FGBI First Guaranty Bancshares Inc

Filed pursuant to Rule 424(b)(5)
Registration Statement No. 333-221335

Prospectus Supplement
To the Prospectus Dated November 14, 2017

FIRST GUARANTY BANCSHARES, INC.

Up to $25,000,000

Common Stock

We have entered into a distribution agreement, dated November 20, 2017, with Sandler O’Neill & Partners, L.P. (“Sandler O’Neill”), as our sales agent, for the offer and sale from time to time of shares of our common stock, par value $1.00 per share, having an aggregate gross sales price of up to $25,000,000 offered by this prospectus supplement and the accompanying prospectus.

Sales of our common stock, if any, under this prospectus supplement and the accompanying prospectus will be made in sales deemed to be “at-the-market offerings” as defined in Rule 415 under the Securities Act of 1933, as amended, or the Securities Act. The shares of common stock generally will be offered and sold through Sandler O’Neill over a period of time and from time to time made by means of ordinary broker transactions on the NASDAQ Global Market at market prices prevailing at the time, at prices related to such market prices, at negotiated prices, or any other method permitted by law, pursuant to the distribution agreement.

Accordingly, an indeterminate number of shares of common stock will be sold up to that number of shares having an aggregate gross sales price of up to $25,000,000. We will pay Sandler O’Neill a commission of up to 3.0% of the gross sales price per share agreed upon at the time of sale. The net proceeds we receive from the sale of the shares will be the gross proceeds received from such sales less the commissions and other costs we may incur in issuing the shares. See “Plan of Distribution” in this prospectus supplement for further information.

Our sales agent is not required to sell any specific number or dollar amount of shares of our common stock. Subject to the terms and conditions of the distribution agreement, Sandler O’Neill will use its commercially reasonable efforts, as our agent, to sell on our behalf any common stock to be offered, as instructed by us. The offering of our common stock pursuant to the distribution agreement will terminate upon the earlier of (1) the sale of all of the shares of our common stock subject to the distribution agreement and (2) the termination of the distribution agreement by us, by our sales agent, or by its terms, as applicable.

We also may sell shares or we may sell shares to Sandler O’Neill as principal for its own account, at a price agreed upon at the time of sale. If we sell shares to Sandler O’Neill as principal or other than in accordance with the distribution agreement, we will enter into a separate agreement setting forth the terms of such transaction and we will describe such agreement in a separate prospectus supplement or pricing supplement.

Our common stock is listed on the NASDAQ Global Market under the symbol “FGBI.” On November 17, 2017, the last reported price of our common stock on the NASDAQ Global Market was $25.97 per share.

Investing in our common stock involves risks. Please carefully review the risks discussed in “Risk Factors” beginning on page S- 3 of this prospectus supplement and in risk factors included in certain of the documents incorporated by reference in this prospectus supplement for a description of factors you should consider before making your investment decision.

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

The shares of our common stock are not savings accounts, deposits or obligations of a bank or savings association and are not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

S ANDLER O’N EILL + P ARTNERS , L.P.

The date of this prospectus supplement is November 20, 2017.

These statements are not guarantees of future performance and are subject to risks, uncertainties and other factors, many of which are beyond the Company’s control, that could cause actual conditions or results to differ materially from those expressed or implied by such forward-looking statements. These factors include, without limitation, the following:

In addition, we routinely evaluate opportunities to expand through acquisitions and periodically conduct due diligence activities in connection with such opportunities. As a result, acquisition discussions and, in some cases, negotiations, may take place at any time, and acquisitions involving cash or our debt or equity securities may occur.

We assume no obligation for updating our forward-looking statements at any time. When considering these forward-looking statements, you should keep in mind these risks and uncertainties, as well as the other cautionary statements made in this prospectus supplement and the accompanying prospectus and our other periodic and current reports filed with the SEC. You should not place undue reliance on any forward-looking statement, which speaks only as of the date made. You should refer to our periodic and current reports filed with the SEC for specific risks that could cause actual results to be significantly different from those expressed or implied by these forward-looking statements. See “Where You Can Find More Information” and “Risk Factors” below.

PROSPECTUS SUPPLEMENT SUMMARY

This summary highlights selected information about us, this offering and information appearing elsewhere in this prospectus supplement and in the accompanying prospectus and in the documents we incorporate by reference. This summary is not complete and does not contain all of the information you should consider before investing in the securities offered by this prospectus supplement. You should read this summary together with the entire prospectus supplement, including the section entitled “Risk Factors” beginning on page S- 3 , the accompanying prospectus, and the other documents that are incorporated by reference in this prospectus, including our financial statements and the notes to those financial statements, before making an investment decision.

General

First Guaranty Bancshares, Inc. is the holding company for First Guaranty Bank, a Louisiana state-chartered bank. Founded in 1934, First Guaranty Bank provides personalized commercial banking services primarily to Louisiana and Texas customers through 27 banking facilities primarily located throughout Southeast, Southwest and North Louisiana and in North Central Texas.

Our principal business consists of attracting deposits from the general public and local municipalities in our market areas and investing those deposits, together with funds generated from operations and borrowings in lending and in securities activities to serve the credit needs of our customer base, including commercial real estate loans, commercial and industrial loans, one- to four-family residential real estate loans, construction and land development loans, agricultural and farmland loans, and to a lesser extent, consumer and multifamily loans. We also participate in certain syndicated loans, including shared national credits, with other financial institutions. We offer a variety of deposit accounts to consumers and small businesses, including personal and business checking and savings accounts, time deposits, money market accounts and demand accounts. We invest a portion of our assets in securities issued by the United States Government and its agencies, state and municipal obligations, corporate debt securities, mutual funds, and equity securities. We also invest in mortgage-backed securities primarily issued or guaranteed by United States Government agencies or enterprises. In addition, we offer a broad range of consumer services, including personal and commercial credit cards, remote deposit capture, safe deposit boxes, official checks, internet banking, automated teller machines, online bill pay, mobile banking and lockbox services.

We are registered as a bank holding company under the Bank Holding Company Act of 1956, as amended. As a bank holding company, we are subject to regulation and examination by the Board of Governors of the Federal Reserve System (the “Federal Reserve Board”) and the Federal Reserve Bank of Atlanta under delegated authority from the Federal Reserve Board. As a Federal Deposit Insurance Corporation (“FDIC”) insured, Louisiana state chartered bank, First Guaranty Bank is subject to regulation and examination by the FDIC and the Louisiana Office of Financial Institutions (the “OFI”). First Guaranty Bank also is a member of the Federal Home Loan Bank of Dallas (“FHLB”), which provides it with a source of funds in the form of short-term and long-term borrowings.

At September 30, 2017, we had total consolidated assets of $1.7 billion, total deposits of $1.5 billion and total shareholders’ equity of $142.8 million.

