends if (i) its net income available to holders of our common shares is not sufficient to fully fund the dividends, (ii) the prospective rate of earnings retention is not consistent with the financial or bank holding company's capital needs and overall financial condition or (iii) the financial or bank holding company will not meet or is in danger of not meeting its required regulatory capital adequacy ratios. In addition, the Federal Reserve Board expects us to serve as a source of strength to Civista Bank, which may require us to retain capital for further investments in Civista Bank, rather than use those funds for dividends for our shareholders.

The ability of our subsidiaries to pay dividends to us is also subject to their profitability, financial condition, capital expenditures and other cash flow requirements and contractual obligations.

Voting Rights

Each of our common shares entitles the holder thereof to one vote on each matter submitted to the Civista shareholders for consideration. At the 2015 Special Meeting, Civista's shareholders approved and adopted an amendment to Civista's Articles of Incorporation to eliminate cumulative voting in the election of directors.

Our Articles of Incorporation contain special voting requirements in connection with the approval or authorization of certain types of business combinations, as further described below under "Anti-Takeover Effects of Our Articles of Incorporation, Code of Regulations and Applicable Laws."

Number and Term of Directors

Our Code of Regulations provides for our Board of Directors to consist of not less than five and not more than 25 directors. Members of the Board of Directors are elected each year at the annual meeting of shareholders to a one-year term.

Removal of Directors

Under our Code of Regulations, any director or the entire Board of Directors may be removed with or without cause by the affirmative vote of a majority of the shares then entitled to vote at the election of directors. Notwithstanding the foregoing, if, in the event of any proposed business combination transaction, as defined in Article EIGHTH of our Articles of Incorporation, the affirmative vote of eighty percent (80%) shall be required to remove any or the entire Board of Directors.

Nomination of Directors

Nominations of persons for election to the Board of Directors at a meeting of shareholders may be made by or at the direction of the Board of Directors or may be made at a meeting of shareholders by any shareholder of Civista entitled to vote for the election of directors at the meeting who complies with the notice procedures set forth in our Code of Regulations. Such nominations, other than those made by or at the direction of the Board of Directors, must be made pursuant to timely notice in writing to the Secretary of Civista. To be timely, a shareholder's notice must be delivered to or mailed and received at the principal executive offices of Civista not less than 14 days nor more than 50 days prior to the meeting; provided, however, that in the event that less than 21 days' notice or prior public disclosure of the date of the meeting is given or made to shareholders, notice by the shareholder to be timely must be so delivered or mailed no later than the close of business on the 7th day following the day on which notice of the date of the meeting was mailed or such public disclosure was made, whichever first occurs, but in no event shall such timely notice of shareholder nomination be received by the Secretary of Civista less than seven (7) days prior to the shareholder meeting.

6

A shareholder's notice to the Secretary must set forth (a) as to each person whom the shareholder proposed to nominate for the election or re-election as a director, (i) the name, age, business address and residence address of the person, (ii) the principal occupation or employment of the person, and (iii) the class and number of shares of capital stock of Civista which are beneficially owned by the person; and (b) as to the shareholder giving the notice (i) the name and record address of the shareholder and (ii) the class and number of shares of capital stock of Civista which are beneficially owned by the shareholder. Civista may require any proposed nominee to furnish such other information as may reasonably be required by Civista to determine the eligibility of such proposed nominee to serve as a director of Civista.

Listing

Our common shares are listed on The NASDAQ Capital Market under the symbol "CIVB."

Transfer Agent and Registrar

The transfer agent and registrar for our common shares is American Stock Transfer & Trust Company, LLC.

Preferred Shares

Our 200,000 authorized but unissued preferred shares are typically referred to as "blank check" preferred shares. This term refers to preferred shares for which the rights and restrictions are determined by the board of directors of a corporation at the time the preferred shares are issued. Under our Articles of Incorporation, our Board of Directors has the authority, without any further shareholder vote or action, to issue preferred shares in one or more series, from time to time, and, in connection with the creation of any such series, to adopt an amendment or amendments to our Articles of Incorporation determining, in whole or in part, the express terms of any such series to the fullest extent permitted under Ohio law, including, but not limited to, determining: the division of such shares into series and the designation and authorized number of shares of each series; dividend or distribution rights; dividend rate; liquidation rights, preferences and price; redemption rights and price; sinking fund requirements; voting rights; pre-emptive rights; conversion rights; restrictions on the issuance of shares; and other relative, participating, optional or other special rights and privileges of each such series and the qualifications, limitations or restrictions thereof. Notwithstanding the foregoing, in no event may the voting rights of any series of preferred shares be greater than the voting rights of the common shares.

Anti-Takeover Effects of Our Articles of Incorporation, Code of Regulations and Ohio Laws

Certain provisions in our Articles of Incorporation, Code of Regulations and applicable laws could discourage potential takeover attempts and make attempts by shareholders to change management more difficult. These provisions could adversely affect the market price of our shares.

Special Voting Requirements

Article SIXTH of the Articles of Incorporation sets forth certain requirements in connection with the approval or authorization of any of the following types of business combinations:

7

For purposes of Article SIXTH, "related person" generally means any person, entity or group, including any affiliate or associate thereof (other than Civista, any wholly-owned subsidiary of Civista, or any trustee of, or fiduciary with respect to, any plan when acting in such capacity) that, at the time any business combination is agreed to, authorized or approved, is the beneficial owner of not less than 10% of the common shares entitled to vote on such business combination.

Article SIXTH provides that, when evaluating a business combination or any tender or exchange offer, our Board of Directors shall consider, without limitation: (i) the social and economic effects of the transaction on Civista and its subsidiaries, employees, customers, creditors and community; (ii) the business and financial conditions and earning prospects of the acquiring person or persons; and (iii) the competence, experience and integrity of the acquiring person or persons and its or their management.

Article SIXTH further provides that the affirmative vote of the holders of not less than 80% of each class of common shares entitled to vote on the transaction shall be required for the approval of any business combination in which a related person has an interest (except proportionately as a shareholder); provided, however, that the 80% voting requirement shall not be applicable if (a) the continuing directors, who at the time constitute at least a majority of our Board of Directors, have approved the business combination by at least two-thirds vote or (b) certain conditions relating to the fairness of the transaction have been satisfied. If the 80% voting requirement is inapplicable, any business combination requiring shareholder approval may be authorized by the affirmative vote of the holders of common shares entitling them to exercise a majority of the voting power of Civista in accordance with Article FIFTH of the Articles of Incorporation.

Article SEVENTH of the Articles of Incorporation provides that no amendment of the Articles of Incorporation shall be effective to amend, alter or repeal any of the provisions of Article SIXTH unless such amendment shall receive the affirmative vote of the holders of not less than 80% of the common shares entitled to vote thereon; provided, however, that the 80% voting requirement shall not be applicable if such amendment shall have been proposed and authorized by our Board of Directors by the affirmative vote of at least two-thirds of the continuing directors.

Limited Shareholder Action by Written Consent

The Ohio Revised Code requires that an action by written consent of the shareholders in lieu of a meeting be unanimous, except that the code of regulations may be amended by an action by written consent of holders of shares entitling them to exercise two-thirds of the voting power of the corporation or, if the articles of incorporation or code of regulations otherwise provide, such greater or lesser amount, but not less than a majority. This provision may have the effect of delaying, deferring or preventing a tender offer or takeover attempt that a shareholder might consider to be in its best interest.

Ohio Control Share Acquisition Act

Section 1701.831 of the Ohio Revised Code provides that certain notice and informational filings, and special shareholder meeting and voting procedures, must occur prior to any person's acquisition of an issuer's shares that would entitle the acquirer to exercise or direct the voting power of the issuer in the election of directors within any of the following ranges:

The Control Share Acquisition Act does not apply to a corporation if its articles of incorporation or code of regulations so provide. We have not opted out of the application of the Control Share Acquisition Act.

8

Ohio Merger Moratorium Statute

Chapter 1704 of the Ohio Revised Code generally addresses a wide range of business combinations and other transactions (including mergers, consolidations, asset sales, loans, disproportionate distributions of property and disproportionate issuances or transfers of shares or rights to acquire shares) between an Ohio corporation and an "Interested Shareholder" who, alone or with others, may exercise or direct the exercise of at least 10% of the voting power of the corporation in the election of directors. The Merger Moratorium Statute prohibits such transactions between the corporation and the Interested Shareholder for a period of three years after a person becomes an Interested Shareholder, unless, prior to such date, the directors approved either the business combination or other transaction or approved the acquisition that caused the person to become an Interested Shareholder.

