Third Coast Bancshares (TCBX) S-4Registration of securities issued in business combination transactions

This prospectus is part of a Registration Statement on Form(the “registration statement”) that we have filed with the SEC under the Securities Act. This prospectus does not contain all the information set forth in the registration statement, certain parts of which are omitted in accordance with the rules and regulations of the SEC. For further information with respect to us, the exchange offer and the securities offered by this prospectus, reference is made to the registration statement, including the exhibits to the registration statement.

The registration statement of which this prospectus is a part, including the exhibits to the registration statement, contains additional information about us and the securities offered under this prospectus. The registration statement can be obtained at no cost from the SEC’s website (http://www.sec.gov). Copies of certain information filed by us with the SEC are also available on our website atat no cost. Information contained on, or accessible from, the Third Coast Bancshares, Inc. website is expressly not incorporated by reference into this prospectus, and you should not consider it part of this prospectus or any other filings we make with the SEC.

We are subject to the reporting requirements of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and therefore we file annual, quarterly and current reports, proxy statements, and other documents with the SEC. Our SEC filings are available to the public at no cost on the SEC’s website at. We also maintain a website at. The reference to our website is not intended to be an active link and the information on, or that can be accessed through, our website is not, and you must not consider the information to be, a part of this prospectus or any other filings we make with the SEC.

We have filed with the SEC a registration statement on Formrelating to the New Notes and the exchange offer. This prospectus is a part of the registration statement and, as permitted by SEC rules, does not contain all of the information in the registration statement. The registration statement, including the exhibits thereto contains additional relevant information about us, the New Notes and the exchange offer.

Holders of the Old Notes can obtain any of the other documents listed above from the SEC at no cost at the SEC’s website (), or they may request a copy of these filings, also at no cost, by contacting us at the following address or telephone number:

FRBNY reports that SOFR is calculated as a volume-weighted median of transaction-levelparty repo data collected from The Bank of New York Mellon, which currentlyU.S. Treasury repo transactions cleared through the FICC’s delivery-versus-payment service.

Dividend payments from the Bank would also be prohibited under the “prompt corrective action” regulations of federal bank regulators if the Bank is, or after payment of such dividends would be, undercapitalized under such regulations. In addition, the Bank is subject to restrictions under federal law that limit its ability to transfer funds or other items of value to us and oursubsidiaries, including affiliates, whether in the form of loans and other extensions of credit, investments and asset purchases, or as other transactions involving the transfer of value. Unless an exemption applies, these transactions by the Bank with us are limited to 10% of the Bank’s capital stock and surplus and, with respect to all such transactions with affiliates in the aggregate, to 20% of the Bank’s capital stock and surplus. Moreover, loans and extensions of credit by the Bank to its affiliates, including us, generally are required to be secured in specified amounts. A bank’s transactions with itsaffiliates also are required generally to be onterms.

We will determine all questions as to the validity, form and eligibility (including time of receipt) of such withdrawal notices in our sole discretion, and our determination will be final and binding on all parties. Any Old Notes validly withdrawn will be considered not to have been validly tendered for purposes of the exchange offer, and no New Notes will be issued in exchange for such Old Notes. Any Old Notes that have been tendered but that are not accepted for exchange or that are withdrawn will be returned to the holder, without expense to such holder, after withdrawal, rejection of tender or termination of the exchange offer. Validly withdrawn Old Notes may beby following one of the procedures described above under “—” at any time prior to the expiration date of the exchange offer.

For additional information, you may contact the exchange agent by calling (713)or emailing Mauri.Cowen@umb.com.

