Deep Track reports 8.33% stake in X4 Pharmaceuticals

Deep Track Capital and affiliates report beneficial ownership of X4 Pharmaceuticals common stock and related securities as of June 30, 2026.

Rhea-AI Filing Summary

Deep Track Capital and affiliates report beneficial ownership of X4 Pharmaceuticals common stock and related securities as of June 30, 2026. The group collectively reports 8,040,894 shares beneficially owned, representing 8.33% of the common stock, all with shared voting and dispositive power.

This position includes 2,162,137 Pre-Funded Warrants exercisable into common stock, subject to a 9.99% "Maximum Percentage" ownership cap that limits exercises if they would push holdings above that threshold. Ownership percentages are based on 96,481,833 shares, including 94,319,696 shares outstanding as of May 1, 2026 plus the shares issuable upon warrant exercise within the cap.

Key Figures

Total beneficial ownership: 8,040,894 shares Ownership percentage: 8.33% Pre-Funded Warrants held: 2,162,137 warrants +5 more

8 metrics

Total beneficial ownership 8,040,894 shares Shares of X4 Pharmaceuticals beneficially owned by the reporting persons as of June 30, 2026

Ownership percentage 8.33% Percent of X4 Pharmaceuticals common stock beneficially owned by the reporting persons

Pre-Funded Warrants held 2,162,137 warrants Pre-Funded Warrants exercisable into common stock, subject to a 9.99% Maximum Percentage limit

Shares outstanding baseline 94,319,696 shares Common stock outstanding as of May 1, 2026, used in ownership calculations

Total shares for calculation 96,481,833 shares Baseline plus shares issuable upon exercise of Pre-Funded Warrants within the cap

Deep Track Master Fund holdings 6,923,680 shares Beneficial ownership (common and warrants) by Deep Track Biotechnology Master Fund, Ltd., 7.18% of class

Special Opportunities Fund holdings 1,117,214 shares Common shares of X4 Pharmaceuticals beneficially owned by Deep Track Special Opportunities Fund, LP, 1.16% of class

Maximum Percentage cap 9.99% Ownership limit above which X4 will not effect warrant exercises

Key Terms

Pre-Funded Warrants, Maximum Percentage, beneficial owner, Schedule 13G, +1 more

5 terms

Pre-Funded Warrants financial

"The beneficially owned shares include 2,162,137 Pre-Funded Warrants exercisable to common stock"

Pre-funded warrants are financial instruments that give investors the right to purchase a company's stock at a set price, but with most or all of the purchase price paid upfront. They function like a coupon or gift card for stock, allowing investors to buy shares later at a fixed price, which can be beneficial if they want to avoid future price increases. This makes them important for investors seeking flexibility and certainty in their investment plans.

Maximum Percentage financial

"subject to a 9.99% Maximum Percentage exercise limitation"

beneficial owner financial

"Deep Track Biotechnology Master Fund Ltd. is the beneficial owner of 4,761,543 Common Stock"

A beneficial owner is the person who ultimately owns or controls a financial asset or property, even if their name isn't directly on official documents. Think of it like someone who secretly holds the keys to a safe deposit box—others may appear to have access, but the true owner is the one who benefits from what's inside. Identifying beneficial owners helps ensure transparency and prevent illegal activities like money laundering or fraud.

Schedule 13G regulatory

"JOINT FILING STATEMENT PURSUANT TO RULE 13d-1(k) The undersigned acknowledge and agree that the foregoing statement on , is filed"

A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.

shared voting power financial

"Shared Voting Power 8,040,894.00"

Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What ownership stake in XFOR does Deep Track Capital report in this Schedule 13G/A?

Deep Track Capital and related reporting persons disclose beneficial ownership of 8,040,894 shares of X4 Pharmaceuticals, representing 8.33% of the common stock outstanding, all held with shared voting and dispositive power rather than sole control.

How many XFOR shares does Deep Track Biotechnology Master Fund own?

Deep Track Biotechnology Master Fund, Ltd. reports being beneficial owner of 6,923,680 shares of X4 Pharmaceuticals, or 7.18% of the common stock. This consists of 4,761,543 common shares plus 2,162,137 Pre-Funded Warrants subject to an ownership cap.

What is the Maximum Percentage ownership limit disclosed for XFOR warrants?

The filing states that Pre-Funded Warrants are subject to a 9.99% "Maximum Percentage" limitation. X4 will not effect warrant exercises that would cause the holder, together with its affiliates, to beneficially own more than 9.99% of the outstanding common stock.

How many XFOR shares are used to calculate Deep Track’s ownership percentage?

Ownership percentages are calculated using 96,481,833 shares. This figure combines 94,319,696 common shares outstanding as of May 1, 2026, as reported in X4’s Form 10-Q, plus 2,162,137 shares issuable upon warrant exercise within the cap.

What portion of XFOR is held by Deep Track Special Opportunities Fund?

Deep Track Special Opportunities Fund, LP reports beneficial ownership of 1,117,214 common shares of X4 Pharmaceuticals, equal to 1.16% of the company’s common stock, with all voting and dispositive power reported as shared rather than sole.

How many XFOR Pre-Funded Warrants are included in Deep Track’s reported holdings?

The reporting persons collectively include 2,162,137 Pre-Funded Warrants in their beneficial ownership. These warrants are exercisable into common stock but are constrained by the 9.99% Maximum Percentage ownership limitation described in the filing.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 08/14/2026 - 08:35 AM Accepted by SEC EDGAR 08/14/2026 - 08:34 AM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 1)

X4 Pharmaceuticals, Inc.

