[Form 4] Disc Medicine, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Disc Medicine director Kevin Bitterman reported sales of company common stock under a Rule 10b5-1 plan. The Form 4 shows sales on 08/13/2025 of 24,962 shares at a weighted-average price of $61.15 and on 08/14/2025 of 7,212 shares at a weighted-average price of $60.99, conducted pursuant to a 10b5-1 trading plan dated January 31, 2025. The filing lists substantial indirect holdings attributed to investment vehicles: 600,120 shares following the 08/13 sale and 592,908 shares following the 08/14 sale, plus additional holdings of 420,549 shares and 51,000 shares held by named funds. The report was signed by an attorney-in-fact on 08/15/2025.

Positive

• Sales executed under a documented Rule 10b5-1 trading plan, indicating pre-arranged transactions and adherence to insider trading procedures
• Detailed disclosure of indirect ownership structure through named Atlas Venture funds and partners, improving transparency

Negative

• Reporting person sold 32,174 shares across two days at weighted-average prices around $61, which reduces their direct/indirect stake reported on the form

Insights

Financial Analyst

TL;DR Insider sales were executed under a 10b5-1 plan; reported holdings remain substantial.

The reported dispositions total 32,174 shares sold across two dates at weighted-average prices of $61.15 and $60.99. These sales were made pursuant to a documented 10b5-1 plan, which indicates pre-arranged trading and reduces the likelihood that the transactions reflect opportunistic reactions to nonpublic company developments. The Form 4 also discloses large indirect positions held through multiple Atlas Venture funds, with reported post-sale beneficial ownership figures in the hundreds of thousands of shares.

Corporate Governance Expert

TL;DR Transactions were pre-planned under a 10b5-1 program and properly disclosed on Form 4.

From a governance and compliance perspective, the filing identifies the use of a 10b5-1 trading plan dated January 31, 2025, and includes the required explanatory footnotes describing indirect holdings through related investment entities. The filing appears to follow disclosure conventions by reporting weighted-average prices and providing the chain of entity ownership for indirect holdings. No amendments or additional tones of noncompliance are recorded in the form provided.

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).

X

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^*

Bitterman Kevin

(Last) (First) (Middle)

C/O DISC MEDICINE, INC.

321 ARSENAL STREET, SUITE 101

(Street)

WATERTOWN MA 02472

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Disc Medicine, Inc. [ IRON ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
08/13/2025

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

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

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

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	08/13/2025		S(1)		24,962	D	$61.15(2)	600,120	I	See footnote(3)
Common Stock	08/14/2025		S(1)		7,212	D	$60.99(4)	592,908	I	See footnote(3)
Common Stock								420,549	I	See footnote(5)
Common Stock								51,000	I	See footnote(6)

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. Shares were sold pursuant to a Rule 10b5-1 trading plan dated January 31, 2025.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $60.95 to $61.615 inclusive. The Reporting Person undertakes 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 sold at each separate price within the ranges set forth in footnotes (2) and (4).

3. These shares are held by Atlas Venture Opportunity Fund I, LP ("Opportunity I"). The general partner of Opportunity I is Atlas Venture Associates Opportunity I, LP ("Associates I"). Atlas Venture Associates Opportunity I, LLC ("Associates I LLC") is the general partner of Associates I. The Reporting Person is a member of Associates I LLC and disclaims beneficial ownership of such securities held by Opportunity I, except to the extent of his pecuniary interest therein, if any.

4. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $60.95 to $61.11 inclusive.

5. These shares are held by Atlas Venture Opportunity Fund II, LP ("Opportunity II"). The general partner of Opportunity II is Atlas Venture Associates Opportunity II, LP ("Associates II"). Atlas Venture Associates Opportunity II, LLC ("Associates II LLC") is the general partner of Associates II. The Reporting Person is a member of Associates II LLC and disclaims beneficial ownership of such securities held by Opportunity II, except to the extent of his pecuniary interest therein, if any.

6. These shares are held by Atlas Venture Fund XII, L.P. ("Atlas XII"). The general partner of Atlas XII is Atlas Venture Associates XII, L.P. ("Associates XII"). Atlas Venture Associates XII, LLC ("Associates XII LLC") is the general partner of Associates XII. The Reporting Person is a member of Associates XII LLC and disclaims beneficial ownership of such securities held by Atlas XII, except to the extent of his pecuniary interest therein, if any.

	/s/ Ommer Chohan, Attorney-in-Fact	08/15/2025
	** 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.

FAQ

What transactions did Kevin Bitterman report on the Form 4 for IRON?

He reported dispositions of 24,962 shares on 08/13/2025 at a weighted-average price of $61.15 and 7,212 shares on 08/14/2025 at $60.99.

Were the sales made pursuant to a 10b5-1 plan?

Yes. The filing states the shares were sold pursuant to a Rule 10b5-1 trading plan dated January 31, 2025.

What beneficial ownership remains after the reported transactions?

The Form 4 reports indirect holdings of 600,120 shares after the 08/13 sale and 592,908 shares after the 08/14 sale, plus additional reported holdings of 420,549 shares and 51,000 shares held by named funds.

Who signed the Form 4 and when?

The form was signed by Ommer Chohan, Attorney-in-Fact, on 08/15/2025.