We will pay the exchange agent reasonable and customary fees for its services (including attorneys’ fees) and will reimburse it for its reasonableexpenses in connection with the exchange offer.

the interest rate on the Old Notes will be increased by 0.25% per annum immediately following suchperiod the date of such registration default and will increase by an additional 0.25% per annum immediately following eachperiod during which additional interest accrues, but in no event will such increase exceed 0.50% per annum. If at any time more than one registration default has occurred and is continuing, the increase in

On March 31, 2022, we issued $82,250,000 in aggregate principal amount of our 5.500%Rate Subordinated Notes due 2032 which we refer to in this prospectus as the Old Notes. The Old Notes were issued in private placement transactions to certain qualified institutional buyers and institutional accredited investors and, as such, were not registered under the Securities Act. The Old Notes were issued under the indenture, dated March 31, 2022, by and between Third Coast Bancshares, Inc., as issuer, and UMB Bank, N.A., as trustee, which we refer to as the indenture. The term “notes” refers collectively to the Old Notes and the New Notes.

From and including March 31, 2022 to but excluding April 1, 2027 or any earlier redemption date, the New Notes will bear interest at a fixed annual rate equal to 5.500%, payable semi-annually in arrears on April 1 and October 1 of each year, beginning October 1, 2022. During this period, interest will be computed on the basis of ayear consisting of twelvemonths. If the due date for any payment of principal or interest falls on a day that is not a business day, the payment of interest and principal will be made on the next succeeding business day, and no interest on such payment shall accrue for the period from and after the scheduled due date.

From, and including, April 1, 2027 to, but excluding, April 1, 2032 unless redeemed prior to April 1, 2032 (such period, the “floating rate period”), the New Notes will bear interest at a rate equal to Three-Month Term SOFR, reset quarterly, plus 315 basis points, or such other rate as determined pursuant to the indenture, payable quarterly in arrears on January 1, April 1, July 1, and October 1 of each year through the stated Maturity Date or earlier redemption date. If Three-Month Term SOFR (or other applicable floating interest rate) is less than zero, then Three-Month Term SOFR (or other such applicable floating interest rate) shall be deemed to be zero. During this period, interest will be computed on the basis of ayear and the actual number of days elapsed, and will be payable quarterly in arrears on January 1, April 1, July 1, and October 1 of each year commencing on July 1, 2027. See “–Definitions Relating to the Determination of the Floating Interest Rate” and “—Effect of Benchmark Transition Event” below for the definition of Three-Month Term SOFR, a description of the method of its determination, and the alternative methods for determining the applicable floating interest rate for the notes in the event that a Benchmark Transition Event and its related Benchmark Replacement Date have occurred with respect to Three-Month Term SOFR on or prior to the Reference Time (in each case, as defined below).

“Three-Month Term SOFR” means the rate for Term SOFR for a tenor of three months that is published by the Term SOFR Administrator at the Reference Time for any Floating Rate Period, as determined by the Calculation Agent after giving effect to the Three-Month Term SOFR Conventions. All percentages used in or resulting from any calculation of Three-Month Term SOFR shall be rounded, if necessary, to the nearestof a percentage point, with 0.000005% rounded up to 0.00001%.

Upon our termination,liquidation or reorganization, whether in bankruptcy, insolvency, reorganization or receivership proceedings or upon an assignment for the benefit of our creditors or any other marshalling of our assets and liabilities or otherwise, holders of all of our Senior Indebtedness will first be entitled to receive payment in full in accordance with the terms of such Senior Indebtedness of the principal of, and premium, if any, and interest on (including interest accruing subsequent to the commencement of any proceeding for our bankruptcy or reorganization under any applicable bankruptcy, insolvency or similar law), that Senior Indebtedness before any payment is made on the notes. If, after we have paid the Senior indebtedness in full, there are any amounts available for payment of the notes and any of our other indebtedness and obligations ranking equally in right of payment with the notes, then we will use such remaining assets to pay the amounts of principal of and premium, if any, and accrued and unpaid interest on the notes and such other of our indebtedness and obligations that rank equally in right of payment with the notes. If those assets are insufficient to pay in full the principal of and premium, if any, and interest on the notes and such other indebtedness and obligations, those assets will be applied ratably to the payment of such amounts owing with respect to the notes and such other indebtedness and obligations.

