IRON

SEC source: 0001193125-26-393353 · ownership.xml · derivative · entry 2

Quisel John D · CIK 0001586788 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 150,120

Underlying: Common Stock · 36,000 shares

Expires 2030-03-10

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_date: The shares underlying this option are fully vested and exercisable as of the date hereof.

SEC source: 0001193125-26-393353 · ownership.xml · nonDerivative · entry 1

Quisel John D · CIK 0001586788 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 262,064

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001591747-26-000007 · form4-09152026_040930.xml · derivative · entry 10

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 10,000 shares

Expires 2035-06-10

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F5 · derivative.exercise_date: Fully vested and exercisable.

SEC source: 0001591747-26-000007 · form4-09152026_040930.xml · derivative · entry 9

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 10,000 shares

Expires 2034-06-11

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F5 · derivative.exercise_date: Fully vested and exercisable.

SEC source: 0001591747-26-000007 · form4-09152026_040930.xml · derivative · entry 8

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 7,136 shares

Expires 2033-06-08

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F5 · derivative.exercise_date: Fully vested and exercisable.

SEC source: 0001591747-26-000007 · form4-09152026_040930.xml · nonDerivative · entry 4

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

F1 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $70.10 to $70.37 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 this footnote.

SEC source: 0001591747-26-000007 · form4-09152026_040930.xml · nonDerivative · entry 3

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 27,136

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001591747-26-000007 · form4-09152026_040930.xml · nonDerivative · entry 2

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 17,136

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001591747-26-000007 · form4-09152026_040930.xml · nonDerivative · entry 1

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 7,136

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001591747-26-000005 · form4-09092026_080927.xml · nonDerivative · entry 3

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: Plan reported

Ownership: Indirect · See footnote

Disclosed balance after: 13,427

F1 · kind: Shares were sold pursuant to a Rule 10b5-1 trading plan adopted on July 30, 2026.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $79.95 to $79.98 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 this footnote.

F5 · ownership.nature: 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.

SEC source: 0001591747-26-000005 · form4-09092026_080927.xml · nonDerivative · entry 2

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: Plan reported

Ownership: Indirect · See footnote

Disclosed balance after: 312,230

F1 · kind: Shares were sold pursuant to a Rule 10b5-1 trading plan adopted on July 30, 2026.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $79.95 to $79.98 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 this footnote.

F4 · ownership.nature: These shares are held by Atlas Venture Opportunity Fund II, L.P. ("Opportunity II"). The general partner of Opportunity II is Atlas Venture Associates Opportunity II, L.P. ("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.

SEC source: 0001591747-26-000005 · form4-09092026_080927.xml · nonDerivative · entry 1

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: Plan reported

Ownership: Indirect · See footnote

Disclosed balance after: 318,866

F1 · kind: Shares were sold pursuant to a Rule 10b5-1 trading plan adopted on July 30, 2026.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $79.95 to $79.98 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 this footnote.

F3 · ownership.nature: These shares are held by Atlas Venture Opportunity Fund I, L.P. ("Opportunity I"). The general partner of Opportunity I is Atlas Venture Associates Opportunity I, L.P. ("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.

SEC source: 0001591747-26-000002 · form4-09032026_090939.xml · nonDerivative · entry 12

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: Plan reported

Ownership: Indirect · See footnote

Disclosed balance after: 13,445

F1 · kind: Shares were sold pursuant to a Rule 10b5-1 trading plan adopted on July 30, 2026.

F7 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $79.95 to $80.28 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 this footnote.

F4 · ownership.nature: 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.

SEC source: 0001591747-26-000002 · form4-09032026_090939.xml · nonDerivative · entry 11

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: Plan reported

Ownership: Indirect · See footnote

Disclosed balance after: 312,989

F1 · kind: Shares were sold pursuant to a Rule 10b5-1 trading plan adopted on July 30, 2026.

F7 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $79.95 to $80.28 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 this footnote.

F3 · ownership.nature: These shares are held by Atlas Venture Opportunity Fund II, L.P. ("Opportunity II"). The general partner of Opportunity II is Atlas Venture Associates Opportunity II, L.P. ("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.

SEC source: 0001591747-26-000002 · form4-09032026_090939.xml · nonDerivative · entry 10

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: Plan reported

Ownership: Indirect · See footnote

Disclosed balance after: 319,778

F1 · kind: Shares were sold pursuant to a Rule 10b5-1 trading plan adopted on July 30, 2026.