Following the three-year moratorium period, the corporation may engage in the covered transaction with the Interested Shareholder if:

The Merger Moratorium Statute does not apply to a corporation if its articles of incorporation or code of regulations so provide. We have not opted out of the application of the Merger Moratorium Statute.

Ohio Anti-Greenmail Statute

Pursuant to the Ohio Anti-Greenmail Statute (Section 1707.043 of the Ohio Revised Code), a public corporation formed in Ohio may recover profits that a shareholder makes from the sale of the corporation's securities within 18 months after making a proposal to acquire control or publicly disclosing the possibility of a proposal to acquire control. The corporation may not, however, recover from a person who proves either: (1) that his sole purpose in making the proposal was to succeed in acquiring control of the corporation and there were reasonable grounds to believe that he would acquire control of the corporation; or (2) that his purpose was not to increase any profit or decrease any loss in the shares. Also, before the corporation may obtain any recovery, the aggregate amount of the profit realized by such person must exceed $250,000. Any shareholder may bring an action on behalf of the corporation if a corporation refuses to bring an action to recover these profits. The party bringing such an action may recover his attorneys' fees if the court having jurisdiction over such action orders recovery of any profits.

The Anti-Greenmail Statute does not apply to a corporation if its articles of incorporation or code of regulations so provide. We have not opted out of the application of the Anti-Greenmail Statute.

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, including a "financial holding company", to obtain the approval of the Federal Reserve prior to acquiring more than 5% of the outstanding shares of a class of our voting shares. Any person other than a financial or 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 shares under the Change in Bank Control Act of 1978. Any holder of 25% or more (or between 10% and 25%, if the holder is unable to rebut the presumption that it controls the Company) of the outstanding shares of a class of our voting shares, other than an individual, is subject to supervision and regulation as a bank holding company under the BHCA. In calculating a holder's aggregate ownership of our common shares for purposes of these banking regulations, the Federal Reserve likely would include at least the minimum number of shares (and could instead include the maximum number of shares) of our common shares that a holder is entitled to receive pursuant to securities convertible into or settled in our common shares.

Ohio Revised Code Section 1115.06 provides change-of-control requirements that prohibit any person, acting directly or indirectly or in concert with one or more persons, from acquiring control of Civista or Civista Bank unless such person has given the Ohio Superintendent of Financial Institutions 60 days' prior written notice and the Superintendent has not disapproved the acquisition. "Control", as defined in Section 1115.06, means the power, directly or indirectly, to direct the management or policies of a state bank or bank holding company or to vote 25% or more of any class of voting securities of a state bank or bank holding company.

9

Additionally, it is presumed, subject to rebuttal, that a person controls an Ohio bank or bank holding company if the person owns or has the power to vote 10% or more of any class of voting securities and either the bank or bank holding company has a class of securities registered under Section 12 of the Exchange Act or no other person owns or has the power to vote a greater percentage of that class of voting securities.

DESCRIPTION OF DEPOSITARY SHARES

This section describes the general terms of the depositary shares we may offer and sell by this prospectus. This prospectus and any accompanying prospectus supplement will contain the material terms and conditions for the depositary shares. The accompanying prospectus supplement may add, update, or change the terms and conditions of the depositary shares as described in this prospectus. As used in this "Description of Depositary Shares" the terms "we", "our," and "us" refer only to Civista Bancshares, Inc. and not, unless otherwise indicated, any of our subsidiaries.

General

We may, at our option, elect to offer fractional preferred shares, rather than full preferred shares. If we exercise this option, we will issue depositary receipts for depositary shares, each of which will represent a fractional interest of a share of a particular series of preferred shares, as specified in the applicable prospectus supplement. We will deposit with a depositary (the "preferred stock depositary") preferred shares of each series represented by depositary shares and enter into a deposit agreement with the preferred stock depositary and record holders from time to time of the depositary receipts issued by the preferred stock depositary which evidence the depositary shares. Subject to the terms of the deposit agreement, each record holder of a depositary receipt will be entitled, in proportion to the record holder's fractional interest in the preferred shares, to all the rights and preferences of the series of the preferred shares represented by the depositary shares (including dividend, voting, conversion, redemption and liquidation rights). The depositary shares will be evidenced by depositary receipts issued pursuant to the deposit agreement. Depositary receipts will be issued to those persons purchasing the fractional preferred shares in accordance with the terms of the deposit agreement as described in the applicable prospectus supplement.

Dividends and Other Distributions

The preferred stock depositary will distribute all cash dividends or other cash distributions received in respect of the preferred shares underlying the depositary shares to the record holders of depositary receipts in proportion to the number of the depositary receipts owned by the record holders. The relevant record date for depositary shares will be the same date as the record date for the preferred shares.

In the event of a distribution other than in cash, the preferred stock depositary will distribute property received by the preferred stock depositary to the record holders of depositary receipts in proportion to the number of the depositary receipts owned by the record holders. If the preferred stock depositary determines that it is not feasible to make such distribution, the preferred stock depositary may, with our approval, adopt another method of distribution, including selling the property and distributing the net proceeds from the sale to the record holders.

If we offer to the holders of a series of preferred shares represented by the depositary shares any rights, preferences or privileges to subscribe for or purchase any securities, or any other rights, preferences or privileges, the preferred stock depositary will make such rights, preferences or privileges available to the record holders of depositary receipts either by the issue of warrants representing such rights, preferences or privileges or by such other method as approved by the preferred stock depositary and us. If the preferred stock depositary determines that such action is not lawful or feasible or if it is instructed by a record holder of depositary receipts that such record holder does not want to exercise such rights, preferences or privileges, the preferred stock depositary may (with our approval in any case when the preferred stock depositary has determined that it is not feasible to make such rights, preferences or privileges available) sell such rights, preferences or privileges and distribute the net proceeds from such sale to the record holders of depositary receipts entitled to such proceeds.

10

Withdrawal of Shares

Preferred shares represented by depositary shares may be withdrawn from the depositary arrangement upon surrender of depositary receipts at the principal office of the preferred stock depositary and upon payment of the taxes, charges and fees provided for in the deposit agreement. Subject to the terms of the deposit agreement, the record holder of depositary receipts will receive the appropriate number of preferred shares and any money or property represented by the related depositary shares. Only whole preferred shares may be withdrawn; if a record holder of depositary receipts holds an amount of depositary shares in excess of whole preferred shares, the preferred stock depositary will deliver along with the withdrawn preferred shares a new depositary receipt evidencing the excess number of depositary shares. Except as described in the deposit agreement, holders of withdrawn preferred shares will not be entitled to redeposit such preferred shares or to receive depositary shares for such preferred shares.

Redemption

If we redeem preferred shares held by the preferred stock depositary, the preferred stock depositary will concurrently redeem the number of depositary shares representing the preferred shares so redeemed (provided that we have paid the applicable redemption price for the preferred shares to be redeemed plus an amount equal to any accrued and unpaid dividends to the date fixed for redemption). The redemption price per depositary share will be equal to the redemption price and any other amounts payable per share on the preferred shares multiplied by the fraction of a preferred share represented by one depositary share. If fewer than all the outstanding depositary shares are to be redeemed, the depositary shares to be redeemed will be selected by lot or pro rata (as nearly as may be practicable without creating fractional depositary shares) or as otherwise determined by us.

After the date fixed for redemption, depositary shares called for redemption will no longer be deemed to be outstanding and all rights of the record holders of depositary receipts evidencing depositary shares will cease, except the right to receive, upon surrender to the preferred stock depositary of the depositary receipts evidencing the depositary shares, the monies payable upon redemption and any money or other property to which the record holders of the depositary receipts were entitled upon redemption.

Voting

Upon receipt of notice of any meeting at which the holders of the preferred shares are entitled to vote, the preferred stock depositary will mail the information contained in the notice of meeting to the record holders of the depositary receipts. Each record holder of the depositary receipts on the record date (which will be the same date as the record date for the preferred shares) will be entitled to instruct the preferred stock depositary as to the exercise of the voting rights pertaining to the amount of preferred shares represented by the depositary shares evidenced by the record holder's depositary receipts. The preferred stock depositary will vote the amount of preferred shares represented by the depositary shares in accordance with the record holder's instructions, and we will agree to take all reasonable action necessary to enable the preferred stock depositary to vote such preferred shares. The preferred stock depositary will abstain from voting the amount of preferred shares represented by the depositary shares for which it does not receive specific instructions from the record holders of depositary receipts evidencing the depositary shares.

