[SCHEDULE 13G] X4 Pharmaceuticals, Inc SEC Filing

Rhea-AI Filing Summary

Coastlands Capital and affiliated entities filed a Schedule 13G reporting beneficial ownership of 2,491,638 shares of X4 Pharmaceuticals (XFOR) common stock, representing 9.99% of the class. The filing shows shared voting and dispositive power over these shares and no sole power.

The calculation is based on 22,449,689 shares outstanding as of August 13, 2025, as cited from an issuer filing, and includes shares issuable upon exercise of pre-funded warrants, reflecting a 9.99% beneficial ownership limitation. The reporting persons state the securities were acquired and are held in the ordinary course and not for the purpose of changing or influencing control.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

X4 Pharmaceuticals, Inc.

(Name of Issuer)

Common Stock, par value $0.001 per share

(Title of Class of Securities)

98420X202

(CUSIP Number)

10/03/2025

(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)

SCHEDULE 13G

CUSIP No. 98420X202

1

Names of Reporting Persons

Coastlands 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 2,491,638.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,491,638.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,491,638.00

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)

9.99 %

12

Type of Reporting Person (See Instructions)

IA, PN

Comment for Type of Reporting Person: The calculation of the beneficial ownership of the Reporting Persons is based on (i) 22,449,689 shares of Common Stock issued and outstanding as of August 13, 2025, as reported by the Issuer in its Registration Statement on Form S-3 filed with the Securities and Exchange Commission on September 10, 2025, and (ii) 2,491,638 shares of Common Stock issuable upon the exercise of pre-funded warrants held by the Reporting Persons, which reflects the beneficial ownership limitation of 9.99%.

SCHEDULE 13G

CUSIP No. 98420X202

1

Names of Reporting Persons

Coastlands Capital Partners 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 2,491,638.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,491,638.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,491,638.00

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)

9.99 %

12

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person: The calculation of the beneficial ownership of the Reporting Persons is based on (i) 22,449,689 shares of Common Stock issued and outstanding as of August 13, 2025, as reported by the Issuer in its Registration Statement on Form S-3 filed with the Securities and Exchange Commission on September 10, 2025, and (ii) 2,491,638 shares of Common Stock issuable upon the exercise of pre-funded warrants held by the Reporting Persons, which reflects the beneficial ownership limitation of 9.99%.

SCHEDULE 13G

CUSIP No. 98420X202

1

Names of Reporting Persons

Coastlands Capital GP LLC

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 2,491,638.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,491,638.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,491,638.00

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)

9.99 %

12

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person: The calculation of the beneficial ownership of the Reporting Persons is based on (i) 22,449,689 shares of Common Stock issued and outstanding as of August 13, 2025, as reported by the Issuer in its Registration Statement on Form S-3 filed with the Securities and Exchange Commission on September 10, 2025, and (ii) 2,491,638 shares of Common Stock issuable upon the exercise of pre-funded warrants held by the Reporting Persons, which reflects the beneficial ownership limitation of 9.99%.

SCHEDULE 13G

CUSIP No. 98420X202

1

Names of Reporting Persons

Coastlands Capital LLC

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 2,491,638.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,491,638.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,491,638.00

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)

9.99 %

12

Type of Reporting Person (See Instructions)

HC, OO

Comment for Type of Reporting Person: The calculation of the beneficial ownership of the Reporting Persons is based on (i) 22,449,689 shares of Common Stock issued and outstanding as of August 13, 2025, as reported by the Issuer in its Registration Statement on Form S-3 filed with the Securities and Exchange Commission on September 10, 2025, and (ii) 2,491,638 shares of Common Stock issuable upon the exercise of pre-funded warrants held by the Reporting Persons, which reflects the beneficial ownership limitation of 9.99%.

SCHEDULE 13G

CUSIP No. 98420X202

1

Names of Reporting Persons

Matthew D. Perry

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 2,491,638.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,491,638.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,491,638.00

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)

9.99 %

12

Type of Reporting Person (See Instructions)

HC, IN

Comment for Type of Reporting Person: The calculation of the beneficial ownership of the Reporting Persons is based on (i) 22,449,689 shares of Common Stock issued and outstanding as of August 13, 2025, as reported by the Issuer in its Registration Statement on Form S-3 filed with the Securities and Exchange Commission on September 10, 2025, and (ii) 2,491,638 shares of Common Stock issuable upon the exercise of pre-funded warrants held by the Reporting Persons, which reflects the beneficial ownership limitation of 9.99%.

