X4 Pharmaceuticals upsized with full option exercise, $145.6M expected

Rhea-AI Filing Summary

X4 Pharmaceuticals announced an underwritten public offering of 45,860,000 shares of common stock at $2.90 per share and, in lieu of shares to certain investors, pre-funded warrants for 700,000 shares at $2.899 per warrant. The underwriters’ 30‑day option to purchase up to 6,984,000 additional shares was exercised in full on October 24, 2025.

The company expects net proceeds of approximately $145.6 million, after underwriting discounts, commissions, and estimated expenses. The securities were offered off an effective shelf registration, with a final prospectus supplement filed October 24, 2025. Closing is expected on October 27, 2025, subject to standard conditions. The pre-funded warrants are exercisable at any time, subject to beneficial ownership limits of 4.99% or 9.99%, adjustable up to 19.99% with 61 days’ prior notice.

Insights

Equity Capital Markets Analyst

Primary equity raise delivers $145.6M in net proceeds via underwritten deal.

X4 Pharmaceuticals priced a common stock and pre-funded warrant offering, with underwriters fully exercising the 6,984,000-share option. The transaction uses an effective shelf and a filed final prospectus supplement, indicating standard market execution.

Pre-funded warrants carry an exercise price of $0.001 per share and include Beneficial Ownership Limitations of 4.99% or 9.99%, adjustable up to 19.99% with 61 days’ notice. These caps can pace conversions into common stock, depending on holder decisions.

Key figures to track from the disclosure are the aggregate shares sold at $2.90, the 700,000 pre-funded warrants at $2.899, and expected net proceeds of $145.6M. Closing is anticipated on October 27, 2025, subject to standard conditions.

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): October 23, 2025

X4 PHARMACEUTICALS, INC.

(Exact name of registrant as specified in its charter)

Delaware

001-38295

27-3181608

(State or other jurisdiction of incorporation)

(Commission File Number)

(IRS Employer Identification No.)

61 North Beacon Street,			4th Floor
Boston,			Massachusetts						02134
(Address of principal executive offices)									(Zip Code)

Registrant’s telephone number, including area code is (857) 529-8300

Not applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐    Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐    Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐    Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐    Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class

Trading Symbol(s)

Name of each exchange on which registered

Common Stock, par value $0.001 per share

XFOR

The Nasdaq Stock Market LLC

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

Item 1.01 Entry into a Material Definitive Agreement.

On October 23, 2025, X4 Pharmaceuticals, Inc. (the “Company”) entered into an underwriting agreement (“Underwriting Agreement”) with Leerink Partners LLC, Stifel, Nicolaus & Company, Incorporated and Guggenheim Securities, LLC, as the representatives of the underwriters named therein (the “Underwriters”), to issue and sell 45,860,000 shares of the Company’s common stock at a public offering price of $2.90 per share and, in lieu of common stock to certain investors, pre-funded warrants to purchase 700,000 shares of the Company’s common stock (the “Pre-Funded Warrants”) at a public offering price of $2.899 per share, which represents the per share public offering price for the common stock less the $0.001 per share exercise price for each Pre-Funded Warrant (the “Offering”). In addition, the Company has granted the Underwriters an option for a period of 30 days to purchase up to an additional 6,984,000 shares of its common stock at the public offering price, less the underwriting discounts and commissions, which the Underwriters exercised in full on October 24, 2025.

The Pre-Funded Warrants will be exercisable at any time after the date of issuance. A holder of Pre-Funded Warrants may not exercise the warrant if the holder, together with its affiliates, would beneficially own more than 4.99% or 9.99%, as applicable, of the number of shares of common stock outstanding immediately after giving effect to such exercise. A holder of Pre-Funded Warrants may increase or decrease this percentage to a percentage not in excess of 19.99% by providing prior notice to the Company, provided that any increase will not be effective until the 61st day after such notice is delivered to the Company.

The net proceeds from the Offering are expected to be approximately $145.6 million, after deducting the Underwriters’ discounts and commissions and estimated offering expenses.

The securities described above were offered pursuant to a shelf registration statement (File No. 333-273961), which was declared effective on August 24, 2023. A final prospectus supplement dated October 23, 2025 relating to and describing the terms of the Offering was filed with the U.S. Securities and Exchange Commission on October 24, 2025. The Offering is expected to close subject to satisfaction of standard closing conditions on October 27, 2025.

In the Underwriting Agreement, the Company agreed to indemnify the Underwriters against certain liabilities, including liabilities under the Securities Act of 1933, as amended, or to contribute payments that the underwriters may be required to make because of such liabilities.

Copies of the Underwriting Agreement and the form of Pre-Funded Warrant are filed as Exhibit 1.1 and 4.1, respectively, and are incorporated herein by reference. The foregoing descriptions of the Underwriting Agreement and the Pre-Funded Warrants do not purport to be complete and are qualified in their entirety by reference to such exhibits.

A copy of the opinion of Gibson, Dunn & Crutcher LLP relating to the validity of the issuance and sale of the shares of common stock and the Pre-Funded Warrants in the Offering is filed herewith as Exhibit 5.1.

Item 9.01						Financial Statements and Exhibits.
(d) Exhibits.
EXHIBIT INDEX
Exhibit No.						Description
1.1						Underwriting Agreement, dated as of October 23, 2025, by and among X4 Pharmaceuticals, Inc., Leerink Partners LLC, Stifel, Nicolaus & Company, Incorporated and Guggenheim Securities, LLC.
4.1						Form of Pre-Funded Warrant.
5.1						Opinion of Gibson, Dunn & Crutcher LLP.
23.1						Consent of Gibson, Dunn & Crutcher LLP (included in Exhibit 5.1).
104						Cover Page Interactive Data File (embedded within the Inline XBRL document).

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934 the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

X4 PHARMACEUTICALS, INC.

Date: October 24, 2025

By:

/s/ David H. Kirske

Name:

David H. Kirske

Title:

Chief Financial Officer

FAQ

What did XFOR announce in its 8-K?

X4 Pharmaceuticals priced an underwritten public offering of 45,860,000 common shares at $2.90 and pre-funded warrants for 700,000 shares at $2.899.

How much does XFOR expect to raise from the offering?

The company expects net proceeds of approximately $145.6 million after discounts, commissions, and estimated expenses.

Did the underwriters exercise their option?

Yes. The 30-day option to purchase up to 6,984,000 additional shares was exercised in full on October 24, 2025.

When is the offering expected to close?

Closing is expected on October 27, 2025, subject to satisfaction of standard closing conditions.

What are the pre-funded warrant terms?

They are exercisable at any time with an exercise price of $0.001 per share and include beneficial ownership limits of 4.99% or 9.99%, adjustable up to 19.99% with 61 days’ notice.

Under what registration was the offering made?

The securities were offered under shelf registration statement File No. 333-273961, declared effective on August 24, 2023.