Liquidation Preference

If we voluntarily or involuntarily liquidate, dissolve or wind up, the record holders of depositary receipts will be entitled to the fraction of the liquidation preference accorded each preferred share represented by the depositary shares evidenced by such depositary receipts, as set forth in the applicable prospectus supplement.

Adjustments

Upon any change in par value or liquidation preference, split-up, combination or any other reclassification of the series of preferred shares represented by the depositary shares, or upon recapitalization, reorganization, merger or consolidation affecting us or to which we are a party, the preferred stock depositary may in its discretion, with our approval (not to be unreasonably withheld) and instructions, and in such manner as the preferred stock depositary may deem equitable, treat any securities which are received by the preferred stock depositary in exchange for or upon conversion or in respect of such preferred shares as new deposited securities received in exchange for or upon conversion or in respect of such preferred shares and may make such adjustments in the fraction of an interest represented by one depositary share in one such preferred share as may be necessary to fully reflect the effects of such change. With our approval, the preferred stock depositary may execute and deliver additional depositary receipts, or may call for the surrender of all outstanding depositary receipts to be exchanged for new depositary receipts specifically describing such new deposited securities.

11

Amendment

We may amend the form of depositary receipt and any provision of the deposit agreement at any time by agreement between us and the preferred stock depositary. However, any amendment that materially and adversely alters the rights of the record holders of depositary receipts or that would be materially and adversely inconsistent with the rights granted to the holders of the related preferred shares will not be effective unless the record holders of at least two-thirds of the depositary shares evidenced by the depositary receipts then outstanding approve the amendment. No amendment will impair the right, subject to the exceptions set forth in the deposit agreement, of any record holder of depositary receipts to surrender any depositary receipt with instructions to deliver to the record holder the related preferred shares and all money and other property, if any, represented by the depositary receipt, except in order to comply with law. Every record holder of an outstanding depositary receipt at the time any such amendment becomes effective will be deemed, by continuing to hold the depositary receipt, to consent and agree to the amendment and to be bound by the deposit agreement as amended.

Termination

We may terminate the deposit agreement upon not less than 30 days' prior written notice to the preferred stock depositary if a majority of each series of preferred shares affected by the termination consents to the termination. Upon termination, the preferred stock depositary will deliver or make available to each record holder of depositary receipts, upon surrender of the depositary receipts held by the record holder, the number of whole and/or fractional preferred shares represented by the depositary shares evidenced by the depositary receipts together with any other property held by the preferred stock depositary with respect to the depositary receipts.

In addition, the deposit agreement will automatically terminate if:

Charges of Preferred Stock Depositary

We will pay all transfer and other taxes and governmental charges arising solely from the existence of the deposit agreement. In addition, we will pay the fees and charges of the preferred stock depositary in connection with the initial deposit of the preferred shares, the initial issuance of the depositary shares, any redemption of the preferred shares and all withdrawals of preferred shares by record holders of depositary receipts evidencing depositary shares. All other transfer, income and other taxes and governmental charges will be at the expense of the record holders of depositary receipts. Record holders of depositary receipts will also pay such other charges and expenses (a) as are expressly provided in the deposit agreement to be for their accounts and (b) for any duties requested by the record holders of depositary receipts to be performed which are outside of those expressly provided for in the deposit agreement. If those charges, expenses and taxes have not been paid by the holders of depositary receipts, the preferred stock depositary may refuse to transfer depositary shares or withdraw any preferred shares, withhold dividends and distributions and sell the preferred shares or other property represented by the depositary shares evidenced by the depositary receipts.

Resignation and Removal of Preferred Stock Depositary

The preferred stock depositary may resign at any time by delivering to us notice of its election to resign, and we may at any time remove the preferred stock depositary. Any such resignation or removal will take effect upon our appointment of a successor preferred stock depositary and its acceptance of such appointment. We must appoint a successor preferred stock depositary within 60 days after delivery of the notice of resignation or removal, and any preferred stock depositary must be a bank or trust company having its principal office in the United States and having the requisite combined capital and surplus as set forth in the applicable agreement.

12

Notices

The preferred stock depositary will forward to record holders of depositary receipts any notice, reports and other communications that are delivered to the preferred stock depositary and that we are required to furnish to the holders of the preferred shares. In addition, the preferred stock depositary will make available for inspection by record holders of depositary receipts at the principal office of the preferred stock depositary, and at such other places as it may from time to time deem advisable, any reports and communications we deliver to the preferred stock depositary as the holder of preferred shares.

Limitation of Liability

We will not be liable, nor will the preferred stock depositary be liable, if we or the preferred stock depositary is prevented from or delayed, by law or any circumstances beyond our control, in performing our and such preferred stock depositary's respective obligations under the deposit agreement. Our obligations and the obligations of the preferred stock depositary under the deposit agreement will be limited to performing our duties in good faith and without negligence (only in the case of any action or inaction in the voting of preferred shares represented by the depositary shares), gross negligence or willful misconduct. We will not be obligated, nor will the preferred stock depositary be obligated, to prosecute or defend any legal proceeding in respect of any depositary receipts, depositary shares or preferred shares represented by depositary shares unless satisfactory indemnity is furnished. We may rely, and the preferred stock depositary may rely, on written advice of counsel or accountants, or information provided by record holders of depositary receipts or other persons believed in good faith to be competent to give such information, and on documents reasonably believed to be genuine and signed or presented by a proper party.

DESCRIPTION OF DEBT SECURITIES

We may offer from time to time debt securities in the form of either senior debt securities or subordinated debt securities. Unless otherwise specified in a supplement to this prospectus, the debt securities will be our direct, unsecured obligations and will rank equally with all of our other unsecured and unsubordinated indebtedness. The debt securities will be issued under one or more separate indentures between us and a trustee to be identified in the applicable indenture. Prior to issuing any debt securities under either indenture, we will select the trustee for the indenture relating to the issuance of such securities, qualify the trustee under the Trust Indenture Act of 1939, as amended, and execute such indenture.

Forms of indenture for senior indebtedness and subordinated indebtedness have been included as exhibits to the registration statement of which this prospectus is a part. We have summarized the general terms and provisions of these indentures below, which are substantially identical between the two indentures except for the subordination provisions described below under "Subordinated Debt Securities" in this "Description of Debt Securities". The following summary of the terms of the indentures is subject to, and qualified in its entirety by reference to, the indentures, which contain the full legal text of the matters described in this section. You should read the indentures for provisions that may be important to you.

When we offer to sell a particular series of debt securities, we will describe the specific terms of the series in a supplement to this prospectus. We will also indicate in the supplement whether the general terms and provisions described in this prospectus apply to a particular series of debt securities. Capitalized terms used in this "Description of Debt Securities" and not defined herein have the meanings specified in the forms of indenture. This summary refers to both indentures as the form of "indenture".

Since we are a holding company, our right, and accordingly, the right of our creditors and shareholders, including the holders of the securities offered by this prospectus and any prospectus supplement, to participate in any distribution of assets of any of our subsidiaries upon that subsidiary's liquidation, reorganization or similar proceeding is subject to the prior claims of creditors of that subsidiary, except to the extent that our claims as a creditor of the subsidiary may be recognized.

As used in this "Description of Debt Securities," the terms "we", "our," and "us" refer only to Civista Bancshares, Inc. and not, unless otherwise indicated, any of our subsidiaries.

General

Each indenture gives us broad authority to establish the particular terms of each series of debt securities, including the right to modify certain of the terms contained in the indenture with respect to that series of debt securities. In the prospectus supplement relating to a series of debt securities, we will describe the specific terms of such series of debt securities and the extent, if any, to which the specific terms of that series of debt securities modify the terms of the applicable indenture.

13

We can issue an unlimited amount of debt securities under each of the indentures. The debt securities may be in one or more series with the same or various maturities, at par, at a premium, or at a discount. All of the debt securities issued under each of the indentures will rank equally and ratably with any additional debt securities issued under the same indenture.

Prior to the issuance of each series of debt securities, the terms of such series of debt securities will be established by or pursuant to a resolution of our Board of Directors and set forth or determined in the manner provided in a supplemental indenture. We will describe in the applicable prospectus supplement the particular terms of the debt securities being offered, including the following, as may be applicable:

14

We may issue debt securities that provide for an amount less than their stated principal amount to be due and payable upon declaration of acceleration of their maturity pursuant to the terms of the indenture with respect to the debt securities. We will provide you with information on the federal income tax considerations and other special considerations applicable to any of the debt securities in the applicable prospectus supplement.

