Company: SION
Filing Date: 2025-02-03
Form Type: S-1/A
Source: 0001193125-25-018825
Chunk: 340

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-03
Form: S-1/A
Chunk 340
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 of its office and laboratory space under the Waltham Lease (the “Sublease”). The Company was not relieved of its obligation to the lessor for the head lease as a result of its entry into the Sublease. The Sublease is classified as an operating lease and commenced in July 2023 and has an original term of 26 months with the option to extend for an additional six months. The Sublease has escalating rent payments and is secured by a letter of credit of $0.2 million with the Company named as the beneficiary. Sublease income is recognized on a straight-line basis and the rental income and reimbursement for operating expenses and taxes is included in other income on the consolidated statements of operations and comprehensive loss. As of December 31, 2023, the Company recognized $0.3 million of sublease income within other income on the consolidated statements of operations and comprehensive loss, and recognized no sublease income for the year ended December 31, 2022. Operating Lease Tables The following table presents weighted average remaining lease term and discount rates which are used in the calculation of the Company’s right of use asset and lease liabilities at the end of each reporting period:

|                                                                                  |     | December 31, |      |   |     |      |     |   |
|                                                                                  |     |         2023 |      |   |     | 2022 |     |   |
| Weighted average remaining lease term (years)                                    |     |              |  6.9 |   |     |      |   — |   |
| Weighted average discount rate                                                   |     |              | 11.0 | % |     |      | 9.0 | % |
| Cash paid for amounts included in the measurement of operating lease liabilities 
 (in thousands)                                                                   |     |            $ |  172 |   |     |    $ |   — |   |

The components of lease costs were as follows (in thousands):

|                        |     | December 31, |  2023 |     |   | 2022 |
|:-----------------------|:----|:-------------|------:|:----|:--|-----:|
| Operating lease costs  |     | $            | 1,824 |     | $ |    — |
| Variable lease costs   |     |              |   468 |     |   |    — |
| Short-term lease costs |     |              |    88 |     |   |  207