Disc Medicine (NASDAQ: IRON) director reports indirect share sales via funds

Rhea-AI Filing Summary

Disc Medicine, Inc. director reported several small sales of the company’s common stock on 12/17/2025. The transactions involved indirect holdings through Atlas Venture-managed funds. One fund sold 393 shares, leaving 349,210 shares beneficially owned following the sale. A second fund sold 213 shares, with 337,485 shares remaining, and a third fund sold 148 shares, with 14,013 shares remaining.

The weighted average sale price reported for these trades was $91.47 per share, with individual trades executed between $91.2501 and $91.52. The director reports these positions as indirectly owned through Atlas Venture Opportunity Fund I, Atlas Venture Opportunity Fund II, and Atlas Venture Fund XII and disclaims beneficial ownership beyond any pecuniary interest.

Insider Trade Summary

Net Seller: 754 shares ($68,968)

Net Sell 3 txns

Insider Bitterman Kevin

Role Director

Sold 754 shs ($69K)

Type	Security	Shares	Price	Value
Sale	Common Stock	393	$91.47	$36K
Sale	Common Stock	213	$91.47	$19K
Sale	Common Stock	148	$91.47	$14K

Holdings After Transaction: Common Stock — 349,210 shares (Indirect, See footnote)

Footnotes (1)

1. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $91.2501 to $91.52 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 range set forth in footnote. 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. 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. 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.

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^*

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)
12/17/2025

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	12/17/2025		S		393	D	$91.47(1)	349,210	I	See footnote(2)
Common Stock	12/17/2025		S		213	D	$91.47(1)	337,485	I	See footnote(3)
Common Stock	12/17/2025		S		148	D	$91.47(1)	14,013	I	See footnote(4)

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. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $91.2501 to $91.52 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 range set forth in footnote.

2. 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.

3. 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.

4. 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	12/18/2025
	** 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 insider transaction did Disc Medicine (IRON) disclose in this Form 4?

The filing reports that a director of Disc Medicine, Inc. sold small amounts of common stock on 12/17/2025 through several Atlas Venture investment funds.

How many Disc Medicine (IRON) shares were sold in the reported transactions?

The reported transactions show sales of 393 shares, 213 shares, and 148 shares of common stock, all on 12/17/2025.

What prices were the Disc Medicine (IRON) shares sold for in this Form 4?

The weighted average sale price reported was $91.47 per share, with individual trades taking place between $91.2501 and $91.52.

How many Disc Medicine (IRON) shares does the reporting person beneficially own after these sales?

After the transactions, the filing shows 349,210 shares, 337,485 shares, and 14,013 shares beneficially owned indirectly through three separate Atlas Venture funds.

Are the Disc Medicine (IRON) shares held directly or indirectly by the reporting person?

The shares are reported as held indirectly through Atlas Venture Opportunity Fund I, Atlas Venture Opportunity Fund II, and Atlas Venture Fund XII, with the director noting membership interests in their general partners.

Does the reporting person claim full beneficial ownership of the Disc Medicine (IRON) shares held by the funds?

No. The director disclaims beneficial ownership of securities held by each Atlas Venture fund, except to the extent of any pecuniary interest.

What is the reporting person’s relationship to Disc Medicine (IRON)?

The individual is identified in the filing as a director of Disc Medicine, Inc..