Transfer and Exchange

Each debt security will be represented by either one or more global securities registered in the name of The Depositary Trust Company, as Depositary, or a nominee (we will refer to any debt security represented by a global debt security as a "book-entry debt security"), or a certificate issued in definitive registered form (we will refer to any debt security represented by a certificated security as a "certificated debt security") as set forth in the applicable prospectus supplement. Except as set forth under the heading "Global Debt Securities and Book-Entry System" below, book-entry debt securities will not be issuable in certificated form.

Certificated Debt Securities

You may transfer or exchange certificated debt securities at any office we maintain for this purpose in accordance with the terms of the indenture with respect to the debt securities. No service charge will be made for any transfer or exchange of certificated debt securities, but we may require payment of a sum sufficient to cover any tax or other governmental charge payable in connection with a transfer or exchange.

You may effect the transfer of certificated debt securities and the right to receive the principal of and interest on certificated debt securities only by surrendering the certificate representing those certificated debt securities and either reissuance by us or the trustee of the certificate to the new holder or the issuance by us or the trustee of a new certificate to the new holder.

Global Debt Securities and Book-Entry System

Each global debt security representing book-entry debt securities will be deposited with, or on behalf of, the Depositary, and registered in the name of the Depositary or a nominee of the Depositary. The Depositary has indicated it intends to follow the following procedures with respect to book-entry debt securities.

Ownership of beneficial interests in book-entry debt securities will be limited to persons that have accounts with the Depositary for the related global debt security, which we refer to as participants, or persons that may hold interests through participants. Upon the issuance of a global debt security, the Depositary will credit, on its book-entry registration and transfer system, the participants' accounts with the respective principal amounts of the book-entry debt securities represented by such global debt security beneficially owned by such participants. The accounts to be credited will be designated by any dealers, underwriters or agents participating in the distribution of the book-entry debt securities. Ownership of book-entry debt securities will be shown on, and the transfer of such ownership interests will be effected only through, records maintained by the Depositary for the related global debt security (with respect to interests of participants) and on the records of participants (with respect to interests of persons holding through participants). The laws of some states may require that certain purchasers of securities take physical delivery of such securities in definitive form. These laws may impair the ability to own, transfer or pledge beneficial interests in book-entry debt securities.

15

So long as the Depositary for a global debt security, or its nominee, is the registered owner of that global debt security, the Depositary or its nominee, as the case may be, will be considered the sole owner or holder of the book-entry debt securities represented by such global debt security for all purposes under the indenture with respect to the debt securities. Except as described below, beneficial owners of book-entry debt securities will not be entitled to have securities registered in their names, will not receive or be entitled to receive physical delivery of a certificate in definitive form representing securities and will not be considered the owners or holders of those securities under the indenture with respect to the debt securities. Accordingly, each person beneficially owning book-entry debt securities must rely on the procedures of the Depositary for the related global debt security and, if such person is not a participant, on the procedures of the participant through which such person owns its interest, to exercise any rights of a holder under the applicable indenture.

We understand, however, that under existing industry practice, the Depositary will authorize the persons on whose behalf it holds a global debt security to exercise certain rights of holders of debt securities, and the indenture with respect to the debt securities provides that we, the trustee and our respective agents will treat as the holder of a debt security the persons specified in a written statement of the Depositary with respect to that global debt security for purposes of obtaining any consents or directions required to be given by holders of the debt securities pursuant to the applicable indenture.

We will make payments of principal of, and premium and interest on, book-entry debt securities to the Depositary or its nominee, as the case may be, as the registered holder of the related global debt security. Civista, the trustee and any other agent of ours or agent of the trustee will not have any responsibility or liability for any aspect of the records relating to or payments made on account of beneficial ownership interests in a global debt security or for maintaining, supervising or reviewing any records relating to beneficial ownership interests.

We expect that the Depositary, upon receipt of any payment of principal of, or premium or interest on, a global debt security, will immediately credit participants' accounts with payments in amounts proportionate to the respective amounts of book-entry debt securities held by each participant as shown on the records of the Depositary. We also expect that payments by participants to owners of beneficial interests in book-entry debt securities held through those participants will be governed by standing customer instructions and customary practices, as is now the case with the securities held for the accounts of customers in bearer form or registered in "street name", and will be the responsibility of those participants.

We will issue certificated debt securities in exchange for each global debt security if the Depositary is at any time unwilling or unable to continue as Depositary or ceases to be a clearing agency registered under the Exchange Act, and a successor Depositary registered as a clearing agency under the Exchange Act is not appointed by us within 90 days. In addition, we may at any time and in our sole discretion determine not to have the book-entry debt securities of any series represented by one or more global debt securities and, in that event, will issue certificated debt securities in exchange for the global debt securities of that series. Global debt securities will also be exchangeable by the holders for certificated debt securities if an event of default with respect to the book-entry debt securities represented by those global debt securities has occurred and is continuing. Any certificated debt securities issued in exchange for a global debt security will be registered in such name or names as the Depositary shall instruct the trustee. We expect that such instructions will be based upon directions received by the Depositary from participants with respect to ownership of book-entry debt securities relating to such global debt security.

We have obtained the foregoing information concerning the Depositary and the Depositary's book-entry system from sources we believe to be reliable, but we take no responsibility for the accuracy of this information.

No Protection in the Event of a Change of Control

Unless we state otherwise in the applicable prospectus supplement, the debt securities will not contain any provisions which may afford holders of the debt securities protection, such as acceleration, in the event we have a change in control or in the event of a highly leveraged transaction (whether or not such transaction results in a change in control), which could adversely affect holders of debt securities.

Covenants

Unless otherwise stated in the applicable prospectus supplement, the covenants described below apply to any and all series of debt securities. We will describe any additional covenants for a particular series of debt securities in the applicable prospectus supplement.

16

Payment of Principal and Interest

We, for the benefit of the holders of each series of debt securities, will agree to duly and punctually pay or cause to be paid the principal of and interest, if any, on the debt securities of that series in accordance with the terms of such debt securities and the applicable indenture.

SEC Reports

We will deliver to the trustee copies of annual reports and information, documents and other reports required to be filed with the SEC under Section 13 or Section 15(d) of the Exchange Act, within 15 days after such documents are filed with the SEC.

Compliance Certificate

We will deliver to the trustee, within 120 days after the end of each fiscal year occurring after the first date any series of debt securities issued under the applicable indenture is outstanding, an officers' certificate stating whether or not, to the best of such officers' knowledge after a review of the activities of Civista and our subsidiaries during the preceding fiscal year, we have kept, observed, performed and fulfilled the covenants in the applicable indenture and are not in default in the performance or observance of any of the terms, provisions and conditions of the applicable indenture and, if we are in default, specifying all such defaults and the nature and status of such defaults as to which such person has knowledge.

Stay, Extension and Usury Laws

We will not at any time insist upon, pledge or in any manner claim or take the benefit of advantage of, any stay, extension or usury law affecting the covenants or performance of the applicable indenture or the debt securities issued thereunder.

Corporate Existence

Subject to Article V of each indenture ("Successors"), we will do or cause to be done all things necessary to preserve and keep in full force and effect our corporate existence and our rights (charter and statutory), licenses and franchises; provided, however, that we will not be required to preserve any such right, license or franchise if our Board of Directors determines that the preservation of such right, license or franchise is no longer desirable in the conduct of the collective business of us and our subsidiaries, taken as a whole, and that the loss thereof will not be adverse to the holders of the debt securities in any material respect.

Taxes

We will pay, prior to delinquency, all taxes, assessments and governmental levies, except as contested in good faith and by appropriate proceedings.

Consolidation, Merger and Sale of Assets

We may not consolidate with or merge with or into, or convey, transfer or lease all or substantially all of our properties and assets to, any person, which we refer to as a successor person, unless:

17

Events of Default

Event of default means, with respect to any series of debt securities, any of the following:

No event of default with respect to a particular series of debt securities (except as to certain events of bankruptcy, insolvency or reorganization) necessarily constitutes an event of default with respect to any other series of debt securities. In addition, the occurrence of certain events of default or an acceleration under the indenture with respect to the debt securities may constitute an event of default under certain of our other indebtedness outstanding from time to time.

The holders of a majority in principal amount of the outstanding debt securities of any series may on behalf of the holders of all the debt securities of such series waive any past default under the applicable indenture with respect to that series and its consequences, except a default in the payment of the principal of or any interest on any debt security of that series or in respect of a covenant or provision, which cannot be modified or amended without the consent of the holder of each outstanding debt security of the series affected;provided, however, that the holders of a majority in principal amount of the outstanding debt securities of any series may rescind an acceleration and its consequences, including any related payment default that resulted from the acceleration.