In the event that we are subject to any termination,liquidation or reorganization, whether in bankruptcy, insolvency, reorganization or receivership proceedings or upon an assignment for the benefit of our creditors or any other marshalling of our assets and liabilities or otherwise, if the holders of the notes receive for any reason any payment on the notes or other distributions of our assets with respect to the notes before all of our senior indebtedness is paid in full, the holders of the notes will be required to return that payment or distribution to the bankruptcy trustee, receiver, liquidating trustee, custodian, assignee, agent or other person making payment of our assets for all our senior indebtedness remaining unpaid until all that Senior Indebtedness has been paid in full, after giving effect to any other concurrent payment or distribution to the holders of such Senior Indebtedness.

Secondary trading in bonds and notes of corporate issuers is generally settled in clearinghouse (that is, next day) funds. In contrast, beneficial interests in a global notes usually trade in DTC’sfunds settlement system and settle in immediately available funds. We make no representations as to the effect that settlement in immediately available funds will have on trading activity in those beneficial interests.

Under the indenture, if we fail to pay any installment of interest on any note when such interest becomes due and payable, and such default continues for a period of 30 days, or if we fail to pay all or any part of the principal of any note when such principal becomes due and payable, the trustee may, subject to certain limitations and conditions, demand that we pay to the trustee, for the benefit of the holders of such notes, the whole amountand payable with respect to such notes, with interest upon the overdue principal and, to the extent permitted by applicable law, upon any overdue installments of interest at the rate or respective rates, as the case may be, provided for or with respect to such notes or, if no such rate or rates are so provided, at the rate or respective rates, as the case may be, of interest borne by such notes, and in addition thereto, such further amount of money as will be sufficient to cover the costs and expenses of collection.

Any rights to receive payment of such amounts under the notes remain subject to the subordination provisions of the notes as discussed above under “–Subordination.” Neither the trustee nor the holders of the notes will have the right to accelerate the maturity of the notes in the case of our failure to pay the principal of, or interest on, the notes or ourof any other covenant or warranty under the notes or the indenture.

The following is a summary of certain material United States federal income tax considerations of the exchange of outstanding Old Notes for New Notes in the exchange offer. It is not a complete analysis of all the potential tax considerations relating to the exchange of Old Notes for New Notes. This discussion is based upon the provisions of the Internal Revenue Code of 1986, as amended (the “Code”), existing, temporary and proposed Treasury regulations promulgated under the Code and published administrative and judicial interpretations thereof and rulings thereunder, all as currently in effect. These authorities are subject to change, possibly on a retroactive basis, and subject to differing interpretations. We cannot assure you that the Internal Revenue Service (the “IRS”), will not challenge one or more of the tax consequences described in this prospectus, and we have not obtained, and do not intend to obtain, a ruling from the IRS with respect to the United States federal income tax consequences described herein. Furthermore, this discussion does not address the tax considerations arising under the laws of any state, local orjurisdiction or any United States federaltax consequences of the exchange of Old Notes for New Notes.

This discussion is limited to the United States federal income tax consequences applicable to holders that purchased their Old Notes from us in private placements on March 31, 2022 at the offering price and who held Old Notes, and will now hold the New Notes, as “capital assets” within the meaning of Section 1221 of the Code (generally, property held for investment). This discussion does not address all United States federal income tax considerations that may be applicable to each holder’s particular circumstances or to holders that may be subject to special tax rules under United States federal income tax laws, including, but not limited to, (i) banks, insurance companies, thrifts, other financial institutions, mutual funds, or grantor trusts, (ii) regulated investment companies or, real estate investment trusts and shareholders of such entities,organizations, (iv) brokers, dealers or traders in securities, commodities or currencies, (v) United States expatriates, (vi) corporations treated as “personal holding companies,” subchapter S corporations, controlled foreign corporations or, passive foreign investment companies, (vii) persons subject to the alternative minimum tax, (viii) traders in securities that elect to use amethod of accounting for their securities holdings, (ix) United States holders whose functional currency is not the United States dollar, (x) persons that will hold the New Notes as a position in a hedging transaction, straddle or conversion transaction or as part of a “synthetic security,” other integrated transactions or risk reduction transaction, (xi) persons deemed to sell the Old Notes under the constructive sale provisions of the Code, (xii) an accrual method taxpayer who is required to recognize income for United States federal income tax purposes no later than when such income is taken into account for financial accounting purposes, (xiii) a person that purchases or sells notes as part of a wash sale for tax purposes, (xiv) retirement plans, individual plans, individual retirement accounts andaccounts, or (xv) entities or arrangements classified as partnerships for United States federal income tax purposes or other pass-through entities, or investors in such entities.

