AMERICAN SUPERCONDUCTOR CORP DE

Why you received this proxy statement. You are viewing or have received these proxy materials because AMSC’s Board is soliciting your proxy to vote your shares at the Annual Meeting. This proxy statement includes information that we are required to provide to you under the rules of the SEC and that is designed to assist you in voting your shares.

Notice of Internet Availability of Proxy Materials. As permitted by SEC rules, AMSC is making this proxy statement and its 2024 Annual Report available to certain of its stockholders electronically via the Internet. On or about June 13, 2025, we mailed to these stockholders a Notice of Internet Availability of Proxy Materials, or Internet Notice, containing instructions on how to access this proxy statement and our 2024 Annual Report and vote online. If you received an Internet Notice by mail, you will not receive a printed copy of the proxy materials in the mail unless you specifically request them. Instead, the Internet Notice instructs you on how to access and review all of the important information contained in the proxy statement and 2024 Annual Report. The Internet Notice also instructs you on how you may submit your proxy over the Internet. If you received an Internet Notice by mail and would like to receive a printed copy of our proxy materials, then you should follow the instructions for requesting such materials contained on the Internet Notice.

Printed Copies of Our Proxy Materials. Some of our stockholders received printed copies of our proxy statement, 2024 Annual Report and proxy card. If you received printed copies of our proxy materials, then instructions regarding how you can vote are contained on the proxy card included in the materials.

INFORMATION ABOUT THE ANNUAL MEETING AND VOTING

What is the purpose of the Annual Meeting?

At our Annual Meeting, stockholders will act upon the matters outlined in the accompanying notice of meeting, including the election of the directors named in this proxy statement, the ratification of the appointment of our independent registered public accounting firm and the approval, on an advisory basis, of the compensation of our named executive officers. Stockholders may also consider such other business as may properly come before the meeting. We are not aware of any other business to be brought before the meeting. If any other business is properly brought before the meeting, the designated officers serving as proxies will vote in accordance with their best judgment.

Who is entitled to vote?

You are entitled to vote at the Annual Meeting, or any continuation, postponement or adjournment of the Annual Meeting, only if you were a stockholder of record at the close of business on the record date, May 29, 2025, or if you hold a valid proxy for the Annual Meeting. The number of stockholders of record as of the May 29, 2025 record date was 179. Holders of shares of our common stock are entitled to one vote per share.

Why is AMSC hosting the Annual Meeting in a virtual meeting format only?

A virtual meeting enables increased stockholder attendance and participation because stockholders can participate from any location around the world. The virtual Annual Meeting has been designed to provide the same rights to participate as you would have at anin-person meeting. Because our Annual Meeting is being held virtually over the internet, when we refer to “in person” for aspects pertaining to the Annual Meeting, we mean live virtual attendance through the means described in this proxy statement.

How do I attend the virtual Annual Meeting?

Stockholders of record as of May 29, 2025 will be able to attend and participate in the Annual Meeting online by accessing www.virtualshareholdermeeting.com/AMSC2025. To join the Annual Meeting, you will need to have your 16-digit control number which is included on your Internet Notice, your proxy card (if you received a printed copy of the proxy materials) or the instructions that accompanied the proxy materials.

Even if you plan to attend the Annual Meeting online, we recommend that you also vote by proxy as described herein so that your vote will be counted if you subsequently decide not to attend the Annual Meeting.

Access to the Audio Webcast of the Annual Meeting. The live audio webcast of the Annual Meeting will begin promptly at 10:30 a.m. Eastern Time on July 25, 2025. We encourage our stockholders to access the meeting website prior to the start time. Online access to the audio webcast will open approximately 15 minutes prior to the start of the Annual Meeting to allow time for you to log in and test the computer audio system.

Log in Procedures. To attend the virtual Annual Meeting, visit www.virtualshareholdermeeting.com/AMSC2025 to log in. Stockholders will need their unique 16-digit control number included in your Internet Notice (printed in the box and marked by the arrow), proxy card or the instructions that accompanied the proxy materials. If your shares are held in “street name” (through a bank, broker or other nominee), you should contact your bank, broker or other nominee as soon as possible to obtain your 16-digit control number or otherwise vote through the bank, broker or other nominee.