F7 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $79.95 to $80.28 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 this footnote.

F2 · ownership.nature: These shares are held by Atlas Venture Opportunity Fund I, L.P. ("Opportunity I"). The general partner of Opportunity I is Atlas Venture Associates Opportunity I, L.P. ("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.

SEC source: 0001591747-26-000002 · form4-09032026_090939.xml · nonDerivative · entry 9

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: Plan reported

Ownership: Indirect · See footnote

Disclosed balance after: 13,499

F1 · kind: Shares were sold pursuant to a Rule 10b5-1 trading plan adopted on July 30, 2026.

F6 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $80.9677 to $81.0079 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 this footnote.

F4 · ownership.nature: 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.

SEC source: 0001591747-26-000002 · form4-09032026_090939.xml · nonDerivative · entry 8

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: Plan reported

Ownership: Indirect · See footnote

Disclosed balance after: 315,328

F1 · kind: Shares were sold pursuant to a Rule 10b5-1 trading plan adopted on July 30, 2026.

F6 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $80.9677 to $81.0079 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 this footnote.

F3 · ownership.nature: These shares are held by Atlas Venture Opportunity Fund II, L.P. ("Opportunity II"). The general partner of Opportunity II is Atlas Venture Associates Opportunity II, L.P. ("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.

SEC source: 0001591747-26-000002 · form4-09032026_090939.xml · nonDerivative · entry 7

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: Plan reported

Ownership: Indirect · See footnote

Disclosed balance after: 322,588

F1 · kind: Shares were sold pursuant to a Rule 10b5-1 trading plan adopted on July 30, 2026.

F6 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $80.9677 to $81.0079 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 this footnote.

F2 · ownership.nature: These shares are held by Atlas Venture Opportunity Fund I, L.P. ("Opportunity I"). The general partner of Opportunity I is Atlas Venture Associates Opportunity I, L.P. ("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.

SEC source: 0001591747-26-000002 · form4-09032026_090939.xml · nonDerivative · entry 6

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: Plan reported

Ownership: Indirect · See footnote

Disclosed balance after: 13,501

F1 · kind: Shares were sold pursuant to a Rule 10b5-1 trading plan adopted on July 30, 2026.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $79.95 to $80.9421 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 this footnote.

F4 · ownership.nature: 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.

SEC source: 0001591747-26-000002 · form4-09032026_090939.xml · nonDerivative · entry 5

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: Plan reported

Ownership: Indirect · See footnote

Disclosed balance after: 315,337

F1 · kind: Shares were sold pursuant to a Rule 10b5-1 trading plan adopted on July 30, 2026.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $79.95 to $80.9421 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 this footnote.

F3 · ownership.nature: These shares are held by Atlas Venture Opportunity Fund II, L.P. ("Opportunity II"). The general partner of Opportunity II is Atlas Venture Associates Opportunity II, L.P. ("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.

SEC source: 0001591747-26-000002 · form4-09032026_090939.xml · nonDerivative · entry 4

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: Plan reported

Ownership: Indirect · See footnote

Disclosed balance after: 322,598

F1 · kind: Shares were sold pursuant to a Rule 10b5-1 trading plan adopted on July 30, 2026.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $79.95 to $80.9421 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 this footnote.

F2 · ownership.nature: These shares are held by Atlas Venture Opportunity Fund I, L.P. ("Opportunity I"). The general partner of Opportunity I is Atlas Venture Associates Opportunity I, L.P. ("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.

SEC source: 0001591747-26-000002 · form4-09032026_090939.xml · nonDerivative · entry 3

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: Plan reported

Ownership: Indirect · See footnote

Disclosed balance after: 14,012

F1 · kind: Shares were sold pursuant to a Rule 10b5-1 trading plan adopted on July 30, 2026.

F4 · ownership.nature: 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.

SEC source: 0001591747-26-000002 · form4-09032026_090939.xml · nonDerivative · entry 2

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: Plan reported

Ownership: Indirect · See footnote

Disclosed balance after: 337,427

F1 · kind: Shares were sold pursuant to a Rule 10b5-1 trading plan adopted on July 30, 2026.

F3 · ownership.nature: These shares are held by Atlas Venture Opportunity Fund II, L.P. ("Opportunity II"). The general partner of Opportunity II is Atlas Venture Associates Opportunity II, L.P. ("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.