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, MA, 02134
Item 2.
(a)	Name of person filing: Coastlands Capital LP, a Delaware limited partnership ("Coastlands") Coastlands Capital Partners LP, a Delaware limited partnership (the "Partnership") Coastlands Capital GP LLC, a Delaware limited liability company (the "General Partner") Coastlands Capital LLC, a Delaware limited liability company ("Coastlands GP") Matthew D. Perry Coastlands and the General Partner are the investment adviser and general partner, respectively, of the Partnership. Coastlands GP is the general partner of Coastlands. Mr. Perry is the control person of Coastlands, the Partnership, Coastlands GP and the General Partner. The reporting persons are filing this Schedule 13G jointly, but not as members of a group, and each disclaims membership in a group. Each reporting person also disclaims beneficial ownership of Common Stock except to the extent of that person's pecuniary interest therein. In addition, the filing of this Schedule 13G on behalf of the Partnership should not be construed as an admission that it is, and it disclaims that it is, a beneficial owner, as defined in Rule 13d-3 under the Act, of any Common Stock covered by this Schedule 13G.
(b)	Address or principal business office or, if none, residence: 601 California Street, Suite 1210, San Francisco, CA 94108
(c)	Citizenship: See Item 4 of the cover sheet for each reporting person.
(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: Coastlands: 2,491,638 Partnership: 2,491,638 General Partner: 2,491,638 Coastlands GP: 2,491,638 Matthew D. Perry: 2,491,638
(b)	Percent of class: Coastlands: 9.99% Partnership: 9.99% General Partner: 9.99% Coastlands GP: 9.99% Matthew D. Perry: 9.99%
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: Coastlands: 0 Partnership: 0 General Partner: 0 Coastlands GP: 0 Matthew D. Perry: 0
	(ii) Shared power to vote or to direct the vote: Coastlands: 2,491,638 Partnership: 2,491,638 General Partner: 2,491,638 Coastlands GP: 2,491,638 Matthew D. Perry: 2,491,638
	(iii) Sole power to dispose or to direct the disposition of: Coastlands: 0 Partnership: 0 General Partner: 0 Coastlands GP: 0 Matthew D. Perry: 0
	(iv) Shared power to dispose or to direct the disposition of: Coastlands: 2,491,638 Partnership: 2,491,638 General Partner: 2,491,638 Coastlands GP: 2,491,638 Matthew D. Perry: 2,491,638
Item 5.	Ownership of 5 Percent or Less of a Class.
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. The Partnership holds the shares of Common Stock issuable upon exercise of pre-funded warrants, for the benefit of its investors and has the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, shares of Common Stock, including shares of Common Stock issuable upon exercise of pre-funded warrants.
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
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 acquired and are held in the ordinary course of business and 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. 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.

Coastlands Capital LP

Signature:	/s/ Mark Shamia
Name/Title:	Chief Operating Officer of the General Partner, Coastlands Capital LLC
Date:	10/03/2025

Coastlands Capital Partners LP

Signature:	/s/ Mark Shamia
Name/Title:	Chief Operating Officer of the General Partner, Coastlands Capital GP LLC
Date:	10/03/2025

Coastlands Capital GP LLC

Signature:	/s/ Mark Shamia
Name/Title:	Chief Operating Officer
Date:	10/03/2025

Coastlands Capital LLC

Signature:	/s/ Mark Shamia
Name/Title:	Chief Operating Officer
Date:	10/03/2025

Matthew D. Perry

Signature:	/s/ Matthew D. Perry
Name/Title:	Reporting person
Date:	10/03/2025

Exhibit Information

Exhibit 99.1 - Agreement Regarding Joint Filing of Statement on Schedule 13D or 13G (incorporated by reference to Exhibit 99.1 to the Schedule 13D filed on August 18, 2025)

FAQ

What percentage of XFOR does Coastlands report owning?

Coastlands and affiliates report beneficial ownership of 9.99% of X4 Pharmaceuticals’ common stock.

How many XFOR shares are beneficially owned by Coastlands?

The filing reports 2,491,638 shares beneficially owned, with shared voting and dispositive power over that amount.

Does the reported amount include warrant shares?

Yes. It includes shares issuable upon exercise of pre-funded warrants, subject to a 9.99% beneficial ownership limitation.

What share count did they use to calculate ownership?

They used 22,449,689 shares outstanding as of August 13, 2025, cited from an issuer registration statement.

Is the filing passive or for control purposes?

The certification states the securities were acquired and are held in the ordinary course and not to change or influence control.

Who are the reporting persons in the 13G for XFOR?

Coastlands Capital LP, Coastlands Capital Partners LP, Coastlands Capital GP LLC, Coastlands Capital LLC, and Matthew D. Perry.

What voting/dispositive powers are reported?

They report 0 sole voting/dispositive power and 2,491,638 shares of shared voting and dispositive power.