If you lose your 16-digit control number, you may join the Annual Meeting as a “Guest” but you will not be able to vote, ask questions or access the list of stockholders as of the record date.

Technical Assistance. Beginning 15 minutes prior to the start of and during the virtual Annual Meeting, we will have technicians ready to assist stockholders with any technical difficulties they may have accessing or hearing the virtual meeting. If you encounter any difficulties accessing the virtual meeting during thecheck-in or meeting time, please call the technical support number that will be posted on the annual meeting websitelog-in page.

Will there be a question and answer session during the Annual Meeting?

As part of the Annual Meeting, we will hold a live questions and answers session, during which we intend to answer questions submitted online during the meeting that are pertinent to AMSC and the meeting matters, for up to fifteen minutes following the completion of the Annual Meeting. Only stockholders that have accessed the Annual Meeting as a stockholder (rather than a “Guest”) by following the procedures outlined above in “How do I attend the virtual Annual Meeting?” will be permitted to submit questions during the Annual Meeting. Each stockholder is limited to two questions, each up to a maximum of 1000 characters, in order to allow us to answer questions from as many stockholders as possible. Questions should be succinct and only cover a single topic. We will not address questions that are, among other things:

Questions and answers may be grouped by topic, and we may group substantially similar questions together and answer them once. If there are matters of individual concern to a stockholder and not of general concern to all stockholders, or if a question posed was not otherwise answered, we encourage stockholders to contact us separately after the Annual Meeting.

Additional information regarding the question and answer session will be available in the “Rules of Conduct” available on the Annual Meeting webpage for stockholders that have accessed the Annual Meeting as a stockholder (rather than a “Guest”) by following the procedures outlined above in “How do I attend the virtual Annual Meeting?”.

What constitutes a quorum?

The holders of a majority of the shares of common stock outstanding and entitled to vote at the Annual Meeting will constitute a quorum for the transaction of business at the Annual Meeting. Shares of common stock represented in person or by proxy (including shares that abstain or do not vote with respect to one or more of the matters presented for stockholder approval) will be counted as present and entitled to vote for purposes of determining whether a quorum is present at the Annual Meeting. As of the May 29, 2025 record date, 40,382,666 shares of our common stock were outstanding and entitled to vote.

How do I vote?

If you are a stockholder of record, meaning your shares are registered in your name, you may vote:

(1)Over the Internet: Go to the website of our tabulator, Broadridge, atwww.proxyvote.com. Use the 16-digit control number printed on your Internet Notice, proxy card or the instructions that accompanied the proxy materials to access your account and vote your shares. You must specify how you want your shares voted or your Internet vote cannot be completed and you will receive an error message. Your shares will be voted according to your instructions.

(2)By Telephone: Call 1-800-690-6903, toll free from the U.S. and Canada, and follow the instructions on your proxy card. You must specify how you want your shares voted and confirm your vote at the end of the call or your telephone vote cannot be completed. Your shares will be voted according to your instructions.

(3)By Mail: Complete and sign your proxy card and mail it in the accompanying postage prepaid envelope to Broadridge, 51 Mercedes Way, Edgewood, NY 11717. Your shares will be voted according to your instructions. If you do not specify how you want your shares voted, they will be voted as recommended by our Board of Directors.

(4)In Person during the Virtual Annual Meeting: You may attend the virtual Annual Meeting and vote during the meeting even if you have already voted by proxy. To vote during the meeting, visitwww.virtualshareholdermeeting.com/AMSC2025 on the day of the meeting; you will need the 16-digit control number provided on your Internet Notice or proxy card.

If your shares are held in “street name,” meaning they are held for your account by a bank, broker or other nominee, you may vote:

(1)Over the Internet or by Telephone: You will receive instructions from your bank, broker or other nominee if they permit Internet or telephone voting. You should follow those instructions.

(2)By Mail: You will receive instructions from your bank, broker or other nominee explaining how you can vote your shares by mail. You should follow those instructions.