SEC source: 0001591747-26-000002 · form4-09032026_090939.xml · nonDerivative · entry 1

Bitterman Kevin · CIK 0001591747 · Director

10b5-1 filing: Plan reported

Ownership: Indirect · See footnote

Disclosed balance after: 349,140

F1 · kind: Shares were sold pursuant to a Rule 10b5-1 trading plan adopted on July 30, 2026.

F2 · ownership.nature: These shares are held by Atlas Venture Opportunity Fund I, L.P. ("Opportunity I"). The general partner of Opportunity I is Atlas Venture Associates Opportunity I, L.P. ("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.

SEC source: 0001193125-26-369179 · ownership.xml · derivative · entry 6

Yu Jonathan Yen-Wen · CIK 0001951849 · Chief Operating Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 13,847

Underlying: Common Stock · 8,796 shares

Expires 2032-12-28

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 17, 2026.

F4 · derivative.exercise_date: The shares underlying this option vest in 48 equal monthly installments following December 29, 2022, subject to the Reporting Person's continued service on each such vesting date.

SEC source: 0001193125-26-369179 · ownership.xml · nonDerivative · entry 4

Yu Jonathan Yen-Wen · CIK 0001951849 · Chief Operating Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 54,324

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 17, 2026.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $82.57 to $83.47, inclusive.

SEC source: 0001193125-26-369179 · ownership.xml · nonDerivative · entry 3

Yu Jonathan Yen-Wen · CIK 0001951849 · Chief Operating Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 63,120

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 17, 2026.

SEC source: 0001193125-26-369179 · ownership.xml · derivative · entry 5

Yu Jonathan Yen-Wen · CIK 0001951849 · Chief Operating Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 22,643

Underlying: Common Stock · 300 shares

Expires 2032-12-28

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 17, 2026.

F4 · derivative.exercise_date: The shares underlying this option vest in 48 equal monthly installments following December 29, 2022, subject to the Reporting Person's continued service on each such vesting date.

SEC source: 0001193125-26-369179 · ownership.xml · nonDerivative · entry 2

Yu Jonathan Yen-Wen · CIK 0001951849 · Chief Operating Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 54,324

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 17, 2026.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $82.50 to $82.60, 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 footnotes (2) and (3) to this Form 4.

SEC source: 0001193125-26-369179 · ownership.xml · nonDerivative · entry 1

Yu Jonathan Yen-Wen · CIK 0001951849 · Chief Operating Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 54,624

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 17, 2026.

SEC source: 0001193125-26-355841 · ownership.xml · derivative · entry 5

Quisel John D · CIK 0001586788 · Director · Chief Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 91,586

Underlying: Common Stock · 33,000 shares

Expires 2032-12-28

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 12, 2026.

F5 · derivative.exercise_date: The shares underlying this option vest in 48 equal monthly installments following December 29, 2022, subject to the Reporting Person's continued service on each such vesting date.

SEC source: 0001193125-26-355841 · ownership.xml · nonDerivative · entry 4

Quisel John D · CIK 0001586788 · Director · Chief Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 226,064

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 12, 2026.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $79.53 to $80.02, inclusive.

SEC source: 0001193125-26-355841 · ownership.xml · nonDerivative · entry 3

Quisel John D · CIK 0001586788 · Director · Chief Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 237,952

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 12, 2026.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $78.53 to $79.52, inclusive.

SEC source: 0001193125-26-355841 · ownership.xml · nonDerivative · entry 2

Quisel John D · CIK 0001586788 · Director · Chief Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 250,664

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 12, 2026.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $77.50 to $78.49, 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), (3) and (4) to this Form 4.

SEC source: 0001193125-26-355841 · ownership.xml · nonDerivative · entry 1

Quisel John D · CIK 0001586788 · Director · Chief Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 259,064

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 12, 2026.

SEC source: 0001193125-26-352823 · ownership.xml · derivative · entry 3

Yu Jonathan Yen-Wen · CIK 0001951849 · Chief Operating Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 22,943

Underlying: Common Stock · 804 shares

Expires 2032-12-28

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 17, 2026.

F3 · derivative.exercise_date: The shares underlying this option vest in 48 equal monthly installments following December 29, 2022, subject to the Reporting Person's continued service on each such vesting date.