Acceleration of Maturity; Rescission and Annulment

If an event of default with respect to debt securities of any series at the time outstanding occurs and is continuing, then the trustee or the holders of not less than a majority in principal amount of the outstanding debt securities of that series may, by a notice in writing to us (and to the trustee if given by the holders), declare to be due and payable immediately the principal (or, if the debt securities of that series are discount securities, that portion of the principal amount as may be specified in the terms of that series) of and accrued and unpaid interest, if any, on all debt securities of that series. In the case of an event of default resulting from certain events of bankruptcy, insolvency or reorganization, the principal (or such specified amount) of and accrued and unpaid interest, if any, on all outstanding debt securities will become and be immediately due and payable without any declaration or other act on the part of the trustee or any holder of outstanding debt securities. Any payment by us on subordinated debt securities following any such acceleration will be subject to the subordination provisions described below under "Subordinated Debt Securities".

At any time after a declaration of acceleration with respect to debt securities of any series has been made, but before a judgment or decree for payment of the money due has been obtained by the trustee, the holders of a majority in principal amount of the outstanding debt securities of that series may rescind and annul the acceleration if all events of default, other than the non-payment of accelerated principal and interest, if any, with respect to debt securities of that series, have been cured or waived as provided in the indenture with respect to the debt securities. No such rescission will affect any subsequent event of default under the indenture with respect to such debt securities or impair any right consequent thereon. We refer you to the prospectus supplement relating to any series of debt securities that are discount securities for the particular provisions relating to acceleration of a portion of the principal amount of such discount securities upon the occurrence of an event of default.

18

The indenture with respect to the debt securities provides that the trustee will be under no obligation to exercise any of its rights or powers under the indenture at the request of any holder of outstanding debt securities, unless the trustee receives indemnity satisfactory to it against any loss, liability or expense. Subject to certain rights of the trustee, the holders of a majority in principal amount of the outstanding debt securities of any series will have the right to direct the time, method and place of conducting any proceeding for any remedy available to the trustee or exercising any trust or power conferred on the trustee with respect to the debt securities of that series.

No holder of any debt security of any series will have any right to institute any proceeding, judicial or otherwise, with respect to the indenture with respect to the debt securities or for the appointment of a receiver or trustee, or for any remedy under the indenture, unless:

Notwithstanding the foregoing, the holder of any debt security will have an absolute and unconditional right to receive payment of the principal of and any interest on that debt security on or after the due dates expressed in that debt security and to institute suit for the enforcement of payment.

Each indenture provides that the trustee may withhold notice to the holders of debt securities of any series of any default or event of default (except in payment on any debt securities of that series) with respect to debt securities of that series if it in good faith determines that withholding notice is in the interest of the holders of those debt securities.

Modification and Waiver

We may modify and amend the indenture with respect to the debt securities with the consent of the holders of at least a majority in principal amount of the outstanding debt securities of each series affected by such modifications or amendments for the purpose of adding any provisions to or changing in any manner the rights of the holders of the debt securities of each such series. In addition, except with respect to those provisions addressed below, the holders of at least a majority in principal amount of the outstanding debt securities of any series may on behalf of the holders of all debt securities of that series waive our compliance with provisions of the indenture with respect to such series of debt securities.

Without the consent of the holders of each affected debt security then outstanding, no amendment or waiver under the indenture may:

19

Defeasance of Debt Securities and Certain Covenants in Certain Circumstances

Legal Defeasance

Each indenture with respect to the debt securities provides that, unless otherwise provided by the terms of the applicable series of debt securities, we may be discharged from any and all obligations in respect of the debt securities of any series (except for certain obligations to register the transfer or exchange of debt securities of such series, to replace stolen, lost or mutilated debt securities of such series, and to maintain paying agencies and certain provisions relating to the treatment of funds held by paying agents) upon the deposit with the trustee, in trust, of money or U.S. government obligations that, through the payment of interest and principal in accordance with their terms, will provide money in an amount sufficient in the opinion of a nationally recognized firm of independent public accountants to pay and discharge each installment of principal and interest on and any mandatory sinking fund payments in respect of the debt securities of that series on the stated maturity of those payments in accordance with the terms of the applicable indenture and those debt securities.

This discharge may occur only if, among other conditions, we have delivered to the trustee an opinion of counsel stating that we have received from, or there has been published by, the U.S. Internal Revenue Service a ruling or, since the date of execution of the indenture with respect to the debt securities, there has been a change in the applicable U.S. federal income tax law, in either case to the effect that, and based thereon such opinion shall confirm that, the holders of the debt securities of that series will not recognize income, gain or loss for U.S. federal income tax purposes as a result of the deposit, defeasance and discharge and will be subject to U.S. federal income tax on the same amounts and in the same manner and at the same times as would have been the case if the deposit, defeasance and discharge had not occurred.

Defeasance of Certain Covenants

Each indenture with respect to the debt securities provides that, unless otherwise provided by the terms of the applicable series of debt securities, upon compliance with certain conditions:

The conditions include:

20

Covenant Defeasance and Events of Default

In the event we exercise our option to effect covenant defeasance with respect to any series of debt securities and the debt securities of that series are declared due and payable because of the occurrence of any event of default, the amount of money or U.S. government obligations on deposit with the trustee will be sufficient to pay amounts due on the debt securities of that series at the time of their stated maturity but may not be sufficient to pay amounts due on the debt securities of that series at the time of the acceleration resulting from the event of default. We will remain liable for those payments.

The Trustee

The indentures limit the right of the trustee, should it become a creditor of us, to obtain payment of claims or secure its claims.

The trustee is permitted to engage in certain other transactions. However, if the trustee acquires any conflicting interest, and there is a default under the debt securities of any series for which it is trustee, the trustee must eliminate the conflict or resign.

Subordinated Debt Securities

Unless otherwise stated in the applicable prospectus supplement, payment of the principal of, premium, if any, and interest on the subordinated debt securities (including the redemption price payable with respect to such subordinated debt securities called for redemption as provided for in the indenture with respect to such subordinated debt securities) will, to the extent provided in the indenture with respect to the subordinated debt securities, be subordinated in right of payment to the prior payment in full of all of our senior indebtedness. The subordinated debt securities also are effectively subordinated to all debt and other liabilities, including trade payables and lease obligations, if any, of our subsidiaries.

Upon any distribution of our assets upon any dissolution, winding up, liquidation or reorganization, the payment of the principal of and interest on the subordinated debt securities will be subordinated in right of payment to the prior payment in full in cash or other payment satisfactory to the holders of senior indebtedness of all senior indebtedness. In the event of any acceleration of the subordinated debt securities because of an event of default, the holders of any senior indebtedness would be entitled to payment in full in cash or other payment satisfactory to such holders of all senior indebtedness obligations before the holders of the subordinated debt securities are entitled to receive any payment or distribution. The indenture with respect to the subordinated debt securities requires us or the trustee to promptly notify holders of designated senior indebtedness if payment of the subordinated debt securities is accelerated because of an event of default.

21

We may not make any payment on the subordinated debt securities, including upon redemption at the option of the holder of any subordinated debt securities or at our option, if:

We may resume payments and distributions on the subordinated debt securities:

No new period of payment blockage may be commenced pursuant to a payment blockage notice unless 365 days have elapsed since the initial effectiveness of the immediately prior payment blockage notice and all scheduled payments of principal, premium and interest on the debt securities that have come due have been paid in full in cash. No non-payment default that existed or was continuing on the date of delivery of any payment blockage notice shall be the basis for any later payment blockage notice.

If the trustee or any holder of the debt securities receives any payment or distribution of our assets in contravention of the subordination provisions on the subordinated debt securities before all senior indebtedness is paid in full in cash, property or securities, including by way of set-off, or other payment satisfactory to holders of senior indebtedness, then such payment or distribution will be held in trust for the benefit of holders of senior indebtedness or their representatives to the extent necessary to make payment in full in cash or payment satisfactory to the holders of senior indebtedness of all unpaid senior indebtedness.

In the event of our bankruptcy, dissolution or reorganization, holders of senior indebtedness may receive more, ratably, and holders of the subordinated debt securities may receive less, ratably, than our other creditors (including our trade creditors). This subordination will not prevent the occurrence of any event of default under the indenture with respect to the subordinated debt securities.

