Kevin Bitterman - 12 Dec 2025 Form 4 Insider Report for Disc Medicine, Inc. (IRON)

Role: Director
Signature: /s/ Ommer Chohan, Attorney-in-Fact
Issuer symbol: IRON
Transactions as of: 12 Dec 2025
Net transactions value: -$16,764,139
Form type: 4
Filing time: 16 Dec 2025, 21:43:15 UTC
Previous filing: 17 Oct 2025
Next filing: 18 Dec 2025
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Bitterman Kevin	Director	C/O DISC MEDICINE, INC., 321 ARSENAL STREET, SUITE 101, WATERTOWN	/s/ Ommer Chohan, Attorney-in-Fact	16 Dec 2025	0001591747

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	IRON	Common Stock	Sale	$1,509,896	-16,403	-3.7%	$92.05	425,633	12 Dec 2025	See footnote	F1, F2
transaction	IRON	Common Stock	Sale	$356,618	-3,852	-0.91%	$92.58	421,781	12 Dec 2025	See footnote	F2, F3
transaction	IRON	Common Stock	Sale	$323,235	-3,446	-0.82%	$93.80	418,335	12 Dec 2025	See footnote	F2, F4
transaction	IRON	Common Stock	Sale	$784,910	-8,527	-2.2%	$92.05	377,022	12 Dec 2025	See footnote	F1, F5
transaction	IRON	Common Stock	Sale	$185,623	-2,005	-0.53%	$92.58	375,017	12 Dec 2025	See footnote	F3, F5
transaction	IRON	Common Stock	Sale	$168,183	-1,793	-0.48%	$93.80	373,224	12 Dec 2025	See footnote	F4, F5
transaction	IRON	Common Stock	Sale	$604,768	-6,570	-13%	$92.05	44,430	12 Dec 2025	See footnote	F1, F6
transaction	IRON	Common Stock	Sale	$142,573	-1,540	-3.5%	$92.58	42,890	12 Dec 2025	See footnote	F3, F6
transaction	IRON	Common Stock	Sale	$128,600	-1,371	-3.2%	$93.80	41,519	12 Dec 2025	See footnote	F4, F6
transaction	IRON	Common Stock	Sale	$2,636,287	-28,913	-6.9%	$91.18	389,422	15 Dec 2025	See footnote	F2, F7
transaction	IRON	Common Stock	Sale	$360,771	-3,921	-1%	$92.01	385,501	15 Dec 2025	See footnote	F2, F8
transaction	IRON	Common Stock	Sale	$1,350,467	-14,811	-4%	$91.18	358,413	15 Dec 2025	See footnote	F5, F7
transaction	IRON	Common Stock	Sale	$188,528	-2,049	-0.57%	$92.01	356,364	15 Dec 2025	See footnote	F5, F8
transaction	IRON	Common Stock	Sale	$1,041,914	-11,427	-28%	$91.18	30,092	15 Dec 2025	See footnote	F6, F7
transaction	IRON	Common Stock	Sale	$144,640	-1,572	-5.2%	$92.01	28,520	15 Dec 2025	See footnote	F6, F8
transaction	IRON	Common Stock	Options Exercise	$94,500	+7,000		$13.50	7,000	15 Dec 2025	Direct
transaction	IRON	Common Stock	Sale	$643,090	-7,000	-100%	$91.87	0	15 Dec 2025	Direct	F9
transaction	IRON	Common Stock	Sale	$3,275,334	-35,898	-9.3%	$91.24	349,603	16 Dec 2025	See footnote	F2, F10
transaction	IRON	Common Stock	Sale	$1,703,086	-18,666	-5.2%	$91.24	337,698	16 Dec 2025	See footnote	F5, F10
transaction	IRON	Common Stock	Sale	$1,310,115	-14,359	-50%	$91.24	14,161	16 Dec 2025	See footnote	F6, F10

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
transaction	IRON	Stock Option (Right to Buy)	Options Exercise	$0	-7,000	-100%	$0.000000	0	15 Dec 2025	Common Stock	7,000	$13.50	Direct	F11

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	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).
F2	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.
F3	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.
F4	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.
F5	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.
F6	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.
F7	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.
F8	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.
F9	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.
F10	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.
F11	Fully Vested.