[144] Sionna Therapeutics, Inc. SEC Filing

Rhea-AI Filing Summary

Sionna Therapeutics (SION) filing of a Form 144 notifies the proposed sale of 34,500 shares of common stock through Morgan Stanley Smith Barney LLC on 08/19/2025. The shares have an aggregate market value of $737,955.00 and the company reports 44,139,823 shares outstanding. The securities were acquired on 09/20/2022 through previously exercised stock options from the issuer and were paid for in cash. The filer reports "Nothing to Report" for securities sold during the past three months. The notice includes the filers representation that they do not possess undisclosed material adverse information.

Positive

• Regulatory compliance: The filer provided required Rule 144 disclosure details, including broker, share count, and acquisition history.
• Transparency: Acquisition date (09/20/2022) and payment method (cash) are disclosed, aiding market clarity.

Negative

• Insider sale planned: The proposed sale of 34,500 shares by an insider may be perceived negatively by some investors.

Insights

Securities Analyst

TL;DR: Routine insider notice of proposed sale; transparent reporting but not materially transformative.

The Form 144 documents a planned sale of 34,500 common shares via Morgan Stanley Smith Barney LLC with an aggregate market value of $737,955. The shares were acquired by previously exercised options on 09/20/2022 and paid in cash. The filing states no sales in the past three months. This is a standard regulatory disclosure that enables market transparency about an insider-affiliated sale. The filing itself contains no earnings, financing, or covenant changes and does not disclose any undisclosed adverse information per the signers representation.

Corporate Governance Expert

TL;DR: Proper compliance with Rule 144 reporting requirements; procedural rather than material news.

The notice provides required details: broker name and address, number of shares, acquisition date and method (previously exercised stock options), and payment nature (cash). It confirms no related sales in the prior three months and includes the standard signature representation about material information. From a governance perspective, the filing demonstrates adherence to disclosure rules but does not, by itself, indicate governance changes or material corporate events.

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK
Filer CCC
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer

SEC File Number

Address of Issuer

Phone

Name of Person for Whose Account the Securities are To Be Sold

See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.

Relationship to Issuer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common	Morgan Stanley Smith Barney LLC Executive Financial Services 1 New York Plaza 8th Floor New York NY 10004	34500	737955.00	44139823	08/19/2025	NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common	09/20/2022	Previously Exercised Stock Options	Issuer			34500	09/20/2022	Cash

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Nothing to Report

144: Remarks and Signature

Remarks

Date of Notice

Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1

ATTENTION:

The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.

Signature

ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)

FAQ

What does the Form 144 for SION disclose?

The Form 144 discloses a proposed sale of 34,500 common shares through Morgan Stanley Smith Barney LLC on 08/19/2025 with an aggregate market value of $737,955.00.

How and when were the shares being sold acquired?

The shares were acquired on 09/20/2022 via previously exercised stock options from the issuer and were paid for in cash.

Does the filing report recent sales by the same person?

The filing states "Nothing to Report" for securities sold during the past three months.

How many shares outstanding does Sionna report in this notice?

The notice lists 44,139,823 shares outstanding.

Which broker is handling the proposed sale?

The broker named in the filing is Morgan Stanley Smith Barney LLC, Executive Financial Services, 1 New York Plaza, 8th Floor, New York NY 10004.