We are not prohibited from incurring debt, including senior indebtedness, under the indenture with respect to the subordinated debt securities. We may from time to time incur additional debt, including senior indebtedness.

We are obligated to pay reasonable compensation to the trustee and to indemnify the trustee against certain losses, liabilities or expenses incurred by the trustee in connection with its duties relating to the subordinated debt securities. The trustee's claims for these payments will generally be senior to those of holders of debt securities in respect of all funds collected or held by the trustee.

Certain Definitions

"indebtedness" means:

22

"senior indebtedness" means the principal, premium, if any, interest, including any interest accruing after bankruptcy, and rent or termination payment on or other amounts due on our current or future indebtedness, whether created, incurred, assumed, guaranteed or in effect guaranteed by us, including any deferrals, renewals, extensions, refundings, amendments, modifications or supplements to the above. However, senior indebtedness does not include:

Governing Law

The indentures and the debt securities will be governed by, and construed in accordance with, the laws of the State of Ohio.

DESCRIPTION OF WARRANTS

We may issue warrants for the purchase of our common shares, preferred shares or of debt securities. We may issue warrants independently or together with other securities, and the warrants may be attached to or separate from any offered securities. Each series of warrants will be issued under a separate warrant agreement to be entered into between us and the investors or a warrant agent.

General

We expect the following provisions will generally apply to warrants we may offer, unless we specify otherwise in the applicable prospectus supplement. The following summary of material provisions of the warrants and warrant agreements are subject to, and qualified in their entirety by reference to, all the provisions of the warrant agreement and warrant certificate applicable to a particular series of warrants. The terms of any warrants offered under a prospectus supplement may differ from the terms described below. We urge you to read the applicable prospectus supplement and any related free writing prospectus, as well as the complete warrant agreements and warrant certificates that contain the terms of the warrants.

23

Terms

The particular terms of any issue of warrants will be described in the prospectus supplement relating to the issue. Those terms may include:

Holders of equity warrants will not be entitled:

Each warrant will entitle its holder to purchase the principal amount of debt securities or the number of common shares or preferred shares at the exercise price set forth in, or calculable as set forth in, the applicable prospectus supplement. Unless we otherwise specify in the applicable prospectus supplement, holders of the warrants may exercise the warrants at any time up to the specified time on the expiration date that we set forth in the applicable prospectus supplement. After the close of business on the expiration date, unexercised warrants will become void.

24

A holder of warrant certificates may exchange them for new warrant certificates of different denominations, present them for registration of transfer and exercise them at the corporate trust office of the warrant agent or any other office indicated in the applicable prospectus supplement. Until any warrants to purchase debt securities are exercised, the holder of the warrants will not have any rights of holders of the debt securities that can be purchased upon exercise, including any rights to receive payments of principal, premium or interest on the underlying debt securities or to enforce covenants in the applicable indenture. Until any warrants to purchase common shares or preferred shares are exercised, the holders of the warrants will not have any rights of holders of the underlying common shares or preferred shares, including any rights to receive dividends or payments upon any liquidation, dissolution or winding up on the common shares or preferred shares, if any.

DESCRIPTION OF SUBSCRIPTION RIGHTS

We may issue subscription rights to purchase debt securities, preferred shares, common shares or other securities. These subscription rights may be issued independently or together with any other security offered hereby and may or may not be transferable by the shareholder receiving the subscription rights in such offering. In connection with any offering of subscription rights, we may enter into a standby arrangement with one or more underwriters or other purchasers pursuant to which the underwriters or other purchasers may be required to purchase any securities remaining unsubscribed after such offering.

In general, a subscription right entitles the holder to purchase for cash a specific number of securities at a specified exercise price. The rights are normally issued to shareholders as of a specific record date, may be exercised only for a limited period of time and become void following the expiration of such period. If we determine to issue subscription rights, we will accompany this prospectus with a prospectus supplement that will describe, among other things:

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 shareholders, 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 PURCHASE CONTRACTS

We may issue purchase contracts, including contracts obligating holders to purchase from us, and us to sell to the holders, our common shares, preferred shares, debt securities, depositary shares or any combination of the foregoing at a future date or dates. The purchase contracts may require us to make periodic payments to the holders of purchase contracts. These payments may be unsecured or prefunded on a basis to be specified in the prospectus supplement relating to the purchase contracts. The purchase contracts may be issued separately or as part of purchase units consisting of a purchase contract and an underlying security.

The prospectus supplement relating to any purchase contracts or purchase units we are offering will specify the material terms of the purchase contracts, the purchase units and any applicable pledge or depository arrangements, including one or more of the following:

25

The descriptions of the purchase contracts, purchase units and any applicable underlying security or pledge or depository arrangements in this prospectus are summaries of the material provisions that would appear in the applicable documents. These descriptions do not include all terms of those documents and do not contain all of the information that you may find useful. The applicable prospectus supplement will describe the terms of any purchase contracts or purchase units in more detail; and we urge you to read the applicable documents because they, and not our summaries and descriptions, will define your rights as holders of the purchase contracts or purchase units. The applicable prospectus supplement will also state whether any of the generalized provisions summarized above do not apply to the purchase contracts, purchase units and any applicable underlying security being offered. The forms of the relevant documents will be filed with the SEC and will be available as described under the heading "WHERE YOU CAN FIND MORE INFORMATION" below.

DESCRIPTION OF UNITS

We may issue units consisting of any combination of the other types of securities offered under this prospectus in one or more series. We may evidence each series of units by unit certificates that we will issue under a separate agreement. We may enter into unit agreements with a unit agent. Each unit agent will be a bank or trust company that we select. We will indicate the name and address of the unit agent in the applicable prospectus supplement relating to a particular series of units.

If we offer any units, certain terms of that series of units will be described in the applicable prospectus supplement, including, without limitation, the following, as applicable:

26

The foregoing description, together with the additional information included in any applicable prospectus supplement, summarizes the general features of the units that we may offer under this prospectus. You should read any prospectus supplement and any free writing prospectus that we may authorize to be provided to you related to the series of units being offered, as well as the complete unit agreements that contain the terms of the units. Specific unit agreements will contain additional important terms and provisions and we will file as an exhibit to the registration statement of which this prospectus is a part, or will incorporate by reference from another report that we file with the SEC, the form of each unit agreement relating to units offered under this prospectus.

PLAN OF DISTRIBUTION

We may sell the securities offered under this prospectus from time to time:

The securities we distribute by any of these methods may be sold, in one or more transactions:

Each time we offer securities under this prospectus, the applicable prospectus supplement will describe the specific plan of distribution and the terms of the offering of the securities, including:

27

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. If we sell securities to underwriters, we will execute an underwriting agreement with the underwriters at the time of sale, and we will name the underwriters in the applicable prospectus supplement. The obligations of the underwriters to purchase the securities will be subject to the conditions set forth in the applicable underwriting agreement. The underwriters may resell the securities from time to time in one or more transactions, including negotiated transactions. The underwriters may sell the securities in order to facilitate transactions in any of our other securities (described in this prospectus or otherwise), including other public or private transactions and short sales. The underwriters may offer securities to the public either through underwriting syndicates represented by one or more managing underwriters or directly by one or more firms acting as underwriters. The underwriters may change from time to time any initial public offering price and any discounts or concessions allowed or reallowed or paid to dealers.

In connection with sales to underwriters, the underwriters may be deemed to have received compensation from us in the form of underwriting discounts or commissions and may also receive commissions from purchasers of the securities for whom they may act as agents. Underwriters may resell the securities to or through dealers, and those dealers may receive compensation in the form of discounts, concessions or commissions from the underwriters and/or commissions from purchasers for whom they may act as agents. The applicable prospectus supplement will include any required information about underwriting compensation we pay to underwriters, and any discounts, concessions or commissions underwriters allow to participating dealers, in connection with an offering of securities.

From time to time, we may sell securities to one or more dealers acting as principals. The dealers, who may be deemed to be underwriters within the meaning of the Securities Act, may then resell those securities to the public. The applicable prospectus supplement will include the names of the dealers and the terms of the transaction.

We may solicit offers to purchase securities directly from the public from time to time. In this case, no underwriters or agents would be involved. We may also designate agents from time to time to solicit offers to purchase securities from the public on our behalf. Such agents may be deemed to be underwriters within the meaning of the Securities Act. The applicable prospectus supplement relating to any particular offering of securities will name any agents designated to solicit offers and will include information about any compensation we may pay the agents in connection with that offering. Unless otherwise indicated in the applicable prospectus supplement, any agent will agree to use its reasonable best efforts to solicit purchases for the period of its appointment.

