Mayville Engineering Co Inc 美股招股说明书（2026年5月20日版）

4,348,000 Shares Common Stock We are offering 4,348,000 shares of our common stock, no par value per share, as described inthis prospectus supplement and the accompanying prospectus to institutional investors. Our common stock is listed on The New York Stock Exchange under the symbol “MEC.” The lastreported sale price of our common stock on The New York Stock Exchange on May 18, 2026 was $24.92 Investing in our common stock involves a high degree of risk. Please read the “RiskFactors” beginning on page S-4 of this prospectus supplement, as well as in the accompanying Neither the Securities and Exchange Commission nor any state securities commission hasapproved or disapproved of these securities or passed upon the accuracy or adequacy of this Delivery of the shares of common stock to investors is expected to be made on or about May 21,2026, subject to customary closing conditions. Craig-Hallum William Blair TABLE OF CONTENTSProspectus SupplementABOUT THIS PROSPECTUS SUPPLEMENTS-iFORWARD-LOOKING STATEMENTSS-iiPROSPECTUS SUPPLEMENT SUMMARYS-1THE OFFERINGS-3RISK FACTORSS-4USE OF PROCEEDSS-5MATERIAL UNITED STATES FEDERAL INCOME TAX CONSEQUENCES FOR NON-U.S.HOLDERS OF COMMON STOCKS-6UNDERWRITINGS-11LEGAL MATTERSS-18EXPERTSS-18WHERE YOU CAN FIND MORE INFORMATIONS-19INCORPORATION OF CERTAIN INFORMATION BY REFERENCES-19ProspectusABOUT THIS PROSPECTUS1CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS1RISK FACTORS3MAYVILLE ENGINEERING COMPANY, INC.3USE OF PROCEEDS3DESCRIPTION OF CAPITAL STOCK3DESCRIPTION OF THE DEBT SECURITIES9DESCRIPTION OF WARRANTS18DESCRIPTION OF THE PURCHASE CONTRACTS AND PURCHASE UNITS19DESCRIPTION OF UNITS19WHERE YOU CAN FIND MORE INFORMATION20PLAN OF DISTRIBUTION21LEGAL MATTERS23EXPERTS23 Table of Contents ABOUT THIS PROSPECTUS SUPPLEMENT This document is in two parts. The first part is this prospectus supplement, which describes theterms of this offering and also adds to and updates information contained in the accompanying prospectusand the documents incorporated by reference herein or therein. The second part, the accompanyingprospectus, including the documents incorporated by reference into the accompanying prospectus,provides more general information. Generally, when we refer to this prospectus, we are referring to bothparts of this document combined. To the extent there is a conflict between the information contained in this We have not, and the underwriters have not, authorized anyone to provide you with informationdifferent from, or in addition to, that contained or incorporated by reference in this prospectus supplement,the accompanying prospectus or any free writing prospectus prepared by or on behalf of us or to which wemay have referred you in connection with this offering. We and the underwriters take no responsibility for,and can provide no assurance as to the reliability of, any other information that others may give you. The This prospectus supplement does not contain all of the information that is important to you.You should also read and consider the information in the documents to which we have referred you We are offering to sell, and seeking offers to buy, and the underwriters are soliciting offers to buy,these securities only in jurisdictions where offers and sales are permitted. The distribution of thisprospectus supplement and the accompanying prospectus and the offering of the securities in certainjurisdictions may be restricted by law. For investors outside of the United States: neither we nor theunderwriters have done anything that would permit this offering or possession or distribution of thisprospectus supplement and accompanying prospectus in any jurisdiction where action for that purpose isrequired, other than in the United States. You are required to inform yourselves about and to observe any Unless the context otherwise indicates, references in this prospectus supplement to “we,” “our,”“us,” the “Company,” and “MEC” refer, collectively, to Mayville Engineering Company, Inc., a Wisconsin Table of Contents FORWARD-LOOKING STATEMENTS This prospectus supplement, the accompanying prospectus and the documents incorporated byreference herein and therein, contain forward-looking statements within the meaning of the PrivateSecurities Litigation Reform Act of 1995, Section 27A of the Securities Act of 1993 and Section 21E of All statements, other than statements of historical fact, included or incorporated by reference inthis prospectus supplement, the accompanying prospectus and the documents incorporated by referenceherein, including, without limitation, estimates, projections, outlook, guidance, statements relating to ourbusiness plans, strategy, objectives, expected operating results and future financial position, and theassumptions upon which those statements are based, are forward-looking statements. These forward-looking statements generally are identified by the words “believe,” “project,” “expect,” “anticipate,”“estimate,” “forecast,”