[144] Sionna Therapeutics, Inc. SEC Filing

Rhea-AI Filing Summary

Sionna Therapeutics, Inc. (SION) filing a Form 144 notifies a proposed sale of 10,250 common shares via Morgan Stanley Smith Barney on NASDAQ with an aggregate market value of $251,637.50. The shares were acquired and paid for on 09/04/2025 through exercise of stock options from the issuer. The filing lists 44,139,823 shares outstanding and reports no other sales by the seller in the past three months. The filer certifies no undisclosed material adverse information.

Positive

• Timely disclosure of proposed sale via Form 144 meets regulatory notice requirements
• Transaction sourced from option exercise and fully paid on the acquisition date (09/04/2025)
• No other sales in past three months reported for the seller

Negative

• Insider sale of shares could be perceived negatively by some investors despite being small
• Limited contextual information about the identity of the selling person and motive is not provided in the filing

Insights

Securities Analyst

TL;DR Insider exercised options and plans a small public sale representing a negligible fraction of outstanding shares.

The filing documents a routine Form 144 sale following an option exercise and immediate payment on 09/04/2025. At 10,250 shares valued at $251,637.50 against 44,139,823 shares outstanding, the position is immaterial to capitalization and unlikely to move the market. Timely disclosure via Form 144 satisfies Rule 144 notice requirements and shows compliance with resale regulations.

Corporate Governance Expert

TL;DR The notice reflects standard insider liquidity post-exercise with required certifications about material information.

The filer affirms no nonpublic material adverse information and indicates no prior sales in the past three months. This aligns with disclosure expectations for insiders selling securities obtained from option exercises. The broker identified and the exchange specified (NASDAQ) provide clear execution pathways. The disclosure does not raise governance or compliance concerns based on the provided facts.

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	10250	251637.50	44139823	09/04/2025	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	09/04/2025	Exercise of Stock Options	Issuer			10250	09/04/2025	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 is being reported in the SION Form 144?

The filing reports a proposed sale of 10,250 common shares valued at $251,637.50, to be sold on NASDAQ through Morgan Stanley Smith Barney.

When were the shares acquired and how were they paid for?

The shares were acquired and paid for on 09/04/2025 via exercise of stock options with payment in cash.

How large is the sale relative to Sionna's outstanding shares?

The proposed sale is 10,250 shares versus 44,139,823 shares outstanding, representing an immaterial percentage of total shares.

Did the filer report any other sales in the past three months?

The Form 144 indicates Nothing to Report for securities sold during the past three months by the seller.

Which broker and exchange are named for the sale?

The broker is Morgan Stanley Smith Barney LLC and the exchange is specified as NASDAQ.