We may sell the securities directly to institutional investors or others. These persons may be deemed to be underwriters within the meaning of the Securities Act with respect to any sale of those securities. The terms of any such direct sales will be described in the applicable prospectus supplement.

We may make direct sales of the securities through subscription rights distributed to our existing securityholders on a pro rata basis, which may or may not be transferable. In any distribution of subscription rights, if all of the underlying securities are not subscribed for, we may then sell the unsubscribed securities directly to third parties or we may engage the services of one or more underwriters, dealers or agents, including standby underwriters, to sell the unsubscribed securities to third parties. The terms of any such sales or arrangements will be described in the applicable prospectus supplement.

We may authorize underwriters, dealers and agents to solicit from certain types of institutional investors offers to purchase securities under delayed delivery contracts providing for payment and delivery on future dates. The applicable prospectus supplement will describe the material terms of these contracts, including any conditions to the purchasers' obligations, and will include any required information about commissions we may pay for soliciting these contracts.

We may authorize one or more "remarketing firms" to sell securities pursuant to a remarketing arrangement upon the purchase of the securities. Remarketing firms will act as principals for their own accounts or as agents for us, and will offer or sell the securities in accordance with a redemption or repayment pursuant to the terms of the securities, or otherwise. The applicable prospectus supplement will identify any remarketing firm and describe the terms of its compensation and agreements, if any, with us. Remarketing firms may be deemed to be underwriters within the meaning of the Securities Act with respect to the securities they remarket.

Unless the applicable prospectus supplement states otherwise, the securities offered under this prospectus (other than our common shares) will be a new issue of securities with no established trading market. We may elect to list any series of offered securities on an exchange. Any underwriters that we use in the sale of offered securities may make a market in such securities, but may discontinue such market making at any time without notice. Therefore, we cannot assure you that the securities will have a liquid trading market.

28

Any underwriters that we use in the sale of offered securities may engage in over-allotment, stabilizing transactions, syndicate covering transactions and penalty bids in accordance with Regulation M under the Exchange Act. Over-allotment involves sales in excess of the offering size, which create a short position. Stabilizing transactions involve bids to purchase the underlying securities in the open market for the purpose of pegging, fixing or maintaining the price of the securities. Syndicate covering transactions involve purchases of the securities, either through exercise of the over-allotment option or in the open market after the distribution has been completed, in order to cover short positions. Penalty bids permit the underwriters to reclaim a selling concession from a syndicate member when the securities originally sold by the syndicate member are purchased in a syndicate covering transaction to cover short positions. These activities may cause the price of the securities to be higher than it would be in the absence of the transactions. The underwriters may, if they commence these transactions, discontinue them at any time.

Any underwriters, dealers or agents participating in the distribution of the offered securities may be deemed to be underwriters under the Securities Act, and any compensation and profits received by such persons upon sale of the securities may be deemed to be underwriting discounts and commissions under the Securities Act. Underwriters, dealers, agents and other persons may be entitled, under agreements that they may enter into with us, to indemnification by us against certain liabilities, including liabilities under the Securities Act, or to contribution with respect to payments that such persons make with respect to these liabilities. Our underwriters, dealers and agents, or their affiliates, may be customers of, engage in transactions with, or perform services for, us in the ordinary course of business.

LEGAL MATTERS

Vorys, Sater, Seymour and Pease LLP will pass upon certain legal matters relating to the issuance and sale of the securities offered hereby on behalf of Civista. Additional legal matters may be passed upon for us or any underwriters, dealers or agents, by counsel that we will name in the applicable prospectus supplement.

EXPERTS

The consolidated financial statements of Civista appearing in its Annual Report on Form 10-K for the year ended December 31, 2020, and the effectiveness of Civista Bancshares, Inc. and its subsidiaries' internal control over financial reporting as of December 31, 2020, have been audited by S.R. Snodgrass, P.C., an independent registered public accounting firm, as set forth in their reports thereon, included therein, and incorporated herein by reference. Such consolidated financial statements are incorporated herein by reference in reliance upon such reports given on the authority of such firm as experts in accounting and auditing.

WHERE YOU CAN FIND MORE INFORMATION

We file annual, quarterly and current reports, proxy statements and other information with the SEC. The SEC maintains an Internet website that contains reports, proxy and information statements and other information regarding issuers, including us, that file electronically with the SEC. The address for the SEC's website is www.sec.gov.

We make available, free of charge, on our website at www.civb.com, our annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K and amendments to those reports and statements as soon as reasonably practicable after they are filed with the SEC. The contents of our website are not part of this prospectus, and the reference to our website does not constitute incorporation by reference into this prospectus of the information contained at that site, other than documents we file with the SEC that are incorporated by reference into this prospectus.

This prospectus and any prospectus supplement are part of a registration statement that we filed with the SEC and do not contain all of the information in the registration statement. The full registration statement may be obtained from the SEC or us, as provided above. Forms of the indenture and other documents establishing the terms of the offered securities are or may be filed as exhibits to the registration statement. Statements in this prospectus or any prospectus supplement about these documents are summaries and each statement is qualified in all respects by reference to the document to which it refers. You should refer to the actual documents for a more complete description of the relevant matters.

29

INCORPORATION BY REFERENCE

The SEC allows us to "incorporate by reference" information into this prospectus, which means that we can disclose important information to you by referring you to another document filed separately with the SEC. The information incorporated by reference is deemed to be part of this prospectus, and subsequent information that we file with the SEC will automatically update and supersede that information. Any statement contained in a previously filed document incorporated by reference will be deemed to be modified or superseded for purposes of this prospectus to the extent that a statement contained in this prospectus modifies or replaces that statement.

We incorporate by reference our documents listed below and any future filings made by us with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act between the date of this prospectus and the termination of the offering of the securities described in this prospectus. We are not, however, incorporating by reference any documents or portions thereof, whether specifically listed below or filed in the future, that are furnished and not deemed "filed" with the SEC, including any information furnished pursuant to Item 2.02 or Item 7.01 of our current reports on Form 8-K after the date of this prospectus unless, and except to the extent, specified in such current reports.

This prospectus and any accompanying prospectus supplement incorporate by reference the documents set forth below that have previously been filed with the SEC under SEC File No. 36192:

All reports and other documents we subsequently file pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act prior to the termination of this offering, including all such documents we may file with the SEC after the date of the initial registration statement and prior to the effectiveness of the registration statement, but excluding any information furnished to, rather than filed with, the SEC, will also be incorporated by reference into this prospectus and deemed to be part of this prospectus from the date of the filing of such reports and documents.

We will provide to each person to whom this prospectus is delivered, upon written or oral request, without charge, a copy of any or all of the documents that are incorporated by reference into this prospectus (other than exhibits, unless they are specifically incorporated by reference in the documents) and a copy of any or all other contracts, agreements or documents which are referred to in this prospectus or any accompanying prospectus supplement. Requests should be directed to:

Civista Bancshares, Inc.

Attention: Dennis G. Shaffer

100 East Water Street

Sandusky, Ohio 44870

Telephone number: (419) 625-4121

30

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14. Other Expenses of Issuance and Distribution.

The following is an estimate of the expenses (all of which are to be paid by the registrant) that we may incur in connection with the securities being registered hereby, other than the SEC registration fee.

Item 15. Indemnification of Directors and Officers.

Ohio General Corporation Law

Ohio General Corporation Law Section 1701.13(E) grants corporations broad powers to indemnify directors, officers, employees and agents. Section 1701.13(E)(1) of the Ohio General Corporation Law provides that a corporation may indemnify or agree to 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 the corporation, by reason of the fact that he is or was a director, officer, employee, or agent of the corporation, or is or was serving at the request of the corporation as a director, trustee, officer, employee, member, manager, or agent of another corporation, domestic or foreign, nonprofit or for profit, a limited liability company, or a partnership, joint venture, trust, or other enterprise, against expenses, including attorneys' fees, judgments, fines, and amounts paid in settlement actually and reasonably incurred by him in connection with such action, suit, or proceeding, if he acted in good faith and in a manner he reasonably believed to be in or not opposed to the best interests of the corporation, and, with respect to any criminal action or proceeding, if he had no reasonable cause to believe his conduct was unlawful. The termination of any action, suit, or proceeding by judgment, order, settlement, or conviction, or upon a plea of nolo contendere or its equivalent, shall not, of itself, create a presumption that the person did not act in good faith and in a manner he reasonably believed to be in or not opposed to the best interests of the corporation, and, with respect to any criminal action or proceeding, that he had reasonable cause to believe that his conduct was unlawful.

