Company: SION
Filing Date: 2025-01-17
Form Type: S-1
Source: 0001193125-25-008474
Chunk: 295

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-01-17
Form: S-1
Chunk 295
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 hold our common stock as a “capital asset” within the meaning of Section 1221 of the Code (generally, property held for investment). This discussion is not a complete analysis of all potential U.S. federal income or estate tax consequences relating thereto, does not address the potential application of the Medicare contribution tax on net investment income, the alternative minimum tax, or the special tax accounting rules under Section 451(b) of the Code, and also does not address any U.S. federal non-incometax consequences, such as estate or gift tax consequences, or any tax consequences arising under any state, local or foreign tax laws. This discussion does not address all of the U.S. federal income or estate tax consequences that may be relevant to a non-U.S.holder in light of such non-U.S.holder’s particular circumstances. This discussion also does not consider any specific facts or circumstances that may be relevant to non-U.S.holders subject to special rules under the U.S. federal income or estate tax laws, including:

| • |     | U.S. expatriates, former citizens or long-term residents of the U.S.; |

| • |     | partnerships or other entities or arrangements treated as pass-through or disregarded entities for U.S. federal income tax 
 purposes (and investors therein);                                                                                          |

| • |     | “controlled foreign corporations”; |

| • |     | “passive foreign investment companies”; |

| • |     | corporations that accumulate earnings to avoid U.S. federal income tax; |

| • |     | banks, financial institutions, investment funds, insurance companies, brokers, dealers or traders in securities; |

| • |     | tax-exempt organizations and governmental organizations; |

| • |     | tax-qualified retirement plans; |

| • |     | persons who acquire our common stock through the exercise of an option or otherwise as compensation; |

| • |     | qualified foreign pension funds as defined in Section 897(l)(2) of the Code and entities all of the interests of which 
 are held by qualified foreign pension funds;                                                                           |

| • |     | persons that elect to apply Section 1400Z-2 of the Code to gains recognized 
 with respect to shares of our common stock;                                 |

| • |     | persons that own or have owned, actually or constructively, more than 5% of our common stock; |

| • |     | persons who have elected to mark securities to market; and |

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