We will not receive any proceeds from any sale of New Notes by broker-dealers or any other persons. New Notes received by broker-dealers for their own account pursuant to the exchange offer may be sold from time to time in one or more transactions in themarket, in negotiated transactions, through the writing of options on New Notes or a combination of such methods of resale, at market prices prevailing at the time of resale, at prices related to such prevailing market prices or at negotiated prices. Any such resale may be made directly to purchasers or to or through brokers or dealers who may receive compensation in the form of commissions or concessions from any such broker-dealer and/or the purchasers of any New Notes. Any broker-dealer that holds Old Notes acquired for its own account as a result of market-making activities or other trading activities and receives New Notes for its own account pursuant to the exchange offer and resells such New Notes and any broker-dealer that participates in a distribution of such New Notes may be a statutory “underwriter” within the meaning of the Securities Act, and any profit on any such resale of New Notes and any commission or concessions received by any such persons may be deemed to be underwriting compensation under the Securities Act. The letter of transmittal states that, by acknowledging that it will deliver and by delivering a prospectus meeting the requirements of the Securities Act in connection with the resale of any such New Notes, a broker-dealer will not be deemed to admit that it is an “underwriter” within the meaning of the Securities Act.

commercial banking solutions to small andbusinesses and professionals with operations in our markets. Our market expertise, coupled with a deep understanding of our customers’ needs, allows us to deliver tailored financial products and services. We currently operate eleven branches in the Greater Houston, Dallas-Fort Worth, andAntonio markets, and one branch in Detroit, Texas. We have experienced significant organic growth since commencing banking operations in 2008 as well as growth through our merger with Heritage Bancorp, Inc. (“Heritage”).

The Company also participated in the Main Street Lending Program (the “MSLP”), created by the Board of Governors of the Federal Reserve System (the “Federal Reserve”) to support lending to small andbusinesses and nonprofit organizations that were in sound financial condition before the onset of thepandemic. At December 31, 2021, outstanding MSLP loans, excluding the 95% portion sold to the Federal Reserve and net of deferred loan fees of $1.0 million, were $5.4 million and are included in commercial and industrial loans.

We are subject to vigorous competition in all aspects of our business from banks, savings banks, savings and loan associations, finance companies, credit unions and other providers of financial services, such as money market mutual funds, brokerage firms, consumer finance companies, asset-basedlenders, insurance companies and certain otherentities, including retail stores which may maintain their own credit programs and certain governmental organizations which may offer more favorable financing than we can. Many of the banks and other financial institutions with which we compete have significantly greater financial resources, marketing capability and name recognition than us and operate on a local, statewide, regional or nationwide basis.

our peers. As a result of consolidation among Texas metropolitan banks, we believe we are one of the few remaining locally-based banks in our markets that are dedicated to providing personalized service to small andbusinesses with sophisticated banking needs.

The Bank’s credit department is overseen by the Bank’s Chief Credit Officer. The credit department prepares and providescredit administration reporting to the Bank’s board of directors on a monthly and quarterly basis to aid the Bank’s board of directors in monitoring and adjusting the Bank’s loan focus as it grows. In addition, credit analysts provide analytical and underwriting services in support of the loan officers developing their respective loan portfolios. The Bank’s credit analysts support our most senior loan officers as they are further trained to be our future lending officers.

