TPG GP A, LLC bought SION

Footnotes

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.; 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 5,536,598 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.; 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.; 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.