SION

SEC source: 0001415889-25-003504 · form4-02102025_100210.xml · nonDerivative · entry 3

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund, L.P. · CIK 0001780117 · Director

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnotes

Disclosed balance after: 2,222,084

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 · price: Each share of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock (collectively the "Preferred Stock") converted into shares of Common Stock of the Issuer on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering without payment of further consideration. The Preferred Stock had no expiration date.

F3 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund, RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus III Fund, L.P. (the "Nexus Fund III"), and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. The Adviser, the Adviser GP, the Fund, he Nexus Fund, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.

F5 · ownership.nature: Held directly by Nexus Fund III.

SEC source: 0001415889-25-003504 · form4-02102025_100210.xml · nonDerivative · entry 2

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund, L.P. · CIK 0001780117 · Director

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnotes

Disclosed balance after: 869,651

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 · price: Each share of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock (collectively the "Preferred Stock") converted into shares of Common Stock of the Issuer on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering without payment of further consideration. The Preferred Stock had no expiration date.

F3 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund, RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus III Fund, L.P. (the "Nexus Fund III"), and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. The Adviser, the Adviser GP, the Fund, he Nexus Fund, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.

F4 · ownership.nature: Held directly by the Nexus Fund.

SEC source: 0001415889-25-003504 · form4-02102025_100210.xml · nonDerivative · entry 1

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund, L.P. · CIK 0001780117 · Director

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnotes

Disclosed balance after: 5,900,779

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 · price: Each share of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock (collectively the "Preferred Stock") converted into shares of Common Stock of the Issuer on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering without payment of further consideration. The Preferred Stock had no expiration date.

F2 · ownership.nature: Held directly by RA Capital Healthcare Fund, L.P. (the "Fund").

F3 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund, RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus III Fund, L.P. (the "Nexus Fund III"), and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. The Adviser, the Adviser GP, the Fund, he Nexus Fund, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.

SEC source: 0000950170-25-017031 · ownership.xml · derivative · entry 4

Thompson Peter A. · CIK 0001357522 · Director

10b5-1 filing: No plan indicated

Ownership: Indirect · By OrbiMed Private Investments VIII, LP

Disclosed balance after: 0

Underlying: Common Stock · 1,402,204 shares

Expires not disclosed

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_price: Each share of Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.exercise_date: Each share of Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.expiration_date: Each share of Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F2 · ownership.nature: The securities are held of record by OrbiMed Private Investments VIII, LP ("OPI VIII"). OrbiMed Capital GP VIII LLC ("GP VIII") is the general partner of OPI VIII and OrbiMed Advisors LLC ("OrbiMed Advisors") is the managing member of GP VIII. By virtue of such relationships, GP VIII and OrbiMed Advisors may be deemed to have voting and investment power with respect to the shares held by OPI VIII and as a result may be deemed to have beneficial ownership of such shares. OrbiMed Advisors exercises investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by OPI VIII.

F3 · ownership.nature: Each of OrbiMed Advisors, GP VIII and the Reporting Person disclaims beneficial ownership of the securities reported herein for purposes of Rule 16(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its or his pecuniary interest therein, if any. This report shall not be deemed an admission that any such entity or person is a beneficial owner of such securities for purpose of Section 16 of the Exchange Act, or for any other purpose.

SEC source: 0000950170-25-017031 · ownership.xml · derivative · entry 3

Thompson Peter A. · CIK 0001357522 · Director

10b5-1 filing: No plan indicated

Ownership: Indirect · By OrbiMed Private Investments VIII, LP

Disclosed balance after: 0

Underlying: Common Stock · 1,752,755 shares

Expires not disclosed

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_price: Each share of Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.exercise_date: Each share of Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.expiration_date: Each share of Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F2 · ownership.nature: The securities are held of record by OrbiMed Private Investments VIII, LP ("OPI VIII"). OrbiMed Capital GP VIII LLC ("GP VIII") is the general partner of OPI VIII and OrbiMed Advisors LLC ("OrbiMed Advisors") is the managing member of GP VIII. By virtue of such relationships, GP VIII and OrbiMed Advisors may be deemed to have voting and investment power with respect to the shares held by OPI VIII and as a result may be deemed to have beneficial ownership of such shares. OrbiMed Advisors exercises investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by OPI VIII.

F3 · ownership.nature: Each of OrbiMed Advisors, GP VIII and the Reporting Person disclaims beneficial ownership of the securities reported herein for purposes of Rule 16(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its or his pecuniary interest therein, if any. This report shall not be deemed an admission that any such entity or person is a beneficial owner of such securities for purpose of Section 16 of the Exchange Act, or for any other purpose.

SEC source: 0000950170-25-017031 · ownership.xml · nonDerivative · entry 2

Thompson Peter A. · CIK 0001357522 · Director

10b5-1 filing: No plan indicated

Ownership: Indirect · By OrbiMed Private Investments VIII, LP

Disclosed balance after: 3,704,959

F4 · shares: Reflects shares purchased in the Issuer's initial public offering.

F2 · ownership.nature: The securities are held of record by OrbiMed Private Investments VIII, LP ("OPI VIII"). OrbiMed Capital GP VIII LLC ("GP VIII") is the general partner of OPI VIII and OrbiMed Advisors LLC ("OrbiMed Advisors") is the managing member of GP VIII. By virtue of such relationships, GP VIII and OrbiMed Advisors may be deemed to have voting and investment power with respect to the shares held by OPI VIII and as a result may be deemed to have beneficial ownership of such shares. OrbiMed Advisors exercises investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by OPI VIII.