Our principal executive offices are located at 400 East Thomas Street, Hammond, Louisiana 70401, and our telephone number at this address is (985) 345-7685. Our website address is www.fgb.net. The information contained on our website should not be considered part of this prospectus supplement or the accompanying prospectus, and the reference to our website does not constitute incorporation by reference of the information contained on the website. Additional information about us is included in documents incorporated by reference in this prospectus supplement. See “ Where You Can Find More Information ” on page S- 8 of this prospectus supplement.

Recent Developments

On June 16, 2017, First Guaranty Bancshares completed its merger with Premier Bancshares, Inc. First Guaranty Bancshares acquired an estimated total of $158.3 million in assets and assumed an estimated $137.4 million in liabilities. This acquisition provided First Guaranty Bancshares the opportunity to expand into the North Central Texas market area with five branch locations.

exchangeable for, or that represent the right to receive, common stock. Because our decision to issue securities in any future offering will depend on market conditions and other factors beyond our control, we cannot predict or estimate the amount, timing or nature of any future offerings, or the prices at which such offerings may be affected. Such offerings could be dilutive to common shareholders. New investors also may have rights, preferences and privileges that are senior to, and that adversely affect, our then current common shareholders. If we raise additional capital by selling preferred equity securities, upon liquidation, holders of our shares of preferred stock, and lenders with respect to other borrowings, will receive distributions of our available assets prior to the holders of our common stock. Additional equity offerings may dilute the holdings of our existing shareholders or reduce the market price of our common stock, or both. Holders of our common stock are not entitled to preemptive rights or other protections against dilution.

We may reduce or eliminate the cash dividend on our common stock.

Holders of our common stock are only entitled to receive such cash dividends as our board of directors may declare out of funds legally available for such payments. Although we have historically declared cash dividends on our common stock, we are not required to do so and may reduce or eliminate our common stock cash dividend in the future. This could adversely affect the market price of our common stock. Moreover, the issuance of any senior preferred shares in the future may affect our ability to pay dividends on our common stock unless all dividends on any such senior preferred shares have been paid in full. Also, as a bank holding company, our ability to declare and pay dividends is dependent on certain federal regulatory considerations including the guidelines of the Federal Reserve Board regarding capital adequacy and dividends. See “Market for Common Stock and Our Dividend Policy” for more information.

An investment in our common stock is not an insured deposit and is not guaranteed by the FDIC, so you could lose some or all of your investment.

Our common stock is not a bank deposit and, therefore, is not insured against loss by the FDIC or any other public or private entity. Investment in our common stock is inherently risky for the reasons described in this “Risk Factors” section, elsewhere in this prospectus supplement and the accompanying prospectus, and the additional documents and information incorporated by reference, and is subject to the same market forces that affect the common stock in any company. As a result, if you acquire our common stock, you may lose some or all of your investment.

The number of shares of our common stock available for future sale could adversely affect the market price of our common stock.

We cannot predict whether future issuances of shares of our common stock or the availability of shares for resale in the open market will decrease the market price per share of our common stock. We may sell shares of our common stock under this prospectus supplement with an aggregate gross offering price of up to $25,000,000. We may also sell additional shares of our common stock in the future under the prospectus which accompanies this prospectus supplement or in other offerings or other acquisitions we may undertake. Sales of substantial amounts of shares of our common stock in the public market, or the perception that such sales might occur, could adversely affect the market price of our common stock.

We have broad discretion in the use of net proceeds from this offering, and our use of those proceeds may not yield a favorable return on your investment.

We expect to use the net proceeds, if any, of this offering for general corporate purposes, including support for organic growth and financing possible acquisitions of other financial institutions. Our management has broad discretion over how these proceeds are used and could spend the proceeds in ways with which you may not agree. In addition, we may not use the proceeds of this offering effectively or in a manner that increases our market value or enhances our profitability. We have not established a timetable for the effective deployment of the proceeds, and we cannot predict how long it will take to deploy the proceeds. Investing the offering proceeds in securities until we are able to deploy the proceeds will provide lower yields than we generally earn on loans, potentially adversely affecting our net interest yield and our net interest margin.

Substantial regulatory limitations on changes of control and anti-takeover provisions in our articles of incorporation and bylaws may make it more difficult for you to receive a change in control premium.

With certain limited exceptions, federal regulations prohibit a person or company or a group of persons deemed to be “acting in concert” from, directly or indirectly, acquiring more than 10% (5% if the acquirer is a

bank holding company) of any class of our voting stock or obtaining the ability to control in any manner the election of a majority of our directors or otherwise direct the management or policies of our company without prior notice or application to and the approval of the Federal Reserve Board.

In addition, our restated articles of incorporation and bylaws contain a number of provisions relating to corporate governance and rights of shareholders that might discourage future takeover attempts. See “Description of the Securities—Description of Common Stock— Restrictions on Acquisition of First Guaranty Bancshares” on page 14 of the accompanying prospectus.

Share ownership by our directors and officers may make it more difficult for third parties to acquire us or effectuate a change of control that might be viewed favorably by other shareholders.

As of November 17, 2017, our directors and executive officers owned, in the aggregate, approximately 40.2% of our outstanding shares. As a result, if our directors and executive officers were to oppose a third party’s acquisition proposal for, or a change in control of, the Company, our directors and executive officers may have sufficient voting power to be able to block or at least delay such an acquisition or change in control from taking place, even if other shareholders would support such a sale or change of control.

Risks Relating to Our Business

For risks associated with our business and industry, see the section entitled “Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2016, which is incorporated in this prospectus supplement and the accompanying prospectus by reference, as the same may be updated from time to time by our future filings under the Exchange Act.

Subject to satisfying such requirement, First Guaranty Bank may pay dividends to the Company without the approval of the OFI so long as the amount of the dividend does not exceed its net profits earned during the current year combined with its retained earnings for the immediately preceding year. The OFI must approve any proposed dividend in excess of this threshold. In addition, as a depository institution the deposits of which are insured by the FDIC, the Bank may not pay dividends or distribute any of its capital assets while it remains in default on any assessment due to the FDIC. The Bank currently is not, and never has been, in default under any of its obligations to the FDIC.

The Federal Reserve Board has issued a policy statement regarding the payment of dividends by bank holding companies. In general, the Federal Reserve Board’s policy provides that dividends should be paid only out of current earnings and only if the prospective rate of earnings retention by the bank holding company appears consistent with the organization’s capital needs, asset quality and overall financial condition. The Federal Reserve Board has the authority to prohibit us from paying dividends if such payment is deemed to be an unsafe or unsound practice.

Under the terms of the distribution agreement, we also may sell shares of our common stock to Sandler O’Neill, as principal for its own account, at a price agreed upon at the time of sale. If we sell shares to Sandler O’Neill as principal or other than in accordance with the distribution agreement, we will enter into a separate agreement with Sandler O’Neill, and we will describe such agreement in a separate prospectus supplement or pricing supplement. We will report in a prospectus supplement and/or filings under the Exchange Act at least quarterly the number of shares of our common stock sold through Sandler O’Neill under the distribution agreement, the net proceeds to us and the compensation paid by us to Sandler O’Neill in connection with the sales of our common stock.