The Bank has developed an internal loan risk rating system which utilizes risk rating worksheets based upon the type of loan and collateral. Currently, the Bank has risk rating worksheets for commercial and industrial loans, individual loans,occupied real estate loans, owner-occupied real estate loans, andfamily construction loans. Risk rating worksheets are completed for substantially all new loan and renewal requests. In addition, an annual loan review form is completed on real estate loans of $1 million or greater, given that these loans tend to have longer terms than loans that are not secured by real estate. The loan officer will prepare the annual loan review form that updates the credit file with new financials, review of the collateral status, and provide any meaningful commentary that documents changes in the borrower’s overall condition. Upon completion of the annual loan review form, the loan officer must present the form to the Chief Credit Officer for final review, appropriate grade change if needed and then approval to place in the credit file for future reference. We believe this process gives the Chief Credit Officer and executive management strong insight into the underlying performance of the Bank’s loan portfolio, allowing for accurate and proper real-time grading of the loan portfolio.

The Basel III Capital Rules require the Bank to comply with four minimum capital standards: (1) a tier 1 capital to total consolidated assets ratio of at least 4.0%; (2) a common equity tier 1, or CET1, capital to risk-weighted assets ratio of at least 4.5%; (3) a tier 1 capital to risk-weighted assets ratio of at least 6.0%; and (4) a total capital to risk-weighted assets ratio of at least 8.0%. CET1 capital is generally comprised of common shareholders’ equity and retained earnings. Tier 1 capital is generally comprised of CET1 capital and “additional tier 1 capital,” which generally includes certain noncumulative perpetual preferred stock and related surplus and minority interests in equity accounts of consolidated subsidiaries. Total capital includes tier 1 capital (CET1 capital plus additional tier 1 capital) and tier 2 capital. Tier 2 capital is generally comprised of capital instruments and related surplus meeting specified requirements, and may include cumulative preferred stock and long-term perpetual preferred stock, mandatory convertible securities, intermediate preferred stock and subordinated debt. Also included in tier 2 capital is the allowance limited to a maximum of 1.25% of risk-weighted assets and, for institutions that have exercised anelection regarding the treatment of Accumulated Other Comprehensive Income, or AOCI, up to 45% of net unrealized gains onequity securities with readily determinable fair market values. Institutions that have not exercised the AOCIhave AOCI incorporated into CET1 capital (including unrealized gains and losses onWe determined toof this requirement. The calculation of all types of regulatory capital is subject to deductions and adjustments specified in the regulations.

The minimum capital ratios under the Basel III Capital Rules as applicable to the Bank after the fullperiod of the capital conservation buffer are summarized in the table below.

In determining the amount of risk-weighted assets for purposes of calculating risk-based capital ratios, a banking organization’s assets, including certainsheet assets (e.g., recourse obligations, direct credit substitutes, residual interests), are multiplied by a risk weight factor assigned by the regulations based on perceived risks inherent in the type of asset. As a result, higher levels of capital are required for asset categories believed to present greater risk. For example, a risk weight of 0% is assigned to cash and U.S. government securities, a risk weight of 50% is generally assigned to prudently underwritten first lienfamily residential mortgages, a risk weight of 100% is assigned to commercial and consumer loans, a risk weight of 150% is assigned to certain past due loans and a risk weight of between 0% to 600% is assigned to permissible equity interests, depending on certain specified factors. The Basel III Capital Rules increased the risk weights for a

As of December 31, 2021, the Bank’s capital ratios exceeded the minimum capital ratio requirements under the Basel III Capital Rules on a fullybasis. At this time, the Company is not required to comply with the Basel III Capital Rules because the Company is subject to the SBHC Policy Statement.