F3 · ownership.nature: Each of OrbiMed Advisors, GP VIII and the Reporting Person disclaims beneficial ownership of the securities reported herein for purposes of Rule 16(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its or his pecuniary interest therein, if any. This report shall not be deemed an admission that any such entity or person is a beneficial owner of such securities for purpose of Section 16 of the Exchange Act, or for any other purpose.

SEC source: 0000950170-25-017031 · ownership.xml · nonDerivative · entry 1

Thompson Peter A. · CIK 0001357522 · Director

10b5-1 filing: No plan indicated

Ownership: Indirect · By OrbiMed Private Investments VIII, LP

Disclosed balance after: 3,154,959

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 · price: Each share of Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F2 · ownership.nature: The securities are held of record by OrbiMed Private Investments VIII, LP ("OPI VIII"). OrbiMed Capital GP VIII LLC ("GP VIII") is the general partner of OPI VIII and OrbiMed Advisors LLC ("OrbiMed Advisors") is the managing member of GP VIII. By virtue of such relationships, GP VIII and OrbiMed Advisors may be deemed to have voting and investment power with respect to the shares held by OPI VIII and as a result may be deemed to have beneficial ownership of such shares. OrbiMed Advisors exercises investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by OPI VIII.

F3 · ownership.nature: Each of OrbiMed Advisors, GP VIII and the Reporting Person disclaims beneficial ownership of the securities reported herein for purposes of Rule 16(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its or his pecuniary interest therein, if any. This report shall not be deemed an admission that any such entity or person is a beneficial owner of such securities for purpose of Section 16 of the Exchange Act, or for any other purpose.

SEC source: 0000950170-25-017029 · ownership.xml · derivative · entry 8

Booth Bruce · CIK 0001451612 · Director

10b5-1 filing: No plan indicated

Ownership: Indirect · By Atlas Venture Opportunity Fund II, L.P.

Disclosed balance after: 0

Underlying: Common Stock · 747,727 shares

Expires not disclosed

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_price: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.exercise_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.expiration_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F3 · ownership.nature: These shares are held directly by Atlas Venture Opportunity Fund II, L.P. ("AVOF II"). The general partner of AVOF II is Atlas Venture Associates Opportunity II, L.P. ("AVAO II LP"). Atlas Venture Associates Opportunity II, LLC ("AVAO II LLC") is the general partner of AVAO II LP. The Reporting Person is a member of AVAO II LLC and disclaims beneficial ownership of such securities held by AVOF II, except to the extent of his pecuniary interest therein, if any.

SEC source: 0000950170-25-017029 · ownership.xml · derivative · entry 7

Booth Bruce · CIK 0001451612 · Director

10b5-1 filing: No plan indicated

Ownership: Indirect · By Atlas Venture Fund XI, L.P.

Disclosed balance after: 0

Underlying: Common Stock · 42,068 shares

Expires not disclosed

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_price: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.exercise_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.expiration_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F2 · ownership.nature: These shares are held directly by Atlas Venture Fund XI, L.P. ("AVF XI "). The general partner of AVF XI is Atlas Venture Associates XI, L.P. ("AVA XI LP"). Atlas Venture Associates XI, LLC ("AVA XI LLC") is the general partner of AVA XI LP. The Reporting Person is a member of AVA XI LLC and disclaims beneficial ownership of such securities held by AVF XI, except to the extent of his pecuniary interest therein, if any.

SEC source: 0000950170-25-017029 · ownership.xml · derivative · entry 6

Booth Bruce · CIK 0001451612 · Director

10b5-1 filing: No plan indicated

Ownership: Indirect · By Atlas Venture Fund XI, L.P.

Disclosed balance after: 0

Underlying: Common Stock · 888,599 shares

Expires not disclosed

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_price: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.exercise_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.expiration_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F2 · ownership.nature: These shares are held directly by Atlas Venture Fund XI, L.P. ("AVF XI "). The general partner of AVF XI is Atlas Venture Associates XI, L.P. ("AVA XI LP"). Atlas Venture Associates XI, LLC ("AVA XI LLC") is the general partner of AVA XI LP. The Reporting Person is a member of AVA XI LLC and disclaims beneficial ownership of such securities held by AVF XI, except to the extent of his pecuniary interest therein, if any.

SEC source: 0000950170-25-017029 · ownership.xml · derivative · entry 5

Booth Bruce · CIK 0001451612 · Director

10b5-1 filing: No plan indicated

Ownership: Indirect · By Atlas Venture Fund XI, L.P.

Disclosed balance after: 0

Underlying: Common Stock · 1,236,271 shares

Expires not disclosed

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_price: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.exercise_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.expiration_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F2 · ownership.nature: These shares are held directly by Atlas Venture Fund XI, L.P. ("AVF XI "). The general partner of AVF XI is Atlas Venture Associates XI, L.P. ("AVA XI LP"). Atlas Venture Associates XI, LLC ("AVA XI LLC") is the general partner of AVA XI LP. The Reporting Person is a member of AVA XI LLC and disclaims beneficial ownership of such securities held by AVF XI, except to the extent of his pecuniary interest therein, if any.

SEC source: 0000950170-25-017029 · ownership.xml · derivative · entry 4

Booth Bruce · CIK 0001451612 · Director

10b5-1 filing: No plan indicated

Ownership: Indirect · By Atlas Venture Fund XI, L.P.

