Company: SION
Filing Date: 2025-02-03
Form Type: S-1/A
Source: 0001193125-25-018825
Chunk: 308

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-03
Form: S-1/A
Chunk 308
---
 the underwriters named below have entered into an underwriting agreement with respect to the shares being offered. Subject to certain conditions, each underwriter has severally agreed to purchase the number of shares indicated in the following table. Goldman Sachs & Co. LLC, TD Securities (USA) LLC, Stifel, Nicolaus & Company, Incorporated and Guggenheim Securities, LLC are the representatives of the underwriters.

| Underwriters                             |     | Number    
 of Shares |           |
| Goldman Sachs & Co. LLC                  |     |           |           |
| TD Securities (USA) LLC                  |     |           |           |
| Stifel, Nicolaus & Company, Incorporated |     |           |           |
| Guggenheim Securities, LLC               |     |           |           |
| Total                                    |     |           | 8,823,529 |

The underwriters are committed to take and pay for all of the shares being offered, if any are taken, other than the shares covered by the option described below unless and until this option is exercised. The underwriters have an option to buy up to an additional 1,323,529 shares from the company to cover sales by the underwriters of a greater number of shares than the total number set forth in the table above. The underwriters may exercise that option for 30 days from the date of this prospectus. If any shares are purchased pursuant to this option, the underwriters will severally purchase shares in approximately the same proportion as set forth in the table above. The following table shows the per share and total underwriting discounts and commissions to be paid to the underwriters by the company. Such amounts are shown assuming both no exercise and full exercise of the underwriters’ option to purchase 1,323,529 additional shares. Paid by the Company

|           |     | No       
 Exercise |     | Full     
 Exercise |
|:----------|:----|:---------|:----|:---------|
| Per Share |     | $        |     | $        |
| Total     |     | $        |     | $        |

Shares sold by the underwriters to the public will initially be offered at the initial public offering price set forth on the cover of this prospectus. Any shares sold by the underwriters to securities dealers may be sold at a discount of up to $ per share from the initial public offering price. After the initial offering of the shares, the representatives may change the offering price and the other selling terms. The offering of the shares