SEC source: 0001193125-26-352823 · ownership.xml · nonDerivative · entry 2

Yu Jonathan Yen-Wen · CIK 0001951849 · Chief Operating Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 54,324

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 17, 2026.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $82.54 to $82.83, 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 this footnote (2) to this Form 4.

SEC source: 0001193125-26-352823 · ownership.xml · nonDerivative · entry 1

Yu Jonathan Yen-Wen · CIK 0001951849 · Chief Operating Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 55,128

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 17, 2026.

SEC source: 0001193125-26-340543 · ownership.xml · derivative · entry 3

Khara Rahul · CIK 0001951850 · Chief Legal Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 49,804

Underlying: Common Stock · 5,000 shares

Expires 2032-02-07

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: The transactions reported by the Reporting Person were effected pursuant to a Rule 10b5-1 trading plan adopted on March 19, 2026.

F3 · derivative.exercise_date: The shares underlying this option are fully vested and exercisable as of the date hereof.

SEC source: 0001193125-26-340543 · ownership.xml · nonDerivative · entry 2

Khara Rahul · CIK 0001951850 · Chief Legal Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 52,324

F1 · kind: The transactions reported by the Reporting Person were effected pursuant to a Rule 10b5-1 trading plan adopted on March 19, 2026.

F2 · balance_after: Includes 151 shares purchased pursuant to the Disc Medicine, Inc. Amended and Restated 2021 Employee Stock Purchase Plan on July 31, 2026.

SEC source: 0001193125-26-340543 · ownership.xml · nonDerivative · entry 1

Khara Rahul · CIK 0001951850 · Chief Legal Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 57,324

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: The transactions reported by the Reporting Person were effected pursuant to a Rule 10b5-1 trading plan adopted on March 19, 2026.

F2 · balance_after: Includes 151 shares purchased pursuant to the Disc Medicine, Inc. Amended and Restated 2021 Employee Stock Purchase Plan on July 31, 2026.

SEC source: 0001193125-26-303535 · ownership.xml · derivative · entry 7

Quisel John D · CIK 0001586788 · Director · Chief Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 124,586

Underlying: Common Stock · 7,416 shares

Expires 2032-12-28

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 12, 2026.

F6 · derivative.exercise_date: The shares underlying this option vest in 48 equal monthly installments following December 29, 2022, subject to the Reporting Person's continued service on each such vesting date.

SEC source: 0001193125-26-303535 · ownership.xml · derivative · entry 6

Quisel John D · CIK 0001586788 · Director · Chief Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 15,791

Underlying: Common Stock · 25,584 shares

Expires 2031-09-13

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 12, 2026.

F5 · derivative.exercise_date: The shares underlying this option are fully vested and exercisable as of the date hereof.

SEC source: 0001193125-26-303535 · ownership.xml · nonDerivative · entry 5

Quisel John D · CIK 0001586788 · Director · Chief Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 226,064

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 12, 2026.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $75.83 to $76.29, inclusive.

SEC source: 0001193125-26-303535 · ownership.xml · nonDerivative · entry 4

Quisel John D · CIK 0001586788 · Director · Chief Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 232,464

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 12, 2026.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $74.62 to $75.50, inclusive.

SEC source: 0001193125-26-303535 · ownership.xml · nonDerivative · entry 3

Quisel John D · CIK 0001586788 · Director · Chief Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 249,360

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 12, 2026.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $73.62 to $74.60, 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), (3) and (4) to this Form 4.

SEC source: 0001193125-26-303535 · ownership.xml · nonDerivative · entry 2

Quisel John D · CIK 0001586788 · Director · Chief Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 259,064

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 12, 2026.

SEC source: 0001193125-26-303535 · ownership.xml · nonDerivative · entry 1

Quisel John D · CIK 0001586788 · Director · Chief Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 251,648

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 12, 2026.

SEC source: 0001193125-26-299954 · ownership.xml · derivative · entry 3

Yu Jonathan Yen-Wen · CIK 0001951849 · Chief Operating Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 23,747

Underlying: Common Stock · 100 shares

Expires 2032-12-28

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 17, 2026.

F2 · derivative.exercise_date: The shares underlying this option vest in 48 equal monthly installments following December 29, 2022, subject to the Reporting Person's continued service on each such vesting date.

SEC source: 0001193125-26-299954 · ownership.xml · nonDerivative · entry 2

Yu Jonathan Yen-Wen · CIK 0001951849 · Chief Operating Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 54,324

F1 · kind: These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on March 17, 2026.