Statement of Changes in Beneficial Ownership (Form 4)

FORM 4 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 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * RA CAPITAL MANAGEMENT, L.P. 2. Issuer Name and Ticker or Trading Symbol Hemab Therapeutics Holdings, Inc. [COAG] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 200 BERKELEY STREET, 18TH FLOOR, 3. Date of Earliest Transaction (Month/Day/Year) 05/04/2026 (Street) BOSTON, MA 02116 4. If Amendment, Date Original Filed (Month/Day/Year) 6. Individual or Joint/Group Filing (Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person (City) (State) (Zip) 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 05/04/2026 C 3,607,846 A (1) 3,607,846 I See footnotes(2)(3) Common Stock 05/04/2026 C 1,009,052 A (1) 1,009,052 I See footnotes(2)(4) Common Stock 05/04/2026 C 221,188 A (1) 221,188 I See footnotes(2)(5) Common Stock 05/04/2026 P 2,541,250 A $18 6,149,096 I See footnotes(2)(3) Common Stock 05/04/2026 P 133,750 A $18 354,938 I See footnotes(2)(5) Common Stock 05/05/2026 P 87,143 A $24.59(6) 6,236,239 I See footnotes(2)(3) Common Stock 05/05/2026 P 10,268 A $25 6,246,507 I See footnotes(2)(3) Common Stock 05/06/2026 P 14,611 A $23.77(7) 6,261,118 I See footnotes(2)(3) Common Stock 05/06/2026 P 53,407 A $24.83(8) 6,314,525 I See footnotes(2)(3)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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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 Underlying Securities (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 of Derivative Security: 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
Series A Preferred Stock	(1)	05/04/2026		C			64,680	(1)	(1)	Common Stock	1,422,960	(1)	0	I	See footnotes(2)(3)
Series A Preferred Stock	(1)	05/04/2026		C			27,720	(1)	(1)	Common Stock	609,840	(1)	0	I	See footnotes(2)(4)
Series B Preferred Stock	(1)	05/04/2026		C			42,341	(1)	(1)	Common Stock	931,502	(1)	0	I	See footnotes(2)(3)
Series B Preferred Stock	(1)	05/04/2026		C			18,146	(1)	(1)	Common Stock	399,212	(1)	0	I	See footnotes(2)(4)
Series C Preferred Stock	(1)	05/04/2026		C			56,972	(1)	(1)	Common Stock	1,253,384	(1)	0	I	See footnotes(2)(3)
Series C Preferred Stock	(1)	05/04/2026		C			10,054	(1)	(1)	Common Stock	221,188	(1)	0	I	See footnotes(2)(5)

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
RA CAPITAL MANAGEMENT, L.P. 200 BERKELEY STREET, 18TH FLOOR BOSTON, MA 02116	X	X
RA Capital Healthcare Fund LP C/O RA CAPITAL MANAGEMENT, L.P. 200 BERKELEY STREET, 18TH FLOOR BOSTON, MA 02116	X	X
RA Capital Nexus Fund II, L.P. C/O RA CAPITAL MANAGEMENT, L.P. 200 BERKELEY STREET, 18TH FLOOR BOSTON, MA 02116	X
RA Capital Nexus Fund IV, L.P. C/O RA CAPITAL MANAGEMENT, L.P. 200 BERKELEY STREET, 18TH FLOOR BOSTON, MA 02116	X
Kolchinsky Peter C/O RA CAPITAL MANAGEMENT, L.P. 200 BERKELEY STREET, 18TH FLOOR BOSTON, MA 02116	X	X
Shah Rajeev M. C/O RA CAPITAL MANAGEMENT, L.P. 200 BERKELEY STREET, 18TH FLOOR BOSTON, MA 02116	X	X

Signatures

/s/ Peter Kolchinsky, Manager of RA Capital Management, L.P.		05/06/2026
**Signature of Reporting Person		Date
/s/ Peter Kolchinsky, Manager of RA Capital Healthcare Fund GP, LLC the General Partner of RA Capital Healthcare Fund, L.P.		05/06/2026
**Signature of Reporting Person		Date
/s/ Peter Kolchinsky, Manager of RA Capital Nexus Fund II GP, LLC, the General Partner of RA Capital Nexus Fund II, L.P.		05/06/2026
**Signature of Reporting Person		Date
/s/ Peter Kolchinsky, Manager of RA Capital Nexus Fund IV GP, LLC, the General Partner of RA Capital Nexus Fund IV, L.P.		05/06/2026
**Signature of Reporting Person		Date
/s/ Peter Kolchinsky, individually		05/06/2026
**Signature of Reporting Person		Date
/s/ Rajeev Shah, individually		05/06/2026
**Signature of Reporting Person		Date

Explanation of Responses:

*	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).
(1)	Each share of Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock automatically converted into shares of Common Stock immediately prior to the closing of the Issuer's initial public offering for no additional consideration, on a 22-for-1 basis, and had no expiration date.
(2)	RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund"), RA Capital Nexus II Fund, L.P. (the "Nexus Fund II") and RA Capital Nexus IV Fund, L.P. (the "Nexus Fund IV"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. The Adviser, the Adviser GP, the Fund, the Nexus Fund II, the Nexus Fund IV, Dr. Kolchinsky and Mr. Shah disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.
(3)	Held directly by the Fund.
(4)	Held directly by Nexus Fund II.
(5)	Held directly by Nexus Fund IV.
(6)	The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $24.00 to $24.9994 inclusive. The Reporting Persons undertake to provide to 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 purchased at each separate price within the range set forth in this footnote.
(7)	The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $23.495 to $24.455 inclusive. The Reporting Persons undertake to provide to 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 purchased at each separate price within the range set forth in this footnote.
(8)	The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $24.505 to $25.00 inclusive. The Reporting Persons undertake to provide to 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 purchased at each separate price within the range set forth in this footnote.
Remarks: Dr. Laura Tadvalkar, a Managing Director of the Adviser, serves on the Issuer's board of directors.

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