In connection with the sale of common stock on our behalf, Sandler O’Neill may be deemed to be an “underwriter” within the meaning of the Securities Act, and the compensation paid to Sandler O’Neill may be deemed to be underwriting commissions or discounts. We have agreed in the distribution agreement to indemnify Sandler O’Neill against certain specified liabilities, including liabilities under the Securities Act, or to contribute to payments that Sandler O’Neill may be required to make because of those liabilities.

In the ordinary course of its business, Sandler O’Neill and/or its affiliates have engaged and may engage in commercial and investment banking transactions, financial advisory and other transactions with us. They have received, or may receive, customary compensation and expenses. To the extent required by Regulation M, Sandler O’Neill will not engage in any market making activities involving our common stock while the offering is ongoing under this prospectus supplement.

The offering of shares of our common stock pursuant to the distribution agreement will terminate upon the earlier of (1) the sale of all shares of common stock subject to the distribution agreement, up to an aggregate gross sales price of $25,000,000 and (2) the termination of the distribution agreement by us or by Sandler O’Neill.

PROSPECTUS

FIRST GUARANTY BANCSHARES, INC.

$50,000,000

Debt Securities
Common Stock
Preferred Stock
Depositary Shares
Warrants
Purchase Contracts
Units
Subscription Rights

We may offer and sell, from time to time up to $50.0 million, in one or more series, our unsecured debt securities, which may consist of notes, debentures, or other evidences of indebtedness; shares of our common stock; shares of our preferred stock; depositary shares; purchase contracts; warrants to purchase other securities; units; or subscription rights consisting of any combination of the above securities. The debt securities and preferred stock may be convertible into or exchangeable for other securities of ours. This prospectus provides you with a general description of these securities. Each time we offer any securities pursuant to this prospectus, we will provide you with a prospectus supplement, and, if necessary, a pricing supplement, that will describe the specific amounts, prices and terms of the securities being offered. These supplements may also add, update or change information contained in this prospectus. To understand the terms of the securities offered, you should carefully read this prospectus with the applicable supplements, which together provide the specific terms of the securities we are offering.

Our common stock is traded on the Nasdaq Global Market under the symbol “FGBI.”

This prospectus may be used to offer and sell securities only if accompanied by the prospectus supplement and any applicable pricing supplement for those securities.

We are an “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012 and, as a result, are subject to reduced public company disclosure standards. See “Implications of Being an Emerging Growth Company.”

You should read this prospectus and any supplements carefully before you invest. Investing in our securities involves a high degree of risk. See the sections entitled “Risk Factors,” on page 4 of this prospectus, in any prospectus supplement and in the documents we file with the Securities and Exchange Commission that are incorporated in this prospectus by reference for a discussion of certain risks and uncertainties you should consider.

These securities are not deposits or obligations of a bank or savings association and are not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

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

The date of this prospectus is November 14, 2017.

IMPORTANT NOTICE ABOUT INFORMATION PRESENTED IN THIS
PROSPECTUS AND THE ACCOMPANYING PROSPECTUS SUPPLEMENT

We may provide information to you about the securities we offer in three separate documents that progressively provide more detail:

If the terms of your securities vary among the pricing supplement, the prospectus supplement and the prospectus, you should rely on the information in the following order of priority:

We include cross-references in this prospectus and the prospectus supplement to captions in these materials where you can find further related discussions. The following Table of Contents and the Table of Contents included in a prospectus supplement provide the pages on which these captions are located.

Unless indicated in the applicable prospectus supplement, we have not taken any action that would permit us to publicly sell these securities in any jurisdiction outside the United States. If you are an investor outside the United States, you should inform yourself about, and comply with, any restrictions as to the offering of the securities and the distribution of this prospectus.

IMPLICATIONS OF BEING AN EMERGING GROWTH COMPANY

As a company with less than $1.07 billion in annual gross revenues during our last fiscal year, we qualify as an “emerging growth company” under the Jumpstart Our Business Startups Act of 2012, or the JOBS Act. An emerging growth company may take advantage of specified reduced reporting requirements and is relieved of certain other significant requirements that are otherwise generally applicable to other public companies. As an emerging growth company:

We may take advantage of these provisions for up to five years from the completion of our initial public offering in November 2015 unless we earlier cease to be an emerging growth company. We will cease to be an emerging growth company if we have more than $1.07 billion in annual gross revenues, have more than $700.0 million in market value of our common stock held by non-affiliates, or issue more than $1.0 billion of non-convertible debt in a three-year period. We have elected to adopt the reduced disclosure requirements described above regarding our executive compensation arrangements for purposes of the registration statement of which this prospectus is a part. In addition, we expect to take advantage of certain of the reduced reporting and

other requirements of the JOBS Act with respect to the periodic reports we will file with the SEC and proxy statements that we use to solicit proxies from our shareholders.

The JOBS Act also permits us an extended transition period for complying with new or revised financial accounting standards affecting public companies until they would apply to private companies. However, we have elected not to take advantage of this extended transition period, which means that the financial statements included or incorporated by reference in this prospectus, as well as any financial statements that we file in the future, will be subject to all new or revised accounting standards generally applicable to public companies. Our election not to take advantage of the extended transition period is irrevocable.

TABLE OF CONTENTS

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission (the “SEC”) utilizing a “shelf” registration process. Under this shelf registration process, we may offer and sell, from time to time, the debt securities, common stock, preferred stock, depositary shares, warrants, purchase contracts, units or subscription rights consisting of a combination of any of the securities described in this prospectus in one or more offerings, up to a total dollar amount of $50.0 million. This prospectus provides you with a general description of the securities that we may offer. Each time we offer these securities, we will provide a prospectus supplement and, if necessary, a pricing supplement, that will contain specific information about the terms of the offer. The prospectus supplement and any pricing supplement may also add, update or change information contained in this prospectus.

You should read this prospectus, the prospectus supplement and any pricing supplement together with the additional information described under the heading “Where You Can Find More Information.”

The information contained in this document speaks only as of the date of this document unless the information specifically indicates that another date applies. We have not authorized anyone to give any information or make any representation about us that is different from, or in addition to, those contained in this prospectus or in any of the materials that we have incorporated into this prospectus. If anyone does give you information of this sort, you should not rely on it.

If you are in a jurisdiction where offers to sell, or solicitations of offers to purchase, the securities offered by this document are unlawful, or if you are a person to whom it is unlawful to direct these types of activities, then the offer presented in this document does not extend to you.

