X4 Pharmaceuticals CFO sells 11,767 shares

The shares were sold in multiple transactions at prices ranging from $2.82 to $2.92, inclusive.

Rhea-AI Filing Summary

X4 Pharmaceuticals, Inc. Chief Financial Officer David Kirske reported selling 11,767 shares of common stock on October 1, 2026, at a weighted average price of $2.8604 per share. The sale covered a personal income tax obligation upon settlement of a restricted stock unit award. No Rule 10b5-1 plan is reported. His reported holdings afterward were 155,983 shares, including 64,418 shares that represent restricted stock units.

Insider Trade Summary

Net Seller: 11,767 shares

Net Sell 1 txn

Insider KIRSKE DAVID

Role Chief Financial Officer

Sold 11,767 shs ($34K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1, F2, F3	11,767	$2.8604	$34K

Holdings After Transaction: Common Stock — 155,983 shares (Direct)

Footnotes (3)

1. F1. Sale of shares to cover personal income tax obligation upon settlement of restricted stock unit award.
2. F2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $2.82 to $2.92, inclusive. The Reporting Person undertakes to provide the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
3. F3. Of the shares of common stock reported, 64,418 shares represent restricted stock units.

Key Figures

Shares sold: 11,767 shares Weighted average sale price: $2.8604 per share Sale price range: $2.82 to $2.92 per share +2 more

5 metrics

Shares sold 11,767 shares October 1, 2026

Weighted average sale price $2.8604 per share October 1, 2026

Sale price range $2.82 to $2.92 per share Multiple transactions; inclusive

Reported shares held after transaction 155,983 shares After the October 1, 2026 transaction

Restricted stock units included in reported common stock 64,418 shares Reported after the transaction

Key Terms

restricted stock unit award, weighted average price, Rule 10b5-1 plan

3 terms

restricted stock unit award financial

"settlement of restricted stock unit award"

A restricted stock unit award is a promise by a company to give an employee a specified number of company shares at a future date if certain conditions are met, such as staying with the company or hitting performance goals. For investors, these awards matter because they can increase the total number of shares outstanding when converted, diluting existing holders, and they align employees’ incentives with shareholders’ interests much like giving a rising bonus that becomes real only after conditions are satisfied.

weighted average price financial

"The price reported in Column 4 is a weighted average price"

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

Rule 10b5-1 plan regulatory

"no Rule 10b5-1 plan is reported"

A Rule 10b5-1 plan is a prearranged, written schedule that lets corporate insiders buy or sell company stock at set times or amounts, even if they later learn material nonpublic information. Think of it like setting an automatic thermostat for trades: it creates a clear record that trades were planned in advance, reducing the risk of insider-trading accusations and helping investors trust that insider transactions are routine rather than based on secret information.

FAQ

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

How many XFOR shares did the CFO sell, and at what price?

David Kirske sold 11,767 shares on October 1, 2026, at a weighted average price of $2.8604 per share. The shares were sold in multiple transactions ranging from $2.82 to $2.92, inclusive, to cover a personal income tax obligation upon settlement of a restricted stock unit award; no Rule 10b5-1 plan is reported.

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

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Available on EDGAR 10/05/2026 - 04:03 PM Accepted by SEC EDGAR 10/05/2026 - 04:03 PM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

KIRSKE DAVID

(Last) (First) (Middle)

C/O X4 PHARMACEUTICALS INC.

61 N BEACON STREET, 4TH FLOOR

(Street)

BOSTON MASSACHUSETTS 02134

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
X4 Pharmaceuticals, Inc [ XFOR ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Financial Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
10/01/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	10/01/2026		S(1)		11,767	D	$2.8604(2)	155,983(3)	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. Sale of shares to cover personal income tax obligation upon settlement of restricted stock unit award.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $2.82 to $2.92, inclusive. The Reporting Person undertakes to provide the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

3. Of the shares of common stock reported, 64,418 shares represent restricted stock units.

Remarks:

	/s/ Mitch Buckley, attorney-in-fact	10/05/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)