Disclosed balance after: 0

Underlying: Common Stock · 719,355 shares

Expires not disclosed

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_price: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.exercise_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.expiration_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F2 · ownership.nature: These shares are held directly by Atlas Venture Fund XI, L.P. ("AVF XI "). The general partner of AVF XI is Atlas Venture Associates XI, L.P. ("AVA XI LP"). Atlas Venture Associates XI, LLC ("AVA XI LLC") is the general partner of AVA XI LP. The Reporting Person is a member of AVA XI LLC and disclaims beneficial ownership of such securities held by AVF XI, except to the extent of his pecuniary interest therein, if any.

SEC source: 0000950170-25-017029 · ownership.xml · nonDerivative · entry 3

Booth Bruce · CIK 0001451612 · Director

10b5-1 filing: No plan indicated

Ownership: Indirect · By Atlas Venture Opportunity Fund II, L.P.

Disclosed balance after: 807,727

F3 · ownership.nature: These shares are held directly by Atlas Venture Opportunity Fund II, L.P. ("AVOF II"). The general partner of AVOF II is Atlas Venture Associates Opportunity II, L.P. ("AVAO II LP"). Atlas Venture Associates Opportunity II, LLC ("AVAO II LLC") is the general partner of AVAO II LP. The Reporting Person is a member of AVAO II LLC and disclaims beneficial ownership of such securities held by AVOF II, except to the extent of his pecuniary interest therein, if any.

SEC source: 0000950170-25-017029 · ownership.xml · nonDerivative · entry 2

Booth Bruce · CIK 0001451612 · Director

10b5-1 filing: No plan indicated

Ownership: Indirect · By Atlas Venture Opportunity Fund II, L.P.

Disclosed balance after: 747,727

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 · price: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F3 · ownership.nature: These shares are held directly by Atlas Venture Opportunity Fund II, L.P. ("AVOF II"). The general partner of AVOF II is Atlas Venture Associates Opportunity II, L.P. ("AVAO II LP"). Atlas Venture Associates Opportunity II, LLC ("AVAO II LLC") is the general partner of AVAO II LP. The Reporting Person is a member of AVAO II LLC and disclaims beneficial ownership of such securities held by AVOF II, except to the extent of his pecuniary interest therein, if any.

SEC source: 0000950170-25-017029 · ownership.xml · nonDerivative · entry 1

Booth Bruce · CIK 0001451612 · Director

10b5-1 filing: No plan indicated

Ownership: Indirect · By Atlas Venture Fund XI, L.P.

Disclosed balance after: 2,886,293

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 · price: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F2 · ownership.nature: These shares are held directly by Atlas Venture Fund XI, L.P. ("AVF XI "). The general partner of AVF XI is Atlas Venture Associates XI, L.P. ("AVA XI LP"). Atlas Venture Associates XI, LLC ("AVA XI LLC") is the general partner of AVA XI LP. The Reporting Person is a member of AVA XI LLC and disclaims beneficial ownership of such securities held by AVF XI, except to the extent of his pecuniary interest therein, if any.

SEC source: 0000950170-25-017030 · ownership.xml · derivative · entry 8

Atlas Venture Fund XI, L.P. · CIK 0001708269 · 10% owner

Atlas Venture Associates XI, L.P. · CIK 0001780068 · 10% owner

Atlas Venture Associates XI, LLC · CIK 0001780067 · 10% owner

Atlas Venture Opportunity Fund II, L.P. · CIK 0001885327 · 10% owner

Atlas Venture Associates Opportunity II, LP · CIK 0001935814 · 10% owner

Atlas Venture Associates Opportunity II, LLC · CIK 0001935810 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · By Atlas Venture Opportunity Fund II, L.P.

Disclosed balance after: 0

Underlying: Common Stock · 747,727 shares

Expires not disclosed

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_price: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.exercise_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.expiration_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F3 · ownership.nature: These shares are held directly by Atlas Venture Opportunity Fund II, L.P. ("AVOF II"). The general partner of AVOF II is Atlas Venture Associates Opportunity II, L.P. ("AVAO II LP"). Atlas Venture Associates Opportunity II, LLC ("AVAO II LLC") is the general partner of AVAO II LP. Each of AVAO II LP and AVAO II LLC disclaims Section 16 beneficial ownership of the securities held by AVOF II, except to the extent of its pecuniary interest therein, if any.

SEC source: 0000950170-25-017030 · ownership.xml · derivative · entry 7

Atlas Venture Fund XI, L.P. · CIK 0001708269 · 10% owner

Atlas Venture Associates XI, L.P. · CIK 0001780068 · 10% owner

Atlas Venture Associates XI, LLC · CIK 0001780067 · 10% owner

Atlas Venture Opportunity Fund II, L.P. · CIK 0001885327 · 10% owner

Atlas Venture Associates Opportunity II, LP · CIK 0001935814 · 10% owner

Atlas Venture Associates Opportunity II, LLC · CIK 0001935810 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 42,068 shares

Expires not disclosed

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_price: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.exercise_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.expiration_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F2 · ownership.direct: These shares are held directly by Atlas Venture Fund XI, L.P. ("AVF XI"). The general partner of AVF XI is Atlas Venture Associates XI, L.P. ("AVA XI LP"). Atlas Venture Associates XI, LLC ("AVA XI LLC") is the general partner of AVA XI LP. Each of AVA XI LP and AVA XI LLC disclaims Section 16 beneficial ownership of the securities held by AVF XI, except to the extent of its pecuniary interest therein, if any.

