Company: SION
Filing Date: 2025-02-07
Form Type: 424B4
Source: 0001193125-25-022709
Chunk: 138

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-07
Form: 424B4
Chunk 138
---
 activities. These increases will likely include increased costs related to the hiring of additional personnel and fees paid to outside consultants, among other expenses. We also anticipate increased expenses
related to audit, accounting, legal and regulatory services associated with public company reporting and compliance, director and officer insurance premiums, investor and public relations costs and other administrative and professional services
associated with operating as a public company.

Interest Income

Interest income consists primarily of interest earned and the amortization of discount or premiums on our cash equivalents and investments in marketable
securities. We expect our interest income will increase as we invest the cash received from the net proceeds from this offering.

Other Income

Other income consists of sublease income through our subleasing agreement which is further discussed within Note 7, “Leases” in our
consolidated financial statements included elsewhere in this prospectus.

Income Taxes

Since our inception, we have not recorded any income tax benefits for the net losses we have incurred in each period or for our earned research and
development tax credits, as we believe, based upon the weight of available evidence, that it is more likely than not that all of our net operating loss carryforwards and tax credits will not be realized.

As of December 31, 2023, we had $48.2 million and $47.1 million of federal and state operating loss carryforwards, respectively. The
federal NOLs are not subject to expiration and the state NOLs begin to expire in 2043. These loss carryforwards are available to reduce future federal taxable income, if any. As of the nine months ended September 30, 2024 and 2023, and the
years ended December 31, 2023 and 2022, we have recorded a full valuation allowance against our net deferred tax assets.

100

Results of Operations Comparison of the Nine Months Ended September 30, 2024 and 2023 The following table summarizes our results of operations (in thousands):

| Operating expenses:        | 2024 | Nine Months         
 Ended September 30, |         |   | 2023 |   |         |   |     | Change |         |   |
|:---------------------------|:-----|:--------------------|--------:|:--|:-----|:--|--------:|:--|:----|:-------|--------:|:--|
| Research and development   |      | $                   |  43,035 |   |      | $ |