Company: SION
Filing Date: 2025-02-03
Form Type: S-1/A
Source: 0001193125-25-018825
Chunk: 346

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-03
Form: S-1/A
Chunk 346
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 not considered outstanding for accounting purposes. The voting, dividend and liquidation rights of the holders of the Company’s common stock are subject to and qualified by the rights, powers and preference of the holders of the Preferred Stock set forth in Note 10 above. The number of shares of common stock that have been reserved for the potential conversion of Preferred Stock, exercise of stock options, and vesting of restricted stock is as follows:

|                                  |     | Year Ended December 31, |       2023 |     |     |       2022 |
|:---------------------------------|:----|:------------------------|-----------:|:----|:----|-----------:|
| Convertible preferred stock      |     |                         | 14,399,245 |     |     | 14,399,245 |
| Options to purchase common stock |     |                         |  1,914,362 |     |     |  1,945,186 |
| Unvested restricted stock        |     |                         |    262,149 |     |     |    484,531 |
| Total                            |     |                         | 16,575,756 |     |     | 16,828,962 |

12. Stock-Based Compensation 2020 Stock Option and Grant Plan The Company’s 2020 Stock Option and Grant Plan, as amended (the “2020 Plan”), provides for the Company to sell or issue common stock or restricted common stock, or to grant incentive stock options or nonqualified stock options for the purchase of common stock, to employees, members of the Board and consultants of the Company. The 2020 Plan is administered by the Board, or at the discretion of the Board, by a committee of the Board. The exercise prices, vesting and other restrictions are determined at the discretion of the Board, or their committee if so delegated, except that the exercise price per share of stock options may not be less than 100% of the fair market value of the share of common stock on the date of grant and the term of stock option may not be greater than ten years. F-23

The total number of shares of common stock that may be issued under the 2020 Plan is 3,949,579 shares, of which 775,423 remained available for future grant as of December 31, 2023. Vesting periods are determined at the discretion of the Board. Stock options and restricted stock granted to-datetypically vest over four years. Restricted Common Stock The