SEC source: 0000950170-25-017030 · ownership.xml · derivative · entry 6

Atlas Venture Fund XI, L.P. · CIK 0001708269 · 10% owner

Atlas Venture Associates XI, L.P. · CIK 0001780068 · 10% owner

Atlas Venture Associates XI, LLC · CIK 0001780067 · 10% owner

Atlas Venture Opportunity Fund II, L.P. · CIK 0001885327 · 10% owner

Atlas Venture Associates Opportunity II, LP · CIK 0001935814 · 10% owner

Atlas Venture Associates Opportunity II, LLC · CIK 0001935810 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 888,599 shares

Expires not disclosed

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_price: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.exercise_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.expiration_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F2 · ownership.direct: These shares are held directly by Atlas Venture Fund XI, L.P. ("AVF XI"). The general partner of AVF XI is Atlas Venture Associates XI, L.P. ("AVA XI LP"). Atlas Venture Associates XI, LLC ("AVA XI LLC") is the general partner of AVA XI LP. Each of AVA XI LP and AVA XI LLC disclaims Section 16 beneficial ownership of the securities held by AVF XI, except to the extent of its pecuniary interest therein, if any.

SEC source: 0000950170-25-017030 · ownership.xml · derivative · entry 5

Atlas Venture Fund XI, L.P. · CIK 0001708269 · 10% owner

Atlas Venture Associates XI, L.P. · CIK 0001780068 · 10% owner

Atlas Venture Associates XI, LLC · CIK 0001780067 · 10% owner

Atlas Venture Opportunity Fund II, L.P. · CIK 0001885327 · 10% owner

Atlas Venture Associates Opportunity II, LP · CIK 0001935814 · 10% owner

Atlas Venture Associates Opportunity II, LLC · CIK 0001935810 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 1,236,271 shares

Expires not disclosed

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_price: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.exercise_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.expiration_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F2 · ownership.direct: These shares are held directly by Atlas Venture Fund XI, L.P. ("AVF XI"). The general partner of AVF XI is Atlas Venture Associates XI, L.P. ("AVA XI LP"). Atlas Venture Associates XI, LLC ("AVA XI LLC") is the general partner of AVA XI LP. Each of AVA XI LP and AVA XI LLC disclaims Section 16 beneficial ownership of the securities held by AVF XI, except to the extent of its pecuniary interest therein, if any.

SEC source: 0000950170-25-017030 · ownership.xml · derivative · entry 4

Atlas Venture Fund XI, L.P. · CIK 0001708269 · 10% owner

Atlas Venture Associates XI, L.P. · CIK 0001780068 · 10% owner

Atlas Venture Associates XI, LLC · CIK 0001780067 · 10% owner

Atlas Venture Opportunity Fund II, L.P. · CIK 0001885327 · 10% owner

Atlas Venture Associates Opportunity II, LP · CIK 0001935814 · 10% owner

Atlas Venture Associates Opportunity II, LLC · CIK 0001935810 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 719,355 shares

Expires not disclosed

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_price: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.exercise_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F1 · derivative.expiration_date: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F2 · ownership.direct: These shares are held directly by Atlas Venture Fund XI, L.P. ("AVF XI"). The general partner of AVF XI is Atlas Venture Associates XI, L.P. ("AVA XI LP"). Atlas Venture Associates XI, LLC ("AVA XI LLC") is the general partner of AVA XI LP. Each of AVA XI LP and AVA XI LLC disclaims Section 16 beneficial ownership of the securities held by AVF XI, except to the extent of its pecuniary interest therein, if any.

SEC source: 0000950170-25-017030 · ownership.xml · nonDerivative · entry 3

Atlas Venture Fund XI, L.P. · CIK 0001708269 · 10% owner

Atlas Venture Associates XI, L.P. · CIK 0001780068 · 10% owner

Atlas Venture Associates XI, LLC · CIK 0001780067 · 10% owner

Atlas Venture Opportunity Fund II, L.P. · CIK 0001885327 · 10% owner

Atlas Venture Associates Opportunity II, LP · CIK 0001935814 · 10% owner

Atlas Venture Associates Opportunity II, LLC · CIK 0001935810 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · By Atlas Venture Opportunity Fund II, L.P.

Disclosed balance after: 807,727

F3 · ownership.nature: These shares are held directly by Atlas Venture Opportunity Fund II, L.P. ("AVOF II"). The general partner of AVOF II is Atlas Venture Associates Opportunity II, L.P. ("AVAO II LP"). Atlas Venture Associates Opportunity II, LLC ("AVAO II LLC") is the general partner of AVAO II LP. Each of AVAO II LP and AVAO II LLC disclaims Section 16 beneficial ownership of the securities held by AVOF II, except to the extent of its pecuniary interest therein, if any.

SEC source: 0000950170-25-017030 · ownership.xml · nonDerivative · entry 2

Atlas Venture Fund XI, L.P. · CIK 0001708269 · 10% owner

Atlas Venture Associates XI, L.P. · CIK 0001780068 · 10% owner

Atlas Venture Associates XI, LLC · CIK 0001780067 · 10% owner

Atlas Venture Opportunity Fund II, L.P. · CIK 0001885327 · 10% owner

Atlas Venture Associates Opportunity II, LP · CIK 0001935814 · 10% owner

Atlas Venture Associates Opportunity II, LLC · CIK 0001935810 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · By Atlas Venture Opportunity Fund II, L.P.

