Company: SION
Filing Date: 2025-02-07
Form Type: 424B4
Source: 0001193125-25-022709
Chunk: 316

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-07
Form: 424B4
Chunk 316
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 in the Offered
Securities Rules of the DFSA. It must not be delivered to, or relied on by, any other person. The DFSA has no responsibility for reviewing or verifying any documents in connection with Exempt Offers. The DFSA has not approved this prospectus nor
taken steps to verify the information set forth in this prospectus and has no responsibility for the offering document. The securities to which this offering document relates may be illiquid and/or subject to restrictions on their resale.
Prospective purchasers of the securities offered should conduct their own due diligence on the securities. If you do not understand the contents of this offering document you should consult an authorized financial advisor.

227

Switzerland

This offering document is not intended to constitute an offer or solicitation to purchase or invest in the shares of our common stock. The shares of
common stock may not be publicly offered, directly or indirectly, in Switzerland within the meaning of the Swiss Financial Services Act (“FinSA”), and no application has or will be made to admit the shares of common stock to trading on any
trading venue (exchange or multilateral trading facility) in Switzerland. Neither this offering document nor any other offering or marketing material relating to the shares of common stock constitutes a prospectus pursuant to the FinSA, and neither
this offering document nor any other offering or marketing material relating to the shares of common stock may be publicly distributed or otherwise made publicly available in Switzerland.

Neither this offering document nor any other offering or marketing material relating to the offering, us or the securities have been or will be filed
with or approved by any Swiss regulatory authority. In particular, this offering document will not be filed with, and the offer of securities will not be supervised by, the Swiss Financial Market Supervisory Authority, and the offer of securities
has not been and will not be authorized under the Swiss Federal Act on Collective Investment Schemes (“CISA”). The investor protection afforded to acquirers of interests in collective investment schemes under the CISA does not extend to
acquirers of securities.

Brazil

The offer and
sale of the securities have not been and will not be registered with the Brazilian Securities Commission (Comissão de Valores Mobiliários, or “CVM”) and, therefore, will not be carried out by any means that would constitute a
public offering in Brazil under CVM Resolution No 160, dated 13 July 2022, as amended (“CVM Resolution 160”) or unauthorized distribution under Brazilian laws and regulations. The securities