Section 1701.13(E)(2) further specifies that a corporation may indemnify or agree to indemnify any person who was or is a party, or is threatened to be made a party, to any threatened, pending, or completed action or suit by or in the right of the corporation to procure a judgment in its favor, by reason of the fact that he is or was a director, officer, employee, or agent of the corporation, or is or was serving at the request of the corporation as a director, trustee, officer, employee, member, manager, or agent of another corporation, domestic or foreign, nonprofit or for profit, a limited liability company, or a partnership, joint venture, trust, or other enterprise, against expenses, including attorneys' fees, actually and reasonably incurred by him in connection with the defense or settlement of such action or suit, if he acted in good faith and in a manner he reasonably believed to be in or not opposed to the best interests of the corporation, except that no indemnification shall be made in respect of (a) any claim, issue, or matter as to which such person shall have been adjudged to be liable for negligence or misconduct in the performance of his duty to the corporation unless, and only to the extent, that the court of common pleas or the court in which such action or suit was brought determines, upon application, that, despite the adjudication of liability, but in view of all the circumstances of the case, such person is fairly and reasonably entitled to indemnity for such expenses as the court of common pleas or such other court shall deem proper, and (b) any action or suit in which the only liability asserted against a director is pursuant to Section 1701.95 of the Ohio General Corporation Law concerning unlawful loans, dividends and distribution of assets.

II-1

In addition, Section 1701.13(E)(5)(a) requires a corporation to pay any expenses, including attorneys' fees, of a director in defending an action, suit, or proceeding referred to above as they are incurred, in advance of the final disposition of the action, suit, or proceeding, upon receipt of an undertaking by or on behalf of the director in which he agrees to both (i) repay such amount if it is proved by clear and convincing evidence that his action or failure to act involved an act or omission undertaken with deliberate intent to cause injury to the corporation or undertaken with reckless disregard for the best interests of the corporation and (ii) reasonably cooperate with the corporation concerning the action, suit, or proceeding. Section 1701.13(E)(7) and (F)(2) further authorizes a corporation to enter into contracts regarding indemnification and to purchase and maintain insurance on behalf of any director, trustee, officer, employee or agent for any liability asserted against him or arising out of his status as such.

Articles of Incorporation and Code of Regulations

Pursuant to Article EIGHTH of the Articles of Incorporation, Civista has the power to indemnify its present and past directors, officers, employees and agents to the fullest extent permitted under the Ohio Revised Code. ARTICLE VIII of the Code of Regulations provides that Civista will indemnify, to the fullest extent permitted or authorized by applicable law, any person made or threatened to be made a party to any suit or proceeding, whether civil, criminal, administrative or investigative, by reason of the fact that he or she is or was a director, officer or employee of Civista, or is or was serving at the request of Civista as a director, trustee, officer, or employee of a bank, or other corporation, partnership, joint venture, trust or other enterprise. In order to receive indemnification, the person must have acted in good faith and in a manner that he or she reasonably believed to be in and not opposed to the best interest of Civista. With regard to any criminal action or proceeding, Civista will indemnify the person if he or she had no reasonable cause to believe his or her conduct was unlawful. Civista will not indemnify a person with respect to such person's willful misconduct.

As a condition precedent to Civista providing such indemnification, the person to be indemnified must (i) promptly notify Civista of any actual or potential action, suit or proceeding, (ii) except with respect to a criminal proceeding, authorize and permit Civista, in its sole discretion, to choose any legal counsel to defend and otherwise handle the action, suit or proceeding and related matters, (iii) except with respect to a criminal proceeding, permit Civista to assume total, complete and exclusive control of the action, suit or proceedings and all related proceedings and matters, and (iv) in all respects, cooperate with Civista and its counsel in the defense and/or settlement of the action, suit or proceeding and in the prosecution and/or settlement of any counterclaims, cross-claims and defenses.

The indemnification provided by Civista's Code of Regulations is not exclusive of any other rights to which any person seeking indemnification may be entitled, both as to action in his or her official capacity and as to action in another capacity while holding such office. In addition, such indemnification will continue as to a person who has ceased to be a director, trustee, officer or employee and will inure to the benefit of such person's heirs, executors and administrators.

Insurance

Article EIGHTH of the Articles of Incorporation provide that, upon the vote of a majority of its Board of Directors, Civista may purchase insurance for the purpose of indemnifying its directors, officers, employees and agents to the extent that such indemnification is allowed under the Articles of Incorporation. Civista has purchased and maintains insurance policies that insure its directors and officers against certain liabilities that might be incurred by them in their capacities as directors and officers.

Item 16. Exhibits

II-2

Item 17. Undertakings

The undersigned registrant hereby undertakes:

(a) (1) To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement:

(i) To include any prospectus required by Section 10(a)(3) of the Securities Act of 1933, as amended (the "Securities Act");

II-3

(ii) To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the SEC pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than 20 percent change in the maximum aggregate offering price set forth in the "Calculation of Registration Fee" table in the effective registration statement; and

(iii) To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement;

provided, however, that paragraphs (a)(1)(i), (a)(1)(ii), and (a)(1)(iii) above 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 Securities Exchange Act of 1934 that are incorporated by reference in the registration statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is a part of the registration statement.

(2) That, for the purpose of determining any liability under the Securities Act, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

(4) That, for the purpose of determining liability under the Securities Act to any purchaser:

(i) Each prospectus filed by the registrant pursuant to Rule 424(b)(3) shall be deemed to be part of the registration statement as of the date the filed prospectus was deemed part of and included in the registration statement; and

(ii) Each prospectus required to be filed pursuant to Rule 424(b)(2), (b)(5), or (b)(7) as part of a registration statement in reliance on Rule 430B relating to an offering made pursuant to Rule 415(a)(1)(i), (vii), or (x) for the purpose of providing the information required by Section 10(a) of the Securities Act shall be deemed to be part of and included in the registration statement as of the earlier of the date such form of prospectus is first used after effectiveness or the date of the first contract of sale of securities in the offering described in the prospectus. As provided in Rule 430B, for liability purposes of the issuer and any person that is at that date an underwriter, such date shall be deemed to be a new effective date of the registration statement relating to the securities in the registration statement to which that prospectus relates, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. Provided, however, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such effective date, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such effective date.

(5) That, for the purpose of determining liability of the registrant under the Securities Act to any purchaser in the initial distribution of securities, the undersigned registrant undertakes that in a primary offering of securities of the undersigned registrant pursuant to this registration statement, regardless of the underwriting method used to sell the securities to the purchaser, if the securities are offered or sold to such purchaser by means of any of the following communications, the undersigned registrant will be a seller to the purchaser and will be considered to offer or sell such securities to such purchaser:

II-4

(i) Any preliminary prospectus or prospectus of the undersigned registrant relating to the offering required to be filed pursuant to Rule 424;

(ii) Any free writing prospectus relating to the offering prepared by or on behalf of the undersigned registrant or used or referred to by the undersigned registrant;

(iii) The portion of any other free writing prospectus relating to the offering containing material information about the undersigned registrant or its securities provided by or on behalf of the undersigned registrant; and

(iv) Any other communications that is an offer in the offering made by the undersigned registrant to the purchaser.

(b) The undersigned registrant hereby undertakes that, for purposes of determining any liability under the Securities Act, each filing of the registrant's annual report pursuant to Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing of an employee benefit plan's annual report pursuant to Section 15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(c) The undersigned registrant hereby undertakes to supplement the prospectus, after the expiration of the subscription period, to set forth the results of the subscription offer, the transactions by the underwriters during the subscription period, the amount of unsubscribed securities to be purchased by the underwriters, and the terms of any subsequent reoffering thereof. If any public offering by the underwriters is to be made on terms differing from those set forth on the cover page of the prospectus, a post-effective amendment will be filed to set forth the terms of such offering.

(d) 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 foregoing provisions, 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.

(e) The undersigned registrant hereby undertakes to file an application for the purpose of determining the eligibility of the trustee to act under subsection (a) of Section 310 of the Trust Indenture Act in accordance with the rules and regulations prescribed by the SEC under section 305(b)(2) of the Act.

II-5

SIGNATURES

Pursuant to the requirements of the Securities Act, 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 Amendment No.1 to Registration Statement on Form S-3 to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Sandusky, State of Ohio, on the 22nd day of October, 2021.

Pursuant to the requirements of the Securities Act, this Form S-3 has been signed by the following persons in the capacities and on the dates indicated.

II-6