Disclosed balance after: 747,727

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 · price: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F3 · ownership.nature: These shares are held directly by Atlas Venture Opportunity Fund II, L.P. ("AVOF II"). The general partner of AVOF II is Atlas Venture Associates Opportunity II, L.P. ("AVAO II LP"). Atlas Venture Associates Opportunity II, LLC ("AVAO II LLC") is the general partner of AVAO II LP. Each of AVAO II LP and AVAO II LLC disclaims Section 16 beneficial ownership of the securities held by AVOF II, except to the extent of its pecuniary interest therein, if any.

SEC source: 0000950170-25-017030 · ownership.xml · nonDerivative · entry 1

Atlas Venture Fund XI, L.P. · CIK 0001708269 · 10% owner

Atlas Venture Associates XI, L.P. · CIK 0001780068 · 10% owner

Atlas Venture Associates XI, LLC · CIK 0001780067 · 10% owner

Atlas Venture Opportunity Fund II, L.P. · CIK 0001885327 · 10% owner

Atlas Venture Associates Opportunity II, LP · CIK 0001935814 · 10% owner

Atlas Venture Associates Opportunity II, LLC · CIK 0001935810 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 2,886,293

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 · price: Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering on February 10, 2025. The Preferred Stock had no expiration date.

F2 · ownership.direct: These shares are held directly by Atlas Venture Fund XI, L.P. ("AVF XI"). The general partner of AVF XI is Atlas Venture Associates XI, L.P. ("AVA XI LP"). Atlas Venture Associates XI, LLC ("AVA XI LLC") is the general partner of AVA XI LP. Each of AVA XI LP and AVA XI LLC disclaims Section 16 beneficial ownership of the securities held by AVF XI, except to the extent of its pecuniary interest therein, if any.

SEC source: 0001999371-25-001562 · tpg-form4.xml · derivative · entry 6

TPG GP A, LLC · CIK 0001903793 · 10% owner

COULTER JAMES G · CIK 0001099776 · 10% owner

WINKELRIED JON · CIK 0001366946 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See Explanation of Responses

Disclosed balance after: 0

Underlying: Common Stock · 1,208,364 shares

Expires not disclosed

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.

F3 · derivative.exercise_price: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F3 · price: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F3 · derivative.exercise_date: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F3 · derivative.expiration_date: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F1 · ownership.nature: Each of James G. Coulter and Jon Winkelried own entities that control TPG GP A, LLC (together with Messrs. Coulter and Winkelried, the "Reporting Persons"), which is the managing member of each of (i) TPG Group Holdings (SBS) Advisors, LLC, which is the general partner of TPG Group Holdings (SBS), L.P., and (ii) Alabama Investments (Parallel) GP, LLC, which is the general partner of each of (a) Alabama Investments (Parallel), LP, (b) Alabama Investments (Parallel) Founder A, LP and (c) Alabama Investments (Parallel) Founder G, LP, which, collectively with TPG Group Holdings (SBS), L.P., Alabama Investments (Parallel), LP and Alabama Investments (Parallel) Founder A, LP, holds 100% of the shares of Class B common stock (which represents a majority of the combined voting power of the common stock) of TPG Inc.

F2 · ownership.nature: TPG Inc. is the sole member of TPG GPCo, LLC, which is the sole member of TPG Holdings II-A, LLC, which is the general partner of TPG Operating Group II, L.P., which is the sole member of TPG Holdings I-A, LLC, which is the general partner of TPG Operating Group I, L.P., which is the sole member of The Rise Fund GenPar Advisors, LLC, which is the general partner of The Rise Fund GenPar, L.P., which is the managing member of The Rise Fund SPV GP, LLC, which is the general partner of each of The Rise Fund Sling, L.P., which directly holds 5,476,598 shares of Common Stock ("Common Stock") of Sionna Therapeutics, Inc. (the "Issuer"), and The Rise Fund Sling II, L.P. (together with The Rise Fund Sling, L.P., the "TPG Funds"), which directly holds 1,208,364 shares of Common Stock.

F3 · ownership.nature: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F5 · ownership.nature: Because of the relationship between the Reporting Persons and the TPG Funds, the Reporting Persons may be deemed to beneficially own the securities reported herein to the extent of the greater of their respective direct or indirect pecuniary interests in the profits or capital accounts of the TPG Funds. Each of the TPG Funds and each Reporting Person disclaims beneficial ownership of the securities reported herein, except to the extent of such TPG Fund's or such Reporting Person's pecuniary interest therein, if any.

F6 · ownership.nature: Pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), this filing shall not be deemed an admission that the Reporting Persons are, for purposes of Section 16 of the Exchange Act or otherwise, the beneficial owners of any equity securities in excess of their respective pecuniary interests.

SEC source: 0001999371-25-001562 · tpg-form4.xml · derivative · entry 5

TPG GP A, LLC · CIK 0001903793 · 10% owner

COULTER JAMES G · CIK 0001099776 · 10% owner

WINKELRIED JON · CIK 0001366946 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See Explanation of Responses

Disclosed balance after: 0

Underlying: Common Stock · 1,557,408 shares

Expires not disclosed

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.

