As Filed Pursuant to Rule 424(b)(3)
Registration No. 333-261871
PROSPECTUS
2,008,032 Shares
Common Stock Offered by the Selling Stockholder
This prospectus relates to the resale from time to time of up to 2,008,032 shares of common stock, par value $0.001 per share, of X4
Pharmaceuticals, Inc. (the Common Stock) by the selling stockholder listed on page 7 (the Selling Stockholder), including its pledgees, assignees, donees, transferees or their respective successors-in-interest, which consists of 2,008,032 shares of our Common Stock issuable upon the exercise of outstanding pre-funded warrants to purchase shares of our
Common Stock held by the Selling Stockholder. We will not receive any proceeds from the sale of the shares offered by this prospectus.
We
have agreed, pursuant to a registration rights agreement that we have entered into with the Selling Stockholder, to bear all of the expenses incurred in connection with the registration of these shares. The Selling Stockholder will pay or assume
discounts, commissions, fees of underwriters, selling brokers or dealer managers and similar expenses, if any, incurred for the sale of these shares of our Common Stock.
The Selling Stockholder identified in this prospectus, or its pledgees, assignees, donees, transferees or their respective successors-in-interest, may offer the shares from time to time on terms to be determined at the time of sale through ordinary brokerage transactions or through any other means
described in this prospectus under the caption Plan of Distribution. The shares may be sold at fixed prices, at prevailing market prices, at prices related to prevailing market prices or at negotiated prices. For more information on the
Selling Stockholder, see the section entitled Selling Stockholder on page 7.
We may amend or supplement this prospectus from
time to time by filing amendments or supplements as required. You should read the entire prospectus and any amendments or supplements carefully before you make your investment decision.
Our Common Stock is traded on the Nasdaq Capital Market under the symbol XFOR. On December 31, 2021, the last reported sale
price of our Common Stock was $2.29 per share. You are urged to obtain current market quotations for our Common Stock.
We are an emerging growth
company under applicable Securities and Exchange Commission rules and, as such, have elected to comply with certain reduced public company disclosure requirements for this prospectus and future filings. See Prospectus
SummaryImplications of Being an Emerging Growth Company.
Investing
in our Common Stock involves a high degree of risk. You should carefully read and consider the section entitled Risk Factors on page 5 and the risk factors included in our periodic reports filed with the
Securities and Exchange Commission (SEC), in any applicable prospectus supplement and in any other documents we file with the SEC.
NEITHER THE
SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR DETERMINED IF THIS PROSPECTUS IS TRUTHFUL OR COMPLETE. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.
The date of this prospectus is January 3, 2022.