(3)In Person during the Virtual Annual Meeting: If your shares are not registered in your own name and you would like to vote your shares electronically at the Annual Meeting, you should contact your bank or broker to obtain your 16-digit control number or instructions on how to vote at the meeting through the bank or broker.

Can I change my proxy after I return my proxy card?

Yes. You may revoke your proxy and change your vote at any time before the Annual Meeting. To do so, you must do one of the following:

(1) Vote over the Internet or by telephone as instructed above. Only your latest Internet or telephone vote is counted.

(2) Sign a new proxy card and submit it as instructed above. Only your latest dated proxy card will be counted.

(3) Attend the Annual Meeting, request that your proxy be revoked and vote in person as instructed above. Attending the Annual Meeting will not revoke your proxy unless you specifically request it.

Will my shares be voted if I don’t return my proxy?

If your shares are registered directly in your name, your shares will not be voted if you do not vote over the Internet, by telephone, by returning your proxy card or voting at the Annual Meeting. If your shares are held in “street name” by a bank, broker or other nominee, that person, as the record holder of your shares, is required to vote your shares according to your instructions. Your bank, broker or other nominee will send you directions on how to vote those shares. Under applicable stock exchange rules, if you do not give instructions to your bank, broker or other nominee, it will still be able to vote your shares with respect to certain “discretionary” items, such as the ratification of the appointment of RSM US LLP (“RSM”) as our independent registered public accounting firm, but will not be allowed to vote your shares with respect to certain“non-discretionary” items, such as the election of directors, and the approval, on an advisory basis, of the compensation of our named executive officers. In the case of“non-discretionary” items, shares for which your bank, broker or other nominee does not receive voting instructions will be treated as “brokernon-votes.”

What is the vote required to approve each matter?

(1)Election of Directors. Directors will be elected by a plurality of the votes cast by the stockholders entitled to vote on the election. This means that the seven nominees receiving the most affirmative votes will be elected as directors at the Annual Meeting. Votes withheld and “brokernon-votes” will have no effect on the outcome of the election of directors.

(2)Ratification of the Appointment of our Independent Registered Public Accounting Firm. The affirmative vote of the holders of the shares of common stock having a majority of the votes cast by the holders of all of the shares of common stock present or represented and voting on the matter is required for the ratification of the appointment by the Audit Committee of RSM as our independent registered public accounting firm for the current fiscal year. Abstentions and “brokernon-votes” will have no effect on the outcome of this proposal. Because brokers have discretionary authority to vote on the ratification of the appointment of our independent registered public accounting firm, we do not expect any “brokernon-votes” in connection with this proposal.

(3)Approval, on an Advisory Basis, of Named Executive Officer Compensation. The affirmative vote of the holders of the shares of common stock having a majority of the votes cast by the holders of all of the shares of common stock present or represented and voting on the matter is required for the approval, on an advisory basis, of the compensation of our named executive officers. Abstentions and “brokernon-votes” will have no effect on the outcome of the proposal. This proposal isnon-binding.

Who will count the votes?

Our Board of Directors has appointed a representative of Broadridge Financial Solutions to serve as the inspector of elections at the Annual Meeting and to tabulate the votes.

Are there other matters to be voted on at the meeting?

As of the date of this proxy statement, our Board of Directors does not know of any other matters which may come before the meeting, other than the matters described in this proxy statement. Should any other matter requiring a vote of our stockholders arise and be properly presented at the Annual Meeting, the proxy for the Annual Meeting confers upon the persons named in the proxy and designated to vote the shares discretionary authority to vote, or otherwise act, with respect to any such matter in accordance with their best judgment.

Our Board encourages stockholders to attend the virtual Annual Meeting. Whether or not you plan to attend, you are urged to submit your proxy. Prompt response will greatly facilitate arrangements for the meeting and your cooperation will be appreciated. Stockholders who attend the virtual Annual Meeting may vote their stock personally even though they may have sent in their proxies.

STOCK OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

The following table sets forth the beneficial ownership of our common stock as of May 29, 2025, or such earlier date as indicated below, by:

Unless otherwise provided, the address of each individual listed below is c/o American Superconductor Corporation, 114 East Main Street, Ayer, Massachusetts 01432.