X4 Pharmaceuticals Inc

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐

Check the appropriate box:

X4 Pharmaceuticals, Inc.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement if Other Than the Registrant)

Payment of filing Fee (Check the appropriate box):

X4 PHARMACEUTICALS, INC.

61 North Beacon Street, 4 th Floor

Boston, Massachusetts 02134

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

To Be Held On June 9, 2025

Dear Stockholder of X4 Pharmaceuticals, Inc.:

You are cordially invited to attend the 2025 Annual Meeting of Stockholders of X4 Pharmaceuticals, Inc., a Delaware corporation (the “Company”). The Annual Meeting will be held on Monday, June 9, 2025 at 12:00 p.m. Eastern Time at the offices of Goodwin Procter LLP, 100 Northern Avenue, 17th Floor, Boston, Massachusetts 02210. The Annual Meeting will be held for the following purposes:

1. To elect the one (1) nominee named in the accompanying proxy statement (the “Proxy Statement”), R. Keith Woods, to the Board of Directors to hold office until the 2028 Annual Meeting of Stockholders and until his successor is duly elected and qualified until his earlier death, resignation or removal.

2. To ratify the selection by the Audit Committee of the Board of Directors of PricewaterhouseCoopers LLP as the independent registered public accounting firm of the Company for its fiscal year ending December 31, 2025.

3. To hold a non-binding advisory “say-on-pay” vote on our named executive officer compensation.

4. To conduct any other business properly brought before the Annual Meeting.

These items of business are more fully described in the Proxy Statement accompanying this Notice.

The record date for the Annual Meeting is April 15, 2025. Only stockholders of record at the close of business on that date may vote at the Annual Meeting or any adjournment or postponement thereof. A list of stockholders entitled to vote at the Annual Meeting will be available at our principal executive offices for examination during normal business hours by any stockholder for any purpose germane to the Annual Meeting for a period of ten days ending the day prior to the Annual Meeting. As previously announced, we will be implementing a reverse stock split of our common stock at a reverse stock split ratio of one-for-thirty. Our common stock will begin trading on a split-adjusted basis on Nasdaq at the opening of trading on April 28, 2025.

By Order of the Board of Directors,

Adam Mostafa

Chief Financial Officer, Treasurer and Corporate Secretary

Boston, Massachusetts

You are cordially invited to attend the Annual Meeting. Whether or not you expect to attend the Annual Meeting, please vote by telephone or through the Internet, or, if you receive a paper proxy card by mail, by completing and returning the proxy card mailed to you, as promptly as possible in order to ensure your representation at the Annual Meeting. Voting instructions are provided in the Notice of Internet Availability of Proxy Materials, or, if you receive a paper proxy card by mail, the instructions are printed on your proxy card and included in the accompanying Proxy Statement. Even if you have voted by proxy, you may still vote in person if you attend the Annual Meeting. Please note, however, that if your shares are held of record by a brokerage firm, bank or other agent and you wish to vote at the Annual Meeting, you must obtain a proxy issued in your name from that agent in order to vote your shares that are held in such agent’s name and account.

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