RA Capital funds lift Hemab Therapeutics (COAG) stake, convert preferred stock

Rhea-AI Filing Summary

Hemab Therapeutics Holdings, Inc. reported that funds managed by RA Capital increased their indirect stake through a mix of open‑market purchases and preferred stock conversions. Over May 4–6, 2026, the funds bought 2,840,429 shares of common stock at prices including $18.00, $24.59, $25.00, $23.77 and $24.83 per share. In connection with the issuer’s initial public offering, all Series A, B and C preferred shares automatically converted to common stock on a 22‑for‑1 basis for no additional consideration. Following these transactions, indirect holdings reported in one line reached 6,314,525 shares of common stock.

Insider Trade Summary

Net Buyer: 2,840,429 shares ($52,222,946)

Net Buy 15 txns

Insider RA CAPITAL MANAGEMENT, L.P., RA Capital Healthcare Fund LP, RA Capital Nexus Fund II, L.P., RA Capital Nexus Fund IV, L.P., Kolchinsky Peter, Shah Rajeev M.

Role null | null | null | null | null | null

Bought 2,840,429 shs ($52.22M)

Type	Security	Shares	Price	Value
Purchase	Common Stock	14,611	$23.77	$347K
Purchase	Common Stock	53,407	$24.83	$1.33M
Purchase	Common Stock	87,143	$24.59	$2.14M
Purchase	Common Stock	10,268	$25.00	$257K
Conversion	Series A Preferred Stock	64,680	$0.00	--
Conversion	Series A Preferred Stock	27,720	$0.00	--
Conversion	Series B Preferred Stock	42,341	$0.00	--
Conversion	Series B Preferred Stock	18,146	$0.00	--
Conversion	Series C Preferred Stock	56,972	$0.00	--
Conversion	Series C Preferred Stock	10,054	$0.00	--
Conversion	Common Stock	3,607,846	$0.00	--
Conversion	Common Stock	1,009,052	$0.00	--
Conversion	Common Stock	221,188	$0.00	--
Purchase	Common Stock	2,541,250	$18.00	$45.74M
Purchase	Common Stock	133,750	$18.00	$2.41M

Holdings After Transaction: Common Stock — 6,261,118 shares (Indirect, See footnotes); Series A Preferred Stock — 0 shares (Indirect, See footnotes); Series B Preferred Stock — 0 shares (Indirect, See footnotes); Series C Preferred Stock — 0 shares (Indirect, See footnotes)

Footnotes (1)

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. 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. Held directly by the Fund. Held directly by Nexus Fund II. Held directly by Nexus Fund IV. 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. 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. 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.

Key Figures

Open-market purchases: 2,840,429 shares Highest reported purchase price: $25.00 per share Large single-day buy: 2,541,250 shares at $18.00 +5 more

8 metrics

Open-market purchases 2,840,429 shares Net common stock bought May 4–6, 2026

Highest reported purchase price $25.00 per share Common stock transaction on May 5, 2026

Large single-day buy 2,541,250 shares at $18.00 Common stock purchased May 4, 2026 across two lines

Conversion ratio 22-for-1 Series A, B, C preferred converting to common before IPO

Indirect holdings after trade 6,314,525 shares Common stock held indirectly after May 6, 2026 purchase

Series C conversion block 1,253,572 common shares 221,188 and 1,253,384 underlying shares from Series C preferred

Series B conversion block 1,330,714 common shares 399,212 and 931,502 underlying shares from Series B preferred

Series A conversion block 2,032,800 common shares 609,840 and 1,422,960 underlying shares from Series A preferred

Key Terms

weighted average price, initial public offering, pecuniary interest, derivative security, +1 more

5 terms

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.

initial public offering financial

"converted into shares of Common Stock immediately prior to the closing of the Issuer's initial public offering"

An initial public offering (IPO) is when a private company first sells its shares to the public and becomes a stock-listed company. It matters because it allows the company to raise money from a wide range of investors, helping it grow, while giving early shareholders a way to sell some of their ownership.

pecuniary interest financial

"disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein"

derivative security financial

"Conversion of derivative security"

A derivative security is a financial contract whose value comes from the price or performance of something else, such as a stock, bond, commodity, or market index. For investors it acts like an insurance policy or a wager: it can be used to protect against losses, lock in prices, or amplify gains and losses, so it can change a portfolio’s risk and potential return without owning the underlying asset directly.

conversion of derivative security financial

"transaction_code_description": "Conversion of derivative security""

Form 4 Insider Transactions: What Each Field Means →

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^*

RA CAPITAL MANAGEMENT, L.P.