F3 · derivative.exercise_price: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F3 · price: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F3 · derivative.exercise_date: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F3 · derivative.expiration_date: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F1 · ownership.nature: Each of James G. Coulter and Jon Winkelried own entities that control TPG GP A, LLC (together with Messrs. Coulter and Winkelried, the "Reporting Persons"), which is the managing member of each of (i) TPG Group Holdings (SBS) Advisors, LLC, which is the general partner of TPG Group Holdings (SBS), L.P., and (ii) Alabama Investments (Parallel) GP, LLC, which is the general partner of each of (a) Alabama Investments (Parallel), LP, (b) Alabama Investments (Parallel) Founder A, LP and (c) Alabama Investments (Parallel) Founder G, LP, which, collectively with TPG Group Holdings (SBS), L.P., Alabama Investments (Parallel), LP and Alabama Investments (Parallel) Founder A, LP, holds 100% of the shares of Class B common stock (which represents a majority of the combined voting power of the common stock) of TPG Inc.

F2 · ownership.nature: TPG Inc. is the sole member of TPG GPCo, LLC, which is the sole member of TPG Holdings II-A, LLC, which is the general partner of TPG Operating Group II, L.P., which is the sole member of TPG Holdings I-A, LLC, which is the general partner of TPG Operating Group I, L.P., which is the sole member of The Rise Fund GenPar Advisors, LLC, which is the general partner of The Rise Fund GenPar, L.P., which is the managing member of The Rise Fund SPV GP, LLC, which is the general partner of each of The Rise Fund Sling, L.P., which directly holds 5,476,598 shares of Common Stock ("Common Stock") of Sionna Therapeutics, Inc. (the "Issuer"), and The Rise Fund Sling II, L.P. (together with The Rise Fund Sling, L.P., the "TPG Funds"), which directly holds 1,208,364 shares of Common Stock.

F3 · ownership.nature: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F5 · ownership.nature: Because of the relationship between the Reporting Persons and the TPG Funds, the Reporting Persons may be deemed to beneficially own the securities reported herein to the extent of the greater of their respective direct or indirect pecuniary interests in the profits or capital accounts of the TPG Funds. Each of the TPG Funds and each Reporting Person disclaims beneficial ownership of the securities reported herein, except to the extent of such TPG Fund's or such Reporting Person's pecuniary interest therein, if any.

F6 · ownership.nature: Pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), this filing shall not be deemed an admission that the Reporting Persons are, for purposes of Section 16 of the Exchange Act or otherwise, the beneficial owners of any equity securities in excess of their respective pecuniary interests.

SEC source: 0001999371-25-001562 · tpg-form4.xml · derivative · entry 4

TPG GP A, LLC · CIK 0001903793 · 10% owner

COULTER JAMES G · CIK 0001099776 · 10% owner

WINKELRIED JON · CIK 0001366946 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See Explanation of Responses

Disclosed balance after: 0

Underlying: Common Stock · 1,236,272 shares

Expires not disclosed

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.

F3 · derivative.exercise_price: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F3 · price: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F3 · derivative.exercise_date: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F3 · derivative.expiration_date: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F1 · ownership.nature: Each of James G. Coulter and Jon Winkelried own entities that control TPG GP A, LLC (together with Messrs. Coulter and Winkelried, the "Reporting Persons"), which is the managing member of each of (i) TPG Group Holdings (SBS) Advisors, LLC, which is the general partner of TPG Group Holdings (SBS), L.P., and (ii) Alabama Investments (Parallel) GP, LLC, which is the general partner of each of (a) Alabama Investments (Parallel), LP, (b) Alabama Investments (Parallel) Founder A, LP and (c) Alabama Investments (Parallel) Founder G, LP, which, collectively with TPG Group Holdings (SBS), L.P., Alabama Investments (Parallel), LP and Alabama Investments (Parallel) Founder A, LP, holds 100% of the shares of Class B common stock (which represents a majority of the combined voting power of the common stock) of TPG Inc.

F2 · ownership.nature: TPG Inc. is the sole member of TPG GPCo, LLC, which is the sole member of TPG Holdings II-A, LLC, which is the general partner of TPG Operating Group II, L.P., which is the sole member of TPG Holdings I-A, LLC, which is the general partner of TPG Operating Group I, L.P., which is the sole member of The Rise Fund GenPar Advisors, LLC, which is the general partner of The Rise Fund GenPar, L.P., which is the managing member of The Rise Fund SPV GP, LLC, which is the general partner of each of The Rise Fund Sling, L.P., which directly holds 5,476,598 shares of Common Stock ("Common Stock") of Sionna Therapeutics, Inc. (the "Issuer"), and The Rise Fund Sling II, L.P. (together with The Rise Fund Sling, L.P., the "TPG Funds"), which directly holds 1,208,364 shares of Common Stock.

F3 · ownership.nature: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F5 · ownership.nature: Because of the relationship between the Reporting Persons and the TPG Funds, the Reporting Persons may be deemed to beneficially own the securities reported herein to the extent of the greater of their respective direct or indirect pecuniary interests in the profits or capital accounts of the TPG Funds. Each of the TPG Funds and each Reporting Person disclaims beneficial ownership of the securities reported herein, except to the extent of such TPG Fund's or such Reporting Person's pecuniary interest therein, if any.

F6 · ownership.nature: Pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), this filing shall not be deemed an admission that the Reporting Persons are, for purposes of Section 16 of the Exchange Act or otherwise, the beneficial owners of any equity securities in excess of their respective pecuniary interests.

SEC source: 0001999371-25-001562 · tpg-form4.xml · derivative · entry 3

TPG GP A, LLC · CIK 0001903793 · 10% owner

COULTER JAMES G · CIK 0001099776 · 10% owner

WINKELRIED JON · CIK 0001366946 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See Explanation of Responses

Disclosed balance after: 0

Underlying: Common Stock · 873,503 shares

Expires not disclosed

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.

