MGE ENERGY INC

UNITED STATESSECURITIES AND EXCHANGE COMMISSIONWashington, D.C. 20549

SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of theSecurities Exchange Act of 1934

Filed by registrant: ☒ Filed by a Party other than the Registrant: ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☒ Definitive Proxy Statement ☐ Definitive Additional Materials ☐ Soliciting Material under §240.14a-12 MGE Energy, Inc.(Name of Registrant as Specified In Its Charter) (Name of Person(s) Filing Proxy Statement, if other than the Registrant) Check the appropriate box: ☒ No Fee Required ☐ Fee paid previously with preliminary materials ☐ Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a6(i)(1) and 0-11

About MGE Energy MGE Energy, Inc. (MGE Energy or the Company), is an investor-owned public utility holding company headquartered in the state capital of Madison, Wis. MGE Energy is the parent company of Madison Gas and Electric Company (MGE), your community energy company. With roots in the community dating back more than 150 years, the utility provides affordable natural gas and electric service in south-central and western Wisconsin.

From Our Chairman, President and CEO

Dear Fellow Shareholders: Please join us online at this year’s MGE Energy Annual Meeting of Shareholders beginning at 11 a.m., Central Time, on Tuesday, May 20, 2025. In addition to formal business of the meeting, the annual meeting is an opportunity to share the past year’s performance, our progress toward our goals and our vision for the future of your Company. Please review the attached Proxy Statement and cast your vote. MGE Energy continues to succeed. In 2024, we continued to grow our use of carbon-free renewable energy generation, delivered customer value through innovative programs and invested in our systems to serve our customers safely andreliably into the future. Within the last year, we continued our energy supply transition to enable deep decarbonization. Those generation investments included:

Jeff Keebler

Chairman, President and CEO

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Darien Solar. MGE is a co-owner of this 250-megawatt (MW) solar project in Rock and Walworth counties. MGE owns 25 MW of solar capacity. MGE will own 7.5 MW of the project's battery storage, which is expected online in 2026.

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MGE’s Strix Solar array. The 6-MW array came online in early 2025 to serve all customers and customers who enroll in our proposed community solar program, if it’s approved. The Shared Solar-Strix program builds on the success of MGE’s existing Shared Solar program to provide affordable, local solar energy.

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Paris Solar. MGE is a co-owner of this 200-MW solar project in Kenosha County. The 110-MW battery is expected online this year. MGE owns 20 MW of solar capacity and will own 11 MW of the battery storage.

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Tyto Solar. Like Strix Solar, this 6-MW facility is a distributed energy resource directly connected to MGE’s distribution grid to deliver cost-effective local solar to our electric customers.

We also introduced and began to enroll customers in MGE’s renewable natural gas (RNG) option. This program offering is similar to MGE’s Green Power Tomorrow (GPT) program for electric customers. GPT RNG, as the program is known, offers customers an easy way to offset their emissions from their use of natural gas. MGE is the first utility in Wisconsin to offer this type of program for natural gas customers who wish to offset their natural gas emissions.

MGE also continues to innovate in how we work to advance the growth of electric vehicles (EVs) and EV charging. Transportation is the largest source of direct greenhouse gas emissions in the U.S.

In 2024, we filed for regulatory approval for a program to help business customers who want to install EV charging to manage the up-front costs of the chargers. We also continued to expand our network of publicly available fast-charging stations.

Regular engagement with our customers helps to inform our programs, products and services to better serve them, our communities, and you, our shareholders. As your community energy company, engagement is one of our core values. It is part of how we fulfill our obligation and part of how we will achieve our goals.

Electrification and energy efficiency—two key decarbonization strategies—become more powerful as we decarbonize our grid. We’ll continue to work with our customers to advance these strategies in pursuit of our shared goals for a more sustainable future.

MGE Energy also continues to deliver consistent financial performance with another year of strong earnings. We also continue to maintain top credit ratings, helping to enable our ongoing generation transformation.

Thank you for choosing MGE Energy for your investment. It is a privilege and honor to serve you and our broader community of customers.

Sincerely,

Jeff M. Keebler

Chairman, President and CEO

April 4, 2025

From Our Lead Independent Director

Dear Fellow Shareholders: On behalf of the Board of Directors, thank you for your investment in MGE Energy and for the trust you place in each of us to serve in this capacity. We encourage you to attend the Company’s 2025 Annual Meeting. It has been my honor to serve as Lead Independent Director since May 2024. As Lead Independent Director, one of my responsibilities is chairing our Corporate Governance Committee, which works to ensure the board is structured to provide for strong and consistent independent oversight as well as transparency and accountability. Since 2018, the board has welcomed six new directors who add talent, broad experience and diverse expertise to our board. Every year, the committee conducts an assessment of the board’s effectiveness as a whole. Our board is active and engaged in overseeing the Company's long-term strategic direction and effectively providing long-term value to both customers and shareholders.

Jim Possin

Lead Independent Director

Executive leadership, senior management and external subject matter experts regularly attend board meetings to address matters of strategic importance, which aid the directors in oversight and decision-making. In late summer 2024, the board held a strategic planning and review session with Company officers.

The board also holds a comprehensive risk assessment twice a year, which complements a broad-based exercise on risk that is conducted by directors with all Company officers every other year. These periodic sessions offer directors the opportunity to engage MGE executives directly on corporate strategy and the long-term risks and opportunities faced by the Company.

Oversight of historic capital investment

MGE Energy and MGE are undergoing a historic transformation in how the utility serves its communities with safe, reliable energy. The board is committed to its fundamental oversight role in ensuring the Company’s long-term strategic direction is executed responsibly and effectively to provide long-term value to both customers and shareholders. More than half of the Company’s projected capital expenditures from 2025 through 2029 will support cost-effective generation investments to achieve MGE’s science-based carbon reduction goals. Through sound governance policies and practices, your board is well equipped to oversee the Company's long-term strategy and to evaluate its performance throughout this ongoing transformation.

This Proxy Statement includes more information about MGE Energy’s financial performance as well as our oversight of the Company. Please review it and vote your shares promptly. We value our shareholders’ perspectives, which help to inform the Company’s policies and practices. Thank you for your attention.

Sincerely,

James L. Possin

Lead Independent Director

April 4, 2025

Notice of 2025 Annual Meeting of Shareholders

Regardless of whether you plan to attend the MGE Energy, Inc., 2025 Annual Meeting of Shareholders (the Annual Meeting), please take a moment to vote your proxy.

The Annual Meeting will be held virtually, using the same format as last year's meeting. As always, we encourage you to vote your shares prior to the meeting date.

Meeting Information The meeting will be held as follows: Date: Tuesday, May 20, 2025Time: 11:00 a.m., Central TimePlace: Online at www.virtualshareholdermeeting.com/MGEE2025

Instructions on attending the virtual shareholder meeting are provided in the Questions and Answers under the "Proxy Summary" section of this Proxy Statement. To participate, you will need the 16-digit control number included on your proxy materials. A recorded version of the Annual Meeting will be available online afterward.

By Order of the Board of Directors,

Cari Anne Renlund

Vice President General Counsel and Secretary

This notice of Annual Meeting, Proxy Statement and accompanying proxy card are first being mailed on or about April 4, 2025, to shareholders of record at the close of business on March 21, 2025, the record date for this meeting.

Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting to be Held on May 20, 2025:

This Proxy Statement and our 2024 Annual Report to Shareholders are available atwww.mgeenergy.com/proxy.

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