Disc Medicine (IRON) director details multi-day stock sales and option exercise

Rhea-AI Filing Summary

A director of Disc Medicine, Inc. reported multiple December 2025 transactions in the company’s common stock. The filing lists several sales coded 'S' on 12/12, 12/15, and 12/16/2025 at weighted average prices including $92.05, $92.58, $93.8, $91.18, $92.01, $91.87, and $91.24 per share.

On 12/15/2025 the director exercised a fully vested stock option for 7,000 shares at an exercise price of $13.5 per share and sold those 7,000 shares the same day at a weighted average price of $91.87 per share. After the 12/16/2025 sales, the director reports indirect beneficial ownership of 349,603 Disc Medicine shares through Atlas Venture Opportunity Fund I, 337,698 shares through Atlas Venture Opportunity Fund II, and 14,161 shares through Atlas Venture Fund XII, while disclaiming beneficial ownership beyond any pecuniary interest.

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

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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)
12/12/2025

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	12/12/2025		S		16,403	D	$92.05(1)	425,633	I	See footnote(2)
Common Stock	12/12/2025		S		3,852	D	$92.58(3)	421,781	I	See footnote(2)
Common Stock	12/12/2025		S		3,446	D	$93.8(4)	418,335	I	See footnote(2)
Common Stock	12/12/2025		S		8,527	D	$92.05(1)	377,022	I	See footnote(5)
Common Stock	12/12/2025		S		2,005	D	$92.58(3)	375,017	I	See footnote(5)
Common Stock	12/12/2025		S		1,793	D	$93.8(4)	373,224	I	See footnote(5)
Common Stock	12/12/2025		S		6,570	D	$92.05(1)	44,430	I	See footnote(6)
Common Stock	12/12/2025		S		1,540	D	$92.58(3)	42,890	I	See footnote(6)
Common Stock	12/12/2025		S		1,371	D	$93.8(4)	41,519	I	See footnote(6)
Common Stock	12/15/2025		S		28,913	D	$91.18(7)	389,422	I	See footnote(2)
Common Stock	12/15/2025		S		3,921	D	$92.01(8)	385,501	I	See footnote(2)
Common Stock	12/15/2025		S		14,811	D	$91.18(7)	358,413	I	See footnote(5)
Common Stock	12/15/2025		S		2,049	D	$92.01(8)	356,364	I	See footnote(5)
Common Stock	12/15/2025		S		11,427	D	$91.18(7)	30,092	I	See footnote(6)
Common Stock	12/15/2025		S		1,572	D	$92.01(8)	28,520	I	See footnote(6)
Common Stock	12/15/2025		M		7,000	A	$13.5	7,000	D
Common Stock	12/15/2025		S		7,000	D	$91.87(9)	0	D
Common Stock	12/16/2025		S		35,898	D	$91.24(10)	349,603	I	See footnote(2)
Common Stock	12/16/2025		S		18,666	D	$91.24(10)	337,698	I	See footnote(5)
Common Stock	12/16/2025		S		14,359	D	$91.24(10)	14,161	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
Stock Option (Right to Buy)	$13.5	12/15/2025		M			7,000	(11)	12/28/2032	Common Stock	7,000	$0	0	D

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 $91.5289 to $92.4325 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 (1), (3), (4), (7), (8), (9) and (10).

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. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $92.52 to $93.3796 inclusive.

4. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $93.52 to $94.255 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.

7. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $91.00 to $91.99 inclusive.

8. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $92.00 to $92.48 inclusive.

9. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $91.79 to $91.95 inclusive.

10. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $91.00 to $91.705 inclusive.

11. Fully Vested.

	/s/ Ommer Chohan, Attorney-in-Fact	12/16/2025
	** 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.
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FAQ

What insider stock activity did Disc Medicine (IRON) report in this Form 4?

The report shows a Disc Medicine, Inc. director engaging in multiple December 2025 transactions in common stock, mainly sales by affiliated Atlas Venture funds plus one stock option exercise and related sale.

What stock sales did the Disc Medicine director report on December 12, 2025?

On 12/12/2025, the director reported several common stock sales coded 'S' at weighted average prices of $92.05, $92.58, and $93.8 per share, with shares held indirectly through Atlas Venture Opportunity Fund I, Opportunity Fund II, and Atlas Venture Fund XII.

What transactions occurred on December 15, 2025 for Disc Medicine (IRON)?

On 12/15/2025, the filing lists additional common stock sales at weighted average prices of $91.18 and $92.01 per share and a stock option exercise for 7,000 shares at an exercise price of $13.5, followed by a sale of those 7,000 shares at a weighted average price of $91.87 per share.

How many Disc Medicine shares remain indirectly held after the December 16, 2025 trades?

After the 12/16/2025 sales, the director reports indirect beneficial ownership of 349,603 shares through Atlas Venture Opportunity Fund I, 337,698 shares through Atlas Venture Opportunity Fund II, and 14,161 shares through Atlas Venture Fund XII.

What does the stock option disclosure show in the Disc Medicine Form 4?

Table II shows a fully vested stock option with an exercise price of $13.5 per share, exercisable into 7,000 shares of common stock and expiring on 12/28/2032. On 12/15/2025, this option was exercised for 7,000 shares.

How are the Atlas Venture funds related to the Disc Medicine director’s holdings?

The reported shares are held by Atlas Venture Opportunity Fund I, Atlas Venture Opportunity Fund II, and Atlas Venture Fund XII. The reporting person is a member of the entities that serve as general partners of these funds and disclaims beneficial ownership of their securities except to the extent of any pecuniary interest.

What do the weighted average price footnotes mean in this Disc Medicine filing?

Several sales prices in Column 4 are reported as weighted average prices, with footnotes stating that the shares were sold in multiple transactions within specified price ranges. The reporting person undertakes to provide full trade‑by‑trade pricing details to the issuer, its security holders, or the SEC staff upon request.