MGE Energy Inc美股招股说明书(2026-02-24版)

Up to $100,000,000 MGE Energy, Inc. Common Stock We have entered into an equity distribution agreement (the “Equity Distribution Agreement”) with Guggenheim Securities,LLC and Morgan Stanley & Co. LLC, as sales agents and/or principals (each, a “Manager” and, collectively, the “Managers”)relating to the offer and sale of shares of our common stock, par value $1 per share, having an aggregate offering price of up to$100,000,000, from time to time, through the Managers, acting as our sales agents, or directly to one or more of the Managers,acting as principals. Sales of shares of our common stock, if any, as contemplated by this prospectus supplement made through the Managersmay be made by any method deemed to be an “at the market” offering as defined in Rule 415(a)(4) promulgated under theSecurities Act of 1933, as amended (the “Securities Act”), including by means of ordinary brokers’ transactions on the NasdaqGlobal Select Market (“Nasdaq”) at market prices or otherwise at prices related to prevailing market prices or at negotiated prices,by privately negotiated transactions (including block sales) or by any other methods permitted by applicable law. None of the Managers is required to sell any specific number or dollar amount of shares of our common stock, but eachhas agreed, subject to the terms and conditions of the Equity Distribution Agreement, to use its commercially reasonable efforts,consistent with its normal trading and sales practices and applicable law and regulations, to sell shares of our common stock on theterms agreed upon by such Manager and us from time to time. The Equity Distribution Agreement provides that the shares of ourcommon stock offered and sold through the Managers, as our sales agents, pursuant to the Equity Distribution Agreement will beoffered and sold through only one Manager at any given time. The compensation to each Manager for sales of common stock sold through it as our sales agent pursuant to the EquityDistribution Agreement will be an amount up to 2.0% of the gross offering proceeds of any shares of common stock sold under theEquity Distribution Agreement. In connection with the sale of the common stock on our behalf, each Manager will be deemed to bean “underwriter” within the meaning of the Securities Act and the compensation of each Manager will be deemed to beunderwriting commissions or discounts. See “Plan of Distribution” beginning on page S-11 for additional information regarding thecompensation to be paid to the Managers. We have also agreed to provide indemnification and contribution to the Managers withrespect to certain liabilities, including liabilities under the Securities Act or the Securities Exchange Act of 1934, as amended (the“Exchange Act”). Under the terms of the Equity Distribution Agreement, we may also sell shares of our common stock to one or more of theManagers as principal, at a price per share to be agreed upon at the time of sale. If we sell shares to one or more of the Managers asprincipal, we will enter into a separate written agreement with such Manager or Managers, as the case may be. Our common stock is quoted on the Nasdaq under the symbol “MGEE.” On February 23, 2026, the last reported sale priceof our common stock on Nasdaq was $81.50 per share. Investing in our common stock involves risks. For more information, see“Risk Factors”beginning on page S-3 ofthis prospectus supplement and the “Risk Factors” section in our most recent Annual Report onForm 10-K, as updated byany subsequently filed Quarterly Reports on Form 10-Q, each of which is incorporated by reference into this prospectussupplement. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapprovedof these securities or passed upon the adequacy or accuracy of this prospectus supplement or the accompanying prospectus.Any representation to the contrary is a criminal offense. Guggenheim Securities Morgan Stanley TABLE OF CONTENTS Prospectus Supplement About This Prospectus SupplementForward-Looking StatementsProspectus Supplement SummaryRisk FactorsUse of ProceedsDescription of Common StockDividend PolicyMaterial U.S. Federal Income Tax Consequences to Non-U.S. HoldersPlan of DistributionLegal MattersExpertsWhere You Can Find More Information Prospectus About This ProspectusForward-Looking StatementsMGE Energy, Inc.Risk FactorsUse of ProceedsDescription of Common StockCommon Stock Dividends and MarketDescription of Debt SecuritiesDescription of WarrantsDescription of Stock Purchase Contracts and Stock Purchase UnitsDescription of UnitsPlan of DistributionLegal MattersExpertsWhere You Can Find More Information ABOUT THIS PROSPECTUS SUPPLEMENT This document is in two parts. The first part is the prospectus supplement, which describes the specific terms of thiscommon stock offering and certain other matters relating to us and our financial condition. The second part, the accompanyingprospectus, gives more general