F3 · derivative.exercise_price: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F3 · price: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F3 · derivative.exercise_date: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F3 · derivative.expiration_date: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F1 · ownership.nature: Each of James G. Coulter and Jon Winkelried own entities that control TPG GP A, LLC (together with Messrs. Coulter and Winkelried, the "Reporting Persons"), which is the managing member of each of (i) TPG Group Holdings (SBS) Advisors, LLC, which is the general partner of TPG Group Holdings (SBS), L.P., and (ii) Alabama Investments (Parallel) GP, LLC, which is the general partner of each of (a) Alabama Investments (Parallel), LP, (b) Alabama Investments (Parallel) Founder A, LP and (c) Alabama Investments (Parallel) Founder G, LP, which, collectively with TPG Group Holdings (SBS), L.P., Alabama Investments (Parallel), LP and Alabama Investments (Parallel) Founder A, LP, holds 100% of the shares of Class B common stock (which represents a majority of the combined voting power of the common stock) of TPG Inc.

F2 · ownership.nature: TPG Inc. is the sole member of TPG GPCo, LLC, which is the sole member of TPG Holdings II-A, LLC, which is the general partner of TPG Operating Group II, L.P., which is the sole member of TPG Holdings I-A, LLC, which is the general partner of TPG Operating Group I, L.P., which is the sole member of The Rise Fund GenPar Advisors, LLC, which is the general partner of The Rise Fund GenPar, L.P., which is the managing member of The Rise Fund SPV GP, LLC, which is the general partner of each of The Rise Fund Sling, L.P., which directly holds 5,476,598 shares of Common Stock ("Common Stock") of Sionna Therapeutics, Inc. (the "Issuer"), and The Rise Fund Sling II, L.P. (together with The Rise Fund Sling, L.P., the "TPG Funds"), which directly holds 1,208,364 shares of Common Stock.

F3 · ownership.nature: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F5 · ownership.nature: Because of the relationship between the Reporting Persons and the TPG Funds, the Reporting Persons may be deemed to beneficially own the securities reported herein to the extent of the greater of their respective direct or indirect pecuniary interests in the profits or capital accounts of the TPG Funds. Each of the TPG Funds and each Reporting Person disclaims beneficial ownership of the securities reported herein, except to the extent of such TPG Fund's or such Reporting Person's pecuniary interest therein, if any.

F6 · ownership.nature: Pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), this filing shall not be deemed an admission that the Reporting Persons are, for purposes of Section 16 of the Exchange Act or otherwise, the beneficial owners of any equity securities in excess of their respective pecuniary interests.

SEC source: 0001999371-25-001562 · tpg-form4.xml · nonDerivative · entry 2

TPG GP A, LLC · CIK 0001903793 · 10% owner

COULTER JAMES G · CIK 0001099776 · 10% owner

WINKELRIED JON · CIK 0001366946 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See Explanation of Responses

Disclosed balance after: 6,684,962

F4 · kind: On February 10, 2025, in connection with the Issuer's initial public offering, The Rise Fund Sling, L.P. acquired an aggregate of 1,125,000 shares of Common Stock at a price of $18.00 per share.

F1 · ownership.nature: Each of James G. Coulter and Jon Winkelried own entities that control TPG GP A, LLC (together with Messrs. Coulter and Winkelried, the "Reporting Persons"), which is the managing member of each of (i) TPG Group Holdings (SBS) Advisors, LLC, which is the general partner of TPG Group Holdings (SBS), L.P., and (ii) Alabama Investments (Parallel) GP, LLC, which is the general partner of each of (a) Alabama Investments (Parallel), LP, (b) Alabama Investments (Parallel) Founder A, LP and (c) Alabama Investments (Parallel) Founder G, LP, which, collectively with TPG Group Holdings (SBS), L.P., Alabama Investments (Parallel), LP and Alabama Investments (Parallel) Founder A, LP, holds 100% of the shares of Class B common stock (which represents a majority of the combined voting power of the common stock) of TPG Inc.

F2 · ownership.nature: TPG Inc. is the sole member of TPG GPCo, LLC, which is the sole member of TPG Holdings II-A, LLC, which is the general partner of TPG Operating Group II, L.P., which is the sole member of TPG Holdings I-A, LLC, which is the general partner of TPG Operating Group I, L.P., which is the sole member of The Rise Fund GenPar Advisors, LLC, which is the general partner of The Rise Fund GenPar, L.P., which is the managing member of The Rise Fund SPV GP, LLC, which is the general partner of each of The Rise Fund Sling, L.P., which directly holds 5,476,598 shares of Common Stock ("Common Stock") of Sionna Therapeutics, Inc. (the "Issuer"), and The Rise Fund Sling II, L.P. (together with The Rise Fund Sling, L.P., the "TPG Funds"), which directly holds 1,208,364 shares of Common Stock.

F4 · ownership.nature: On February 10, 2025, in connection with the Issuer's initial public offering, The Rise Fund Sling, L.P. acquired an aggregate of 1,125,000 shares of Common Stock at a price of $18.00 per share.

F5 · ownership.nature: Because of the relationship between the Reporting Persons and the TPG Funds, the Reporting Persons may be deemed to beneficially own the securities reported herein to the extent of the greater of their respective direct or indirect pecuniary interests in the profits or capital accounts of the TPG Funds. Each of the TPG Funds and each Reporting Person disclaims beneficial ownership of the securities reported herein, except to the extent of such TPG Fund's or such Reporting Person's pecuniary interest therein, if any.