Unless otherwise indicated or unless the context requires otherwise, all references in this prospectus to “First Guaranty Bancshares,” the “Company,” “we,” “us,” “our” or similar references mean First Guaranty Bancshares, Inc., and references to the “Bank” mean First Guaranty Bank.

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus, including the information incorporated by reference into this prospectus, contains a number of 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”). These statements may be identified by use of words such as “anticipate,” “believe,” “could,” “estimate,” “expect,” “intend,” “seek,” “may,” “outlook,” “plan,” “potential,” “predict,” “project,” “should,” “will,” “would” and similar terms and phrases, including references to assumptions.

Forward-looking statements are based upon various assumptions and analyses made by First Guaranty Bancshares in light of management’s experience and its perception of historical trends, current conditions and expected future developments, as well as other factors it believes appropriate under the circumstances. Although we believe that our plans, intentions and expectations as reflected in these forward-looking statements are reasonable, we can give no assurance that these plans, intentions or expectations will be achieved or realized. These statements are not guarantees of future performance and are subject to risks, uncertainties and other factors, many of which are beyond the Company’s control, that could cause actual conditions or results to differ materially from those expressed or implied by such forward-looking statements. These factors include, without limitation, the following:

In addition, we routinely evaluate opportunities to expand through acquisitions and periodically conduct due diligence activities in connection with such opportunities. As a result, acquisition discussions and, in some cases, negotiations, may take place at any time, and acquisitions involving cash or our debt or equity securities may occur.

We assume no obligation for updating our forward-looking statements at any time. When considering these forward-looking statements, you should keep in mind these risks and uncertainties, as well as the other cautionary statements made in this prospectus and the prospectus supplements. You should not place undue reliance on any forward-looking statement, which speaks only as of the date made. You should refer to our periodic and current reports filed with the SEC for specific risks that could cause actual results to be significantly different from those expressed or implied by these forward-looking statements. See “Where You Can Find More Information” and “Risk Factors” below.

WHERE YOU CAN FIND MORE INFORMATION

This prospectus incorporates important business and financial information about First Guaranty Bancshares from documents filed with the SEC, with which we file registration statements, periodic reports, proxy statements, and other information. Our SEC filings are available over the Internet, at no cost, from the SEC’s website at www.sec.gov and from our website at www.fgb.net under the heading “Investor Relations.” You may also read and copy any document we file by visiting the SEC’s public reference room at 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further information about the public reference room.

This prospectus is part of a registration statement that we filed with the SEC. The registration statement contains more information than this prospectus regarding us, including certain exhibits and schedules. You can obtain a copy of the registration statement from the SEC at the address listed above or from the SEC’s website.

Except as specifically incorporated by reference into this prospectus, information on the websites listed above is not a part of this prospectus. You should rely only on the information contained in, or incorporated by reference into, this document. No one has been authorized to provide you with information that is different from that contained in, or incorporated by reference into, this document. This document is dated November 14, 2017, and you should assume that the information in this document is accurate only as of such date. You should assume that the information incorporated by reference into this document is accurate only as of the date of such incorporated document.

INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

The SEC allows us to incorporate information into this prospectus by reference to another document separately filed with the SEC. The information incorporated by reference is considered to be a part of this prospectus, except for any information that is superseded by information that is included directly in this document or in a more recent incorporated document. The information incorporated by reference contains information about us and our financial condition and is an important part of this prospectus.

This prospectus incorporates by reference the documents listed below that we have previously filed with the SEC.

In addition, we also incorporate by reference all future documents that we file with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of our initial registration statement relating to the securities covered by this prospectus until the completion of the distribution of such securities. These documents include periodic reports, such as annual reports on Form 10-K, quarterly reports on Form 10-Q, and current reports on Form 8-K (other than current reports furnished under Items 2.02 or 7.01 of Form 8-K, including any financial statements or exhibits relating thereto furnished pursuant to Item 9.01), as well as proxy statements.

You can obtain any of the documents incorporated by reference into this document through us, or from the SEC through the SEC’s website at www.sec.gov . Documents incorporated by reference are available from us without charge, excluding any exhibits to those documents, unless the exhibit is specifically incorporated by reference as an exhibit in this prospectus. You can obtain documents incorporated by reference into this prospectus from us by requesting them in writing or by telephone using the following contact information:

First Guaranty Bancshares, Inc.
400 East Thomas Street
Hammond, Louisiana 70401
Attention: Eric J. Dosch
(985) 375-0308

In addition, we maintain a corporate website, www.fgb.net under the heading “Investor Relations.” We make available, through our website, our annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K, and any amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d)

of the Exchange Act as soon as reasonably practicable after we electronically file such material with, or furnish it to, the SEC. This reference to our website is for the convenience of investors as required by the SEC and shall not be deemed to incorporate any information on the website into this prospectus or the registration statement of which this prospectus is a part.

Subordinated Debt Securities

Subordinated debt securities will be issued under the subordinated debt indenture. Payment of the principal, premium, if any, and interest on the subordinated debt securities will be subordinate and junior in priority of payment to prior payment in full of all of our senior indebtedness, including senior debt securities and other debt to the extent described in a prospectus supplement.

Unless otherwise stated in the applicable prospectus supplement, it is currently intended that the subordinated debt securities will qualify as Tier 2 Capital under the guidelines established by the Board of Governors of the Federal Reserve System (the “Federal Reserve”) for bank holding companies. The guidelines set forth specific criteria for subordinated debt to qualify as Tier 2 Capital. Among other things, the subordinated debt must:

Terms of Each Series of Debt Securities to be Provided Supplementally

A prospectus supplement and any supplemental indenture relating to any series of debt securities being offered will include specific terms relating to the offering. These terms will include some or all of the following:

We may issue debt securities under the indentures as “discount securities,” which means they may be offered and sold at a discount below their stated principal amount. These debt securities, as well as other debt securities that are not issued at a discount, may, for U.S. federal income tax purposes, be treated as if they were issued with “original issue discount,” because of interest payment and other characteristics. Special U.S. federal income tax considerations applicable to debt securities issued with original issue discount will be described in more detail in any applicable prospectus supplement.

The applicable prospectus supplement will also set forth the securities exchange or quotation system on which debt securities are listed or quoted, if any.

Provisions Contained in the Indentures

Global Securities

We may issue the debt securities of a series in whole or in part in the form of one or more fully registered global securities that we will deposit with a depositary or with a nominee for a depositary identified in the applicable prospectus supplement and registered in the name of such depositary or nominee. In such case, we will issue one or more registered global securities denominated in an amount equal to the aggregate principal amount of all of the debt securities of the series to be issued and represented by such registered global security or securities. Unless and until it is exchanged in whole or in part for debt securities in definitive registered form, a registered global security may not be transferred except as a whole by the depositary for such registered global security to its nominee; by a nominee of the depositary to the depositary or another nominee of the depositary; or by the depositary or its nominee to a successor of the depositary or a nominee of the successor.