The BHCA generally requires the prior approval by the Federal Reserve for any merger involving a bank holding company or a bank holding company’s acquisition of

The Bank is subject to sections 23A and 23B of the Federal Reserve Act, or the Affiliates Act, and the Federal Reserve’s implementing Regulation W. An affiliate of a bank is any company or entity that controls, is controlled by or is under common control with the bank. Accordingly, transactions between the Company, the Bank and anysubsidiaries will be subject to a number of restrictions. The Affiliates Act imposes restrictions and limitations on the Bank from making extensions of credit to, or the issuance of a guarantee or letter of credit on behalf of, the Company or other affiliates, the purchase of, or investment in, stock or other securities thereof, the taking of such securities as collateral for loans and the purchase of assets of the Company or other affiliates. Such restrictions and limitations prevent the Company or other affiliates from borrowing from the Bank unless the loans are secured by marketable obligations of designated amounts. Furthermore, such secured loans and investments by the Bank to or in the Company or to or in any otheraffiliate are limited, individually, to 10% of the Bank’s capital and surplus, and such transactions are limited in the aggregate to 20% of the Bank’s capital and surplus. All such transactions, as well as contracts entered into between the Bank and affiliates, must be on terms that are no less favorable to the Bank than those that would be available fromthird parties. Federal Reserve policies also forbid the payment by bank subsidiaries of management fees which are unreasonable in amount or exceed the fair market value of the services rendered or, if no market exists, actual costs plus a reasonable profit.

Under the GLBA, subject to certain conditions imposed by their respective banking regulators, national and state-chartered banks are permitted to form “financial subsidiaries” that may conduct financial activities or activities incidental thereto, thereby permitting bank subsidiaries to engage in certain activities that previously were impermissible. The GLBA imposes several safeguards and restrictions on financial subsidiaries, including that the parent bank’s equity investment in the financial subsidiary be deducted from the bank’s assets and tangible equity for purposes of calculating the bank’s capital adequacy. In addition, the GLBA imposed new restrictions on transactions between a bank and its financial subsidiaries similar to restrictions applicable to transactions between banks andaffiliates.

The authority of the Bank to extend credit to its directors, executive officers and principal shareholders, including their immediate family members and corporations and other entities that they control, is subject to substantial restrictions and requirements under the Federal Reserve’s Regulation O, as well as the Sarbanes-Oxley Act. These statutes and regulations impose limits on the amount of loans the Bank may make to directors and other insiders and require that the loans must be made on substantially the same terms, including interest rates and collateral, as prevailing at the time for comparable transactions with persons not affiliated with the Company or the Bank, that the Bank must follow credit underwriting procedures at least as stringent as those applicable to comparable transactions with persons who are not affiliated with the Company or the Bank, and that the loans must not involve a greater than normal risk ofor include other features not favorable to the Bank. Furthermore, the Bank must periodically report all loans made to directors and other insiders to the bank regulators.

The Bank is subject to limits on the amount of loans it can make to one borrower. With certain limited exceptions, loans and extensions of credit from the Bank to any borrower (including certain related entities of the borrower) at any one time may not exceed 25% of the tier 1 capital of the Bank. The Bank may lend an additional amount if the loan is fully secured by certain types of collateral, like bonds or notes of the United States. Certain types of loans are exempted from the lending limits, including loans secured by segregated deposits held by the Bank.

The federal banking agencies have adopted guidelines establishing operational and managerial standards to promote the safety and soundness of federally insured depository institutions. The guidelines set forth standards for internal controls, information systems, internal audit systems, loan documentation, credit underwriting, interest rate exposure, asset growth, compensation, fees and benefits, asset quality and earnings.

Deposit-taking banking offices of the Bank must be approved by the Federal Reserve and the TDSML, which consider a number of factors including financial history, capital adequacy, earnings prospects, character of management, needs of the community and consistency with corporate power. The Dodd-Frank Act permits insured state banks to engage in interstate branching if the laws of the state where the new banking office is to be established would permit the establishment of the banking office if it were chartered by a bank in such state. Finally, the Company may also establish banking offices in other states by merging with banks or by purchasing banking offices of other banks in other states, subject to certain restrictions.