SION insider files Form 144 to sell 54,637 common shares via Merrill Lynch

Rhea-AI Filing Summary

Sionna Therapeutics filed a Form 144 reporting a proposed sale of common stock. The notice shows 54,637 shares to be sold through Merrill Lynch on NASDAQ, with an aggregate market value of $1,581,194.78 and approximately 44,139,823 shares outstanding. The shares were acquired in a private placement from the issuer on 03/04/2024 and paid in cash on that date. The filing states there were no securities sold by the reporting person in the past three months. The notice includes the standard representation that the seller is not aware of any undisclosed material adverse information.

Positive

• Acquisition and payment were completed in cash on 03/04/2024, indicating clear title to the shares
• No securities sold in the prior three months by the reporting person, simplifying interpretation of trading activity

Negative

• Proposed sale of 54,637 shares (aggregate market value $1,581,194.78) is scheduled, which may indicate insider liquidity
• Sale set for 09/29/2025, creating a future supply event that could modestly increase sell-side pressure on the stock that day

Insights

Securities Analyst

TL;DR: Insider/affiliate plans a modest sale of 54,637 common shares valued at $1.58M; transaction originated from a private placement.

The Form 144 discloses a proposed sale executed through Merrill Lynch on NASDAQ, listing the security class, quantity, and aggregate value. The shares were acquired via a private placement from the issuer on 03/04/2024 and fully paid in cash that same day. There are no reported sales by the filer in the prior three months, which limits near-term disposition history. Relative to the ~44.14 million shares outstanding, the amount represents a small fraction of the float, suggesting limited direct dilution or market impact. The filing contains the routine attestation regarding undisclosed material adverse information.

Corporate Governance Expert

TL;DR: Routine disclosure of a planned sale by a person who acquired shares in a private placement; governance signal is neutral.

The notice follows Rule 144 requirements by identifying the broker, proposed sale date (09/29/2025), and acquisition details. Because the acquisition was from the issuer via private placement, the filing clarifies the holding origin and payment method. The absence of other recent sales reduces complexity in assessing trading pattern. The standard seller representation about material information is present. Overall, this is a compliance-focused filing rather than an event that by itself implies a corporate governance change.

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	Merrill Lynch 555 California Street 18th Floor San Francisco CA 94104	54637	1581194.78	44139823	09/29/2025	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	03/04/2024	Private Placement	Issuer			54637	03/04/2024	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 SION Form 144 report?

The filing reports a proposed sale of 54,637 common shares through Merrill Lynch on NASDAQ with an aggregate market value of $1,581,194.78.

When were the shares acquired that are being sold under the Form 144?

The shares were acquired in a private placement from the issuer and paid in cash on 03/04/2024.

Who is the broker handling the proposed sale in the SION Form 144?

The broker named in the filing is Merrill Lynch, 555 California Street, 18th Floor, San Francisco, CA.

What is the approximate share count outstanding used in the filing?

The filing lists 