The prospectus supplement relating to a series of debt securities will describe the specific terms of the depositary arrangement with respect to any portion of such series represented by a registered global security.

Conversion or Exchange Rights

Debt securities that we issue may be convertible into or exchangeable for our other securities or property. The terms and conditions of conversion or exchange will be set forth in the applicable prospectus supplement. The terms will include, among others, the following:

Information Concerning the Indenture Trustee

Under provisions of the indentures and the Trust Indenture Act of 1939, as amended (the “Trust Indenture Act”), if a trustee has or acquires a conflicting interest within the meaning of the Trust Indenture Act, the trustee

will either eliminate such interest or resign in the manner provided by the indentures. Any resignation will require the appointment of a successor trustee under the applicable indenture in accordance with its terms and conditions.

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

Each indenture contains certain limitations on the rights of the trustee, in the event that it becomes our creditor, to obtain payment of claims in some cases, or to realize on property received in respect of any such claim, as security or otherwise.

No Individual Liability of Officers, Directors, Employees or Shareholders

The indentures provide that none of our officers, directors, employees or shareholders will have any liability for any of our obligations under the indentures or the debt securities or for any claim based on, inspect of, or by reason of such obligations or their creation. Each holder of debt securities, by accepting a debt security, waives and releases all such liability. The waiver and release are part of the consideration for the issuance of the debt securities.

Legal Defeasance

We may deposit with the trustee, in trust, cash or U.S. government securities in an amount that, through the payment of interest and principal in accordance with their terms, will provide, not later than one day before the due date of any payment of money, an amount in cash, which is sufficient to make all payments of principal and interest on, and any mandatory sinking fund payments in respect of, the debt securities of that series on the due dates for such payments in accordance with the terms of the indenture and those debt securities. If we make such a deposit, unless otherwise provided under the applicable series of debt securities, we will be discharged from any and all obligations in respect of the debt securities of such series (except for obligations relating to the transfer or exchange of debt securities and the replacement of stolen, lost or mutilated debt securities and relating to maintaining paying agencies and the treatment of funds held by paying agents and certain rights of the trustee and our obligations with respect thereto). However, this discharge may occur only if, among other things, we have delivered to the trustee a legal opinion 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, there has been a change in the applicable U.S. federal income tax law, in either case to the effect that, and, based thereon confirming 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.

Covenant Defeasance

Under the indentures (and unless otherwise provided by the terms of the applicable series of debt securities), upon making the deposit and delivering the legal opinion described above under “—Legal Defeasance,” we will not need to comply with certain covenants, including those described below under “—Consolidation, Merger or Asset Sale,” as well as any additional covenants that may be set forth in the applicable prospectus supplement, and any such noncompliance will not constitute a default or an event of default with respect to the debt securities of that series, or covenant defeasance.

If 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 amounts 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.

Satisfaction and Discharge

We may discharge our obligations under either indenture and the debt securities of a series (except for certain surviving rights of the trustee and our obligations in connection therewith) if: (a) all outstanding debt securities of that series and all other outstanding debt securities issued under such indenture (i) have been

delivered for cancellation, or (ii) (1) have become due and payable, (2) will become due and payable at their stated maturity within one year, (3) are to be called for redemption within one year under arrangements satisfactory to the trustee for the giving of notice and redemption by the trustee or (4) are deemed paid and discharged in a legal defeasance described above (and in the case of clauses (1), (2) and (3), we have irrevocably deposited with the trustee an amount sufficient to pay and discharge the principal of (and premium, if any), and interest on all outstanding debt securities and any other sums due on the stated maturity date or redemption date, as the case may be); (b) we have paid all other sums payable by us under such indenture; and (c) we have delivered an officers’ certificate and opinion of counsel confirming.

Consolidation, Merger or Asset Sale

The indentures provide that 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, and we may not permit any other person to consolidate with or merge into us or to convey, transfer or lease all or substantially all of its properties and assets to us, unless the following conditions are satisfied:

The remaining or acquiring person, association or entity will be substituted for us in the indentures with the same effect as if it had been an original party to the indentures. Thereafter, the successor may exercise our rights and powers under the indentures, in our name or in its own name. If we sell or transfer all or substantially all of our assets, we will be released from all our liabilities and obligations under any indenture and under the debt securities. If we lease all or substantially all of our assets, we will not be released from our obligations under the indentures.

Events of Default and Remedies

For any series of debt securities, an event of default will include the following events:

An event of default for a particular series of debt securities does not necessarily constitute an event of default for any other series of debt securities issued under the indentures.

If an event of default with respect to any outstanding debt securities occurs and is continuing, then the trustee or the holders of 25% of the aggregate principal amount of the outstanding debt securities of that series

may, by written notice to us (and to the trustee if given by the holders), accelerate the payment of 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. Such acceleration is automatic, without any notice required, in the case of an event of default resulting from certain events of bankruptcy, insolvency or reorganization.

At any time after acceleration with respect to debt securities of any series, but before the trustee has obtained a court judgment or decree for payment of the amounts due, the holders of a majority of the aggregate 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 that have become due solely by such declaration of acceleration, have been cured or waived as provided in the indenture. The prospectus supplement relating to any series of debt securities that are discount securities will contain particular provisions relating to acceleration of a portion of the principal amount of such discount securities upon the occurrence of an event of default.

The indentures provide that the trustee will be under no obligation to exercise any rights or powers under such indenture at the request of any holder of outstanding debt securities unless the trustee is indemnified to its satisfaction against any loss, liability or expense. Subject to certain rights of the trustee, the holders of a majority of the aggregate 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 may institute any proceeding, judicial or otherwise, with respect to the indenture 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, premium 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.

Under the indentures we must furnish the trustee a statement as to compliance with such indenture within 120 days after the end of our fiscal year (beginning with the fiscal year ending immediately following the execution of such indenture). The indentures provide that, other than with respect to payment defaults, the trustee may withhold notice to the holders of debt securities of any series of a default or event of default if it in good faith determines that withholding notice is in the interests of the holders of those debt securities.

Modification of Indentures

Each indenture provides that we and the trustee may, without the consent of the holders of our debt securities, enter into supplemental indentures to:

Each indenture also provides that we and the trustee may, with the consent of the holders of not less than a majority of the aggregate principal amount of outstanding debt securities of all series of senior debt securities or subordinated debt securities, as the case may be, then outstanding and affected thereby (voting as one class), add any provisions to, or change in any manner, eliminate or modify in any way the provisions of, the indenture or modify in any manner the rights of the holders of the debt securities. We and the trustee may not, however, without the consent of the holder of each outstanding debt security affected thereby:

Governing Law

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

regulatory consultation with respect to capital distributions in certain circumstances such as where the holding company’s net income for the past four quarters, net of dividends previously paid over that period, is insufficient to fully fund the dividend or the holding company’s overall rate or earnings retention is inconsistent with its capital needs and overall financial condition.