(Name of Issuer)

Common Stock, par value $0.001 per share

(Title of Class of Securities)

98420X202

(CUSIP Number)

06/30/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 98420X202

1

Names of Reporting Persons

Deep Track Capital, LP

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 8,040,894.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 8,040,894.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

8,040,894.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

8.33 %

12

Type of Reporting Person (See Instructions)

IA, OO

SCHEDULE 13G

CUSIP Number(s): 98420X202

1

Names of Reporting Persons

Deep Track Biotechnology Master Fund, Ltd.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 6,923,680.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 6,923,680.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

6,923,680.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

7.18 %

12

Type of Reporting Person (See Instructions)

CO

SCHEDULE 13G

CUSIP Number(s): 98420X202

1

Names of Reporting Persons

David Kroin

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 8,040,894.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 8,040,894.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

8,040,894.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

8.33 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

CUSIP Number(s): 98420X202

1

Names of Reporting Persons

Deep Track Special Opportunities Fund, LP.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 1,117,214.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,117,214.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,117,214.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

1.16 %

12

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: X4 Pharmaceuticals, Inc.
(b)	Address of issuer's principal executive offices: 61 North Beacon Street, 4th Floor, Boston, Massachusetts 02134
Item 2.
(a)	Name of person filing: (i) Deep Track Capital, LP (ii) Deep Track Biotechnology Master Fund, Ltd. (iii) David Kroin (iv) Deep Track Special Opportunities Fund, LP.
(b)	Address or principal business office or, if none, residence: (i) 200 Greenwich Ave, 3rd Floor, Greenwich, CT 06830 (ii) c/o Walkers Corporate Limited, 190 Elgin Ave, George Town, KY1-9001, Cayman Islands (iv) c/o Deep Track Capital, LP, 200 Greenwich Ave, 3rd Floor, Greenwich, CT 06830 (i) 200 Greenwich Ave, 3rd Floor, Greenwich, CT 06830
(c)	Citizenship: (i) Delaware (ii) Cayman Islands (iii) United States (iv) United States
(d)	Title of class of securities: Common Stock, par value $0.001 per share
(e)	CUSIP No.: 98420X202
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 8,040,894
(b)	Percent of class: 8.33%
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 0
	(ii) Shared power to vote or to direct the vote: 8,040,894
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 8,040,894
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary. Deep Track Capital, LP is the relevant entity for which David Kroin may be considered a control person.
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Deep Track Capital, LP

Signature:	/s/ David Kroin
Name/Title:	David Kroin, Managing Member of the General Partner of the Investment Adviser
Date:	08/14/2026

Deep Track Biotechnology Master Fund, Ltd.

Signature:	/s/ David Kroin
Name/Title:	David Kroin, Director
Date:	08/14/2026

David Kroin

Signature:	/s/ David Kroin
Name/Title:	David Kroin
Date:	08/14/2026

Deep Track Special Opportunities Fund, LP.

Signature:	/s/ David Kroin
Name/Title:	David Kroin, Managing Member of the General Partner of the Investment Adviser of Deep Track Special Opportunities Fund, LP
Date:	08/14/2026

Exhibit Information

Item 4: Information with respect to the Reporting Persons' ownership of the Common Stock as of June 30, 2026, is incorporated by reference to items (5) - (9) and (11) of the cover page of the respective Reporting Person. The amount beneficially owned by each Reporting Person is determined using 96,481,833 shares, calculated using 94,319,696 Common Stock outstanding as of May 1, 2026, according to the 10-Q filed with the SEC on May 6, 2026 and 2,162,137 Common Stock that would be converted to Common Stock by the Reporting Person up to the Maximum Percentage. The beneficially owned shares include 2,162,137 Pre-Funded Warrants exercisable to common stock, subject to a 9.99% Maximum Percentage exercise limitation. The Issuer shall not effect the exercise of any portion of the Pre-Funded Warrants to the extent that after giving effect to such exercise, the holder collectively would beneficially own in excess of 9.99% (the "Maximum Percentage") of the number of Common Stock outstanding immediately after giving effect to such exercise. Deep Track Capital LP and David Kroin may be deemed to be considered beneficial owners of a combined 5,878,757 Common Stock, 2,162,137 Pre-Funded Warrants subject to the Maximum Percentage exercise limitation. Deep Track Biotechnology Master Fund Ltd. is the beneficial owner of 4,761,543 Common Stock, 2,162,137 Pre-Funded Warrants subject to the Maximum Percentage exercise limitation. Deep Track Special Opportunities Fund LP is the beneficial owner of 1,117,214 Common Stock. JOINT FILING STATEMENT PURSUANT TO RULE 13d-1(k) The undersigned acknowledge and agree that the foregoing statement on SCHEDULE 13G, is filed on behalf of each of the undersigned and that all subsequent amendments to this statement on SCHEDULE 13G, shall be filed on behalf of each of the undersigned without the necessity of filing additional joint acquisition statements. The undersigned acknowledge that each shall be responsible for the timely filing of such amendments, and for the completeness and accuracy of the information concerning him or it contained therein, but shall not be responsible for the completeness and accuracy of the information concerning the others, except to the extent that he or it knows or has reason to believe that such information is inaccurate. Dated: August 14, 2026 Deep Track Capital, LP By: /s/ David Kroin David Kroin, Managing Member of the General Partner of the Investment Adviser Deep Track Biotechnology Master Fund, Ltd. By: /s/ David Kroin David Kroin, Director David Kroin By: /s/ David Kroin David Kroin Deep Track Special Opportunities Fund, LP. By: /s/ David Kroin David Kroin, Managing Member of the General Partner of the Investment Adviser of Deep Track Special Opportunities Fund, LP