(Last) (First) (Middle)

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

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)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/04/2026

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

	Form filed by One Reporting Person
X	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	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)

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
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)

1. Name and Address of Reporting Person^*

RA CAPITAL MANAGEMENT, L.P.

(Last) (First) (Middle)

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

RA Capital Healthcare Fund LP

(Last) (First) (Middle)

C/O RA CAPITAL MANAGEMENT, L.P.

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

RA Capital Nexus Fund II, L.P.

(Last) (First) (Middle)

C/O RA CAPITAL MANAGEMENT, L.P.

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

RA Capital Nexus Fund IV, L.P.

(Last) (First) (Middle)

C/O RA CAPITAL MANAGEMENT, L.P.

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Kolchinsky Peter

(Last) (First) (Middle)

C/O RA CAPITAL MANAGEMENT, L.P.

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Shah Rajeev M.

(Last) (First) (Middle)

C/O RA CAPITAL MANAGEMENT, L.P.

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

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

Explanation of Responses:

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.

	/s/ Peter Kolchinsky, Manager of RA Capital Management, L.P.	05/06/2026
	/s/ Peter Kolchinsky, Manager of RA Capital Healthcare Fund GP, LLC the General Partner of RA Capital Healthcare Fund, L.P.	05/06/2026
	/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
	/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
	/s/ Peter Kolchinsky, individually	05/06/2026
	/s/ Rajeev Shah, individually	05/06/2026
	** 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)

FAQ

What insider activity did RA Capital report in Hemab Therapeutics (COAG)?

RA Capital-managed funds reported open-market purchases and preferred stock conversions in Hemab Therapeutics. They acquired common shares through multiple buys in early May 2026 and automatic 22-for-1 conversions of Series A, B and C preferred stock immediately before the company’s initial public offering.

How many Hemab Therapeutics (COAG) shares did RA Capital funds buy?

RA Capital’s filing shows net open-market purchases of 2,840,429 shares of Hemab Therapeutics common stock. These buys occurred across several transactions dated May 4–6, 2026, at different prices, and increased the funds’ indirect ownership position in the company’s common shares.

At what prices were Hemab Therapeutics (COAG) shares purchased by RA Capital funds?

Individual transactions list prices such as $18.00, $24.59, $25.00, $23.77 and $24.83 per share. Footnotes explain some reported prices are weighted averages for trades executed in ranges, with detailed breakdowns available upon request from the reporting persons.

What happened to Hemab Therapeutics (COAG) preferred stock in this Form 4?

All Series A, Series B and Series C preferred stock automatically converted into Hemab Therapeutics common stock immediately before the initial public offering. The conversion occurred at a 22-for-1 ratio for no additional consideration and the preferred shares had no expiration date before conversion.

Who actually holds the Hemab Therapeutics (COAG) shares reported by RA Capital?

The shares are held by RA Capital funds, including RA Capital Healthcare Fund LP, RA Capital Nexus II Fund LP and RA Capital Nexus IV Fund LP. RA Capital Management, L.P. and related parties disclaim beneficial ownership beyond their pecuniary interest in these securities, according to the filing’s footnotes.

What was the resulting Hemab Therapeutics (COAG) position after these RA Capital transactions?

One reported line shows indirect holdings of 6,314,525 Hemab Therapeutics common shares following a May 6, 2026 purchase. Other lines show different post-transaction share counts for specific entities, reflecting positions held by individual RA Capital-managed funds after the various buys and conversions.