Liquidation

In the event of a liquidation or dissolution of First Guaranty Bancshares, holders of our common stock and any participating preferred stock will be entitled to receive, after payment or provision for payment of all of our debts and liabilities and the preferential rights of, and the payment of liquidation preferences, if any, on any outstanding shares of preferred stock, all of our assets available for distribution. If we issue preferred stock in the future, holders of such stock may have a senior interest over holders of common stock in such a distribution.

Preemptive Rights

Holders of the common stock of First Guaranty Bancshares are not entitled to preemptive rights with respect to any shares that may be issued. Our common stock is not subject to redemption.

Restrictions on Acquisition of First Guaranty Bancshares

The following is a general summary of the material provisions of our restated articles of incorporation and bylaws and the Louisiana Business Corporation Act that may have an “anti-takeover effect.” Such provisions might discourage future takeover attempts by impeding efforts to acquire us or stock purchases in furtherance of such an acquisition.

Authorized Shares of Capital Stock. Our restated articles of incorporation authorizes the issuance of up to 100,600,000 shares of common stock and up to 100,000 shares of preferred stock. Shares of preferred stock with voting rights could be issued and would then represent an additional class of stock required to approve any proposed acquisition. This preferred stock, together with authorized but unissued shares of our common stock, could represent additional capital required to be purchased by an acquiror. Issuance of such additional shares may also dilute the voting interest of our shareholders.

Generally, the Louisiana Business Corporation Act does not require shareholder approval for an issuance of authorized shares. However, the Louisiana Business Corporation Act does require shareholder approval of non-cash share issuances in excess of 20% of a corporation’s total voting power on a pre-transaction basis. In addition, the listing requirements of the NASDAQ Stock Market, which would apply so long as our common stock were listed on such Market, require shareholder approval of certain issuances equal to or exceeding 20% of the then outstanding voting power or the then outstanding number of shares of common stock, but not a public offering of common stock for cash.

Directors. The board of directors has the power to fill board vacancies, whether occurring by reason of an increase in the number of directors or by resignation, death, removal or otherwise, although the shareholders may fill vacancies at a special meeting called for that purpose before the board takes action. Our bylaws provide that, in general, any shareholder desiring to make a nomination for the election of directors must submit written notice not less than 45 days or more than 90 days in advance of the meeting. The shareholders, by the affirmative vote of the holders of a majority of the outstanding shares of stock entitled to vote at an annual or special meeting of shareholders or by written consent of holders of a majority of shares outstanding, have the power to remove any and all directors at any time, with or without cause.

Actions by Shareholders. Our bylaws provide that special meetings of the shareholders may be called only by a majority of the board of directors, the President, Chairman, or Chief Executive Officer, or the President or Secretary at the written request of the holders of at least one-fifth of all shares entitled to vote. The bylaws provide that notice of shareholder proposals for new business to be considered at an annual meeting must be submitted, in general, not less than 30 or more than 90 days before the meeting.

Under the Louisiana Business Corporation Act, any amendment of our restated articles of incorporation and any merger or other business combination that requires shareholder approval or statutory share exchange to which we are a party requires the approval of a majority of the shares entitled to be cast at the meeting of shareholders. In addition, the Louisiana Business Corporation Act also provides that if any class or series of shares is entitled to vote as a separate group on a plan of merger or share exchange, the approval of a majority of such separate voting group is required.

The board of directors may amend the Company’s bylaws without shareholder approval.

Indemnification. Our restated articles of incorporation and bylaws provide generally that we will indemnify and hold harmless, to the fullest extent permitted by Louisiana law, our directors and officers, as well as other persons who have served as directors, officers, fiduciaries or in other representative capacities, serving at our request in connection with any actual or threatened action, proceeding or investigation, subject to limited exceptions. To the extent that indemnification for liabilities arising under the Securities Act may be permitted to our directors, officers and controlling persons, we have been advised that, in the opinion of the SEC, this indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable. Finally, our ability to provide indemnification to our directors and officers is limited by federal banking laws and regulations.

Limitation of liability. Our restated articles of incorporation limit the personal liability of our directors in actions brought on our behalf or on behalf of our shareholders for monetary damages as a result of a director’s acts or omissions while acting in a capacity as a director, with certain exceptions. Our restated articles of incorporation do not eliminate or limit our right or the right of our shareholders to seek injunctive or other equitable relief not involving monetary damages.

In addition, unless the applicable prospectus supplement indicates otherwise, we will have the right to “reopen” a previous issue of a series of preferred stock by issuing additional preferred stock of such series.

We may, at our option, with respect to any series of the preferred stock, elect to offer fractional interests in shares of preferred stock, which we call depositary shares. See “Description of Depositary Shares” below.

Rank

With respect to the payment of dividends and the priority of payments upon liquidation, winding up and dissolution, unless otherwise specified in the applicable prospectus supplement, each series of preferred stock generally will rank senior to all classes of common stock and equally with each other series of preferred stock. The rights of holders of shares of each series of preferred stock will be subordinate to those of our general creditors.

Dividends

The holders of the preferred stock of each series will be entitled to receive cash dividends out of funds legally available, when, as and if declared by the board of directors, at the rates and on the dates stated in the applicable prospectus supplement. These rates may be fixed or variable. If the dividend rate is variable, the applicable prospectus supplement will describe the formula used to determine the dividend rate for each dividend period. We will pay dividends to the holders of record as they appear on our stock books on the applicable record dates. Unless the applicable prospectus supplement indicates otherwise, dividends on any series of preferred stock will be cumulative.

The board will not declare and pay a dividend on any of our stock ranking as to dividends, equal with or junior to the preferred stock unless full dividends on the preferred stock have been declared and paid (or declared and sufficient money set aside for payment).

Until dividends are paid in full or declared and set aside for payment on any series of preferred stock ranking equal with the preferred stock as to dividends:

We will not pay interest, or money in lieu of interest, for any dividend payments on any series of the preferred stock that are in arrears.

Rights Upon Liquidation

If we voluntarily or involuntarily liquidate, dissolve or wind up our business, the holders of shares of each series of preferred stock and any other securities that have rights equal to that series of preferred stock under these circumstances, will be entitled to receive out of our assets that are available for distribution to shareholders:

Neither the sale of all or any part of our property and business, nor our merger into or consolidation with any other corporation, nor the merger or consolidation of any other corporation with or into us, will be deemed to be a dissolution, liquidation or winding up.

If our assets are insufficient to pay all amounts to which holders of preferred stock are entitled, we will make no distribution on the preferred stock or on any other securities ranking equal to the preferred stock unless we make a pro rata distribution to those holders. After we pay the full amount of the liquidation distribution to which the holders are entitled, the holders will have no right or claim to any of our remaining assets.

Because we are a holding company, our rights, the rights of our creditors and of our shareholders, including the holders of the preferred stock offered by this prospectus, to participate in the assets of any subsidiary upon the subsidiary’s liquidation or recapitalization may be subject to the prior claims of the subsidiary’s creditors except to the extent that we may ourselves be a creditor with recognized claims against the subsidiary.

Redemption

A series of the preferred stock may be redeemable, in whole or in part, at our option, and may be subject to mandatory redemption under a sinking fund or otherwise as described in the applicable prospectus supplement. The preferred stock that we redeem will be restored to the status of authorized but unissued shares of preferred stock that we may issue in the future.

If a series of preferred stock is subject to mandatory redemption, the applicable prospectus supplement will specify the number of shares that we will redeem in each year and the redemption price per share together with an amount equal to all accrued and unpaid dividends on those shares to the redemption date. The applicable prospectus supplement will state whether the redemption price can be paid in cash or other property. If the redemption price is to be paid only from the net proceeds of issuing our capital stock, the terms of the series of preferred stock may provide that, if the capital stock has not been issued or if the net proceeds are not sufficient to pay the full redemption price then due, the shares relating to series of the preferred stock will automatically and mandatorily be converted into shares of our capital stock under the conversion provisions of the applicable prospectus supplement.

If fewer than all of the outstanding shares of any series of the preferred stock are to be redeemed, the redemption will be made in a manner that the board of directors decides is equitable.

Unless we default in the payment of the redemption price, dividends will cease to accrue after the redemption date on shares of preferred stock called for redemption and all rights of holders of such shares will terminate except for the right to receive the redemption price.

Voting Rights

Holders of preferred stock generally will not have voting rights except in certain limited circumstances, although the board of directors may provide voting rights for any newly created series of preferred stock. The holders of shares of preferred stock will have no voting rights, except as otherwise stated in the applicable prospectus supplement; as otherwise stated in the applicable amendment to the restated articles of incorporation establishing such series; or as required by applicable law.

Under Federal Reserve regulations, if the holders of any series of preferred stock become entitled to vote for the election of directors, that series may then be considered a class of voting securities. A holder of 25% or more of a series may then be subject to regulation as a bank holding company under the Bank Holding Company Act. In addition, at the time that the series are deemed a class of voting securities, any bank holding company may be required to obtain the prior approval of the Federal Reserve in order to acquire more than 5% of that series and any person other than a bank holding company may be required to obtain the approval of the Federal Reserve to acquire 10% or more of that series.

Conversion or Exchange Rights

The terms on which shares of preferred stock of any series may be converted into or exchanged for another class or series of securities will be described in the applicable prospectus supplement.

Transfer Agent

The transfer agent, registrar, dividend disbursing agent and redemption agent for shares of each series of preferred stock will be named in the prospectus supplement relating to such series.

will be the same date as the record date for the preferred stock. Each record holder of the depositary shares on the record date will be entitled to instruct the depositary as to the exercise of the voting rights pertaining to the number of shares of preferred stock represented by that holder’s depositary shares. The depositary will endeavor, insofar as practicable, to vote the number of shares of preferred stock represented by the depositary shares in accordance with those instructions, and we will agree to take all action that may be deemed necessary by the depositary in order to enable the depositary to do so. The depositary will not vote any shares of preferred stock except to the extent it receives specific instructions from the holders of depositary shares representing that number of shares of preferred stock.

Charges of Depositary

We will pay all transfer and other taxes and governmental charges arising solely from the existence of the depositary arrangements. We will pay charges of the depositary in connection with the initial deposit of the preferred stock and any redemption of the preferred stock. Holders of depositary receipts will pay other transfer and other taxes and governmental charges and such other charges as are expressly provided in the deposit agreement to be for their accounts.

Resignation and Removal of Depositary

The depositary may resign at any time by delivering to us notice of its election to do so, and we may remove the depositary at any time. Any resignation or removal of the depositary will take effect upon our appointment of a successor depositary and its acceptance of such appointment. The successor depositary must be appointed within 60 days after delivery of the notice of resignation or removal and must be a bank or trust company having its principal office in the United States and having a combined capital and surplus of at least $50,000,000.

Notices

The depositary will forward to holders of depositary receipts all notices, reports and other communications, including proxy solicitation materials received from us, which are delivered to the depositary and that we are required to furnish to the holders of the preferred stock.

Limitation of Liability

Neither we nor the depositary will be liable if either of us is prevented or delayed by law or any circumstance beyond our control in performing our obligations. Our obligations and those of the depositary will be limited to performance in good faith of our and their duties thereunder. We and the depositary will not be obligated to prosecute or defend any legal proceeding in respect of any depositary shares or preferred stock unless satisfactory indemnity is furnished. We and the depositary may rely upon written advice of counsel or accountants, on information provided by persons presenting preferred stock for deposit, holders of depositary receipts or other persons believed to be competent and on documents believed to be genuine.

Description of Purchase Contracts

We may issue purchase contracts, including purchase contracts issued as part of a unit with one or more other securities, for the purchase or sale of our debt securities, preferred stock, depositary shares or common stock. The price of our debt securities or price per share of common stock, preferred stock or depositary shares, as applicable, may be fixed at the time the purchase contracts are issued or may be determined by reference to a specific formula contained in the purchase contracts. We may issue purchase contracts in such amounts and in as many distinct series as we wish.

The applicable prospectus supplement may contain, where applicable, the following information about the purchase contracts issued under it:

The applicable prospectus supplement will describe the terms of any purchase contracts. The preceding description and any description of purchase contracts in the applicable prospectus supplement does not purport to be complete and is subject to and is qualified in its entirety by reference to the purchase contract agreement and, if applicable, collateral arrangements and depositary arrangements relating to such purchase contracts.

forth in the applicable prospectus supplement. Upon the expiration date, the subscription rights will expire and will no longer be exercisable, unless, in our sole discretion prior to the expiration date, we extend the subscription rights offering.

Exercise Price

Our board of directors will determine the exercise price or prices for the subscription rights based upon a number of factors, including, without limitation, our business prospects; our capital requirements; the price or prices at which an underwriter or standby purchasers may be willing to purchase securities that remain unsold in the subscription rights offering; and general conditions in the securities markets, especially for securities of financial institutions.

The subscription price may or may not reflect the actual or long-term fair value of the common stock, preferred stock or debt securities offered in the subscription rights offering. We provide no assurances as to the market values or liquidity of any subscription rights issued, or as to whether or not the market prices of the common stock, preferred stock or debt securities subject to the subscription rights will be more or less than the subscription rights’ exercise price during the term of the rights or after the rights expire.

Exercising Rights; Fees and Expenses

The manner of exercising subscription rights will be set forth in the applicable prospectus supplement. Any subscription agent or escrow agent will be set forth in the applicable prospectus supplement. We will pay all fees charged by any subscription agent and escrow agent in connection with the distribution and exercise of subscription rights. Subscription rights holders will be responsible for paying all other commissions, fees, taxes or other expenses incurred in connection with their transfer of subscription rights that are transferable. Neither we nor the subscription agent will pay such expenses.

Expiration of Rights

The applicable prospectus supplement will set forth the expiration date and time (“Expiration Date”) for exercising subscription rights. If holders of subscription rights do not exercise their subscription rights prior to such time, their subscription rights will expire and will no longer be exercisable and will have no value.

We will extend the Expiration Date as required by applicable law and may, in our sole discretion, extend the Expiration Date. If we elect to extend the Expiration Date, we will issue a press release announcing such extension prior to the scheduled Expiration Date.

Withdrawal and Termination

We may withdraw the subscription rights offering at any time prior to the Expiration Date for any reason. We may terminate the subscription rights offering, in whole or in part, at any time before completion of the subscription rights offering if there is any judgment, order, decree, injunction, statute, law or regulation entered, enacted, amended or held to be applicable to the subscription rights offering that in the sole judgment of our board of directors would or might make the subscription rights offering or its completion, whether in whole or in part, illegal or otherwise restrict or prohibit completion of the subscription rights offering. We may waive any of these conditions and choose to proceed with the subscription rights offering even if one or more of these events occur. If we terminate the subscription rights offering, in whole or in part, all affected rights will expire without value, and all subscription payments received by the subscription agent will be returned promptly without interest.

Rights of Subscribers

Holders of subscription rights will have no rights as holders with respect to our common stock, preferred stock or debt securities for which the rights may be exercised until they have exercised their rights by payment in full of the exercise price and in the manner provided in the applicable prospectus supplement, and such common stock, preferred stock or debt securities, as applicable, have been issued to such persons. Holders of subscription rights will have no right to revoke their subscriptions or receive their monies back after they have completed and delivered the materials required to exercise their subscription rights and have paid the exercise price to the subscription agent. All exercises of rights will be final and cannot be revoked by the holder of rights.

Regulatory Limitations

We will not be required to issue any person or group of persons shares of our common stock, preferred stock or debt securities pursuant to the subscription rights offering if, in our sole opinion, such person would be required to give prior notice to or obtain prior approval from, any state or federal governmental authority to own or control such securities if, at the time the rights offering is scheduled to expire, such person has not obtained such clearance or approval in form and substance reasonably satisfactory to us.

Standby Agreements

We may enter into one or more separate agreements with one or more standby underwriters or other persons to purchase, for their own account or on our behalf, our common stock, preferred stock or debt securities not subscribed for in the subscription rights offering. The terms of any such agreements will be described in the applicable prospectus supplement.

PLAN OF DISTRIBUTION

We may sell our securities through underwriters or dealers, directly to purchasers, through agents, or through any combination thereof.

Each time that we use this prospectus to sell our securities, we will also provide a prospectus supplement that contains the specific terms of the offering. The prospectus supplement will set forth the terms of the offering of such stock, including:

If underwriters are used in the sale of any securities on a firm commitment basis, the securities will be acquired by the underwriters for their own account and may be resold from time to time in one or more transactions, including negotiated transactions, at a fixed public offering price or at varying prices determined at the time of sale. The securities may be either offered to the public through underwriting syndicates represented by managing underwriters, or directly by underwriters. Generally, the underwriters’ obligations to purchase the securities will be subject to certain conditions precedent. The underwriters will be obligated to purchase all of the securities if they purchase any of the securities.

To the extent that we make sales to or through one or more underwriters or agents in at-the-market offerings, we will do so pursuant to the terms of a distribution agreement between us and the underwriters or agents. If we engage in at-the-market sales pursuant to a distribution agreement, we will issue and sell shares of our common stock to or through one or more underwriters or agents, which may act on an agency basis or on a principal basis. During the term of any such agreement, we may sell shares on a daily basis in exchange transactions or otherwise as we agree with the underwriters or agents. The distribution agreement will provide that any shares of our common stock sold will be sold at prices related to the then prevailing market prices for our common stock. Therefore, exact figures regarding proceeds that will be raised or commissions to be paid cannot be determined at this time and will be described in a prospectus supplement. Pursuant to the terms of the distribution agreement, we also may agree to sell, and the relevant underwriters or agents may agree to solicit offers to purchase, blocks of our common stock or other securities. The terms of each such distribution agreement will be set forth in more detail in a prospectus supplement to this prospectus. If any underwriter or agent acts as principal, or broker dealer acts as underwriter, it may engage in certain transactions that stabilize, maintain or otherwise affect the price of our securities. We will describe any such activities in the prospectus supplement relating to the transaction.

We may sell the securities through agents from time to time. The prospectus supplement will name any agent involved in the offer or sale of our securities and any commissions we pay to them. Generally, any agent will be acting on a best efforts basis for the period of its appointment.

We may authorize underwriters, dealers or agents to solicit offers by certain purchasers to purchase our securities at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a specified date in the future. The contracts will be subject only to those conditions set forth in the prospectus supplement, and the prospectus supplement will set forth any commissions or discounts we pay for solicitation of these contracts.

Agents and underwriters may be entitled to indemnification by us against certain civil liabilities, including liabilities under the Securities Act, or to contribution with respect to payments that the agents or underwriters may be required to make in respect thereof. Agents and underwriters may be customers of, engage in transactions with, or perform services for us in the ordinary course of business.

We may enter into derivative transactions with third parties, or sell securities not covered by this prospectus to third parties in privately negotiated transactions. If the applicable prospectus supplement indicates, in connection with those derivatives, the third parties may sell securities covered by this prospectus and the applicable prospectus supplement, including in short sale transactions. If so, the third party may use securities

pledged by us or borrowed from us or others to settle those sales or to close out any related open borrowings of stock, and may use securities received from us in settlement of those derivatives to close out any related open borrowings of securities. The third party in such sale transactions will be an underwriter and will be identified in the applicable prospectus supplement (or a post-effective amendment).

LEGAL OPINION

The validity of the securities offered hereby will be passed upon for us by Luse Gorman, PC, Washington, D.C.

EXPERTS

The consolidated financial statements of First Guaranty Bancshares, Inc. as of December 31, 2016 and 2015, and for each of the three years in the period ended December 31, 2016, have been audited by Castaing, Hussey & Lolan, LLC, an independent registered public accounting firm, as set forth in their report appearing in our Annual Report on Form 10-K for the fiscal year ended December 31, 2016 and incorporated herein by reference. Such consolidated financial statements have been so incorporated in reliance upon the report of such firm given upon their authority as experts in accounting and auditing.

FIRST GUARANTY BANCSHARES, INC.

Up to $25,000,000

Common Stock

PROSPECTUS SUPPLEMENT

(To the Prospectus dated November 14, 2017)

S ANDLER O’N EILL + P ARTNERS , L.P.

November 20, 2017