F6 · ownership.nature: Pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), this filing shall not be deemed an admission that the Reporting Persons are, for purposes of Section 16 of the Exchange Act or otherwise, the beneficial owners of any equity securities in excess of their respective pecuniary interests.

SEC source: 0001999371-25-001562 · tpg-form4.xml · nonDerivative · entry 1

TPG GP A, LLC · CIK 0001903793 · 10% owner

COULTER JAMES G · CIK 0001099776 · 10% owner

WINKELRIED JON · CIK 0001366946 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See Explanation of Responses

Disclosed balance after: 5,559,962

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.

F3 · price: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F1 · ownership.nature: Each of James G. Coulter and Jon Winkelried own entities that control TPG GP A, LLC (together with Messrs. Coulter and Winkelried, the "Reporting Persons"), which is the managing member of each of (i) TPG Group Holdings (SBS) Advisors, LLC, which is the general partner of TPG Group Holdings (SBS), L.P., and (ii) Alabama Investments (Parallel) GP, LLC, which is the general partner of each of (a) Alabama Investments (Parallel), LP, (b) Alabama Investments (Parallel) Founder A, LP and (c) Alabama Investments (Parallel) Founder G, LP, which, collectively with TPG Group Holdings (SBS), L.P., Alabama Investments (Parallel), LP and Alabama Investments (Parallel) Founder A, LP, holds 100% of the shares of Class B common stock (which represents a majority of the combined voting power of the common stock) of TPG Inc.

F2 · ownership.nature: TPG Inc. is the sole member of TPG GPCo, LLC, which is the sole member of TPG Holdings II-A, LLC, which is the general partner of TPG Operating Group II, L.P., which is the sole member of TPG Holdings I-A, LLC, which is the general partner of TPG Operating Group I, L.P., which is the sole member of The Rise Fund GenPar Advisors, LLC, which is the general partner of The Rise Fund GenPar, L.P., which is the managing member of The Rise Fund SPV GP, LLC, which is the general partner of each of The Rise Fund Sling, L.P., which directly holds 5,476,598 shares of Common Stock ("Common Stock") of Sionna Therapeutics, Inc. (the "Issuer"), and The Rise Fund Sling II, L.P. (together with The Rise Fund Sling, L.P., the "TPG Funds"), which directly holds 1,208,364 shares of Common Stock.

F3 · ownership.nature: Pursuant to the Amended and Restated Certificate of Incorporation of the Issuer, as amended, the shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, in each case of the Issuer (collectively, the "Preferred Stock"), automatically converted into shares of Common Stock upon consummation of the Issuer's initial public offering on February 10, 2025 at a conversion rate (adjusted for a reverse stock split) equal to one share of Common Stock per 1.4611 share of Preferred Stock. The shares of Preferred Stock had previously been convertible, at the option of the holder, at any time into shares of Common Stock.

F5 · ownership.nature: Because of the relationship between the Reporting Persons and the TPG Funds, the Reporting Persons may be deemed to beneficially own the securities reported herein to the extent of the greater of their respective direct or indirect pecuniary interests in the profits or capital accounts of the TPG Funds. Each of the TPG Funds and each Reporting Person disclaims beneficial ownership of the securities reported herein, except to the extent of such TPG Fund's or such Reporting Person's pecuniary interest therein, if any.

F6 · ownership.nature: Pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), this filing shall not be deemed an admission that the Reporting Persons are, for purposes of Section 16 of the Exchange Act or otherwise, the beneficial owners of any equity securities in excess of their respective pecuniary interests.

SEC source: 0000950170-25-017027 · ownership.xml · derivative · entry 1

McKee Charlotte · CIK 0002046433 · Chief Medical Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 148,536

Underlying: Common Stock · 148,536 shares

Expires 2035-02-05

F1 · derivative.exercise_date: The shares underlying this option vest in forty-eight equal monthly installments following February 6, 2025, subject to the Reporting Person's continued service on each such vesting date.

SEC source: 0000950170-25-017037 · ownership.xml · derivative · entry 1

Ruddy Marcella K. · CIK 0002023849 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 39,919

Underlying: Common Stock · 39,919 shares

Expires 2035-02-05

F1 · derivative.exercise_date: The shares underlying this option vest in three equal annual installments following February 6, 2025, subject to the Reporting Person's continued service on each such vesting date.

SEC source: 0000950170-25-017036 · ownership.xml · derivative · entry 1

Viney Joanne L. · CIK 0001816744 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 39,919

Underlying: Common Stock · 39,919 shares

Expires 2035-02-05

F1 · derivative.exercise_date: The shares underlying this option vest in three equal annual installments following February 6, 2025, subject to the Reporting Person's continued service on each such vesting date.

SEC source: 0000950170-25-017034 · ownership.xml · derivative · entry 1

Cloonan Michael · CIK 0001704336 · Director · President & CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 450,252

Underlying: Common Stock · 450,252 shares

Expires 2035-02-05

F1 · derivative.exercise_date: The shares underlying this option vest in forty-eight equal monthly installments following February 6, 2025, subject to the Reporting Person's continued service on each such vesting date.

SEC source: 0000950170-25-017032 · ownership.xml · derivative · entry 1

Ridloff Elena · CIK 0001772518 · CFO & Head of Corp. Dev.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 157,820

Underlying: Common Stock · 157,820 shares

Expires 2035-02-05

F1 · derivative.exercise_date: The shares underlying this option vest in forty-eight equal monthly installments following February 6, 2025, subject to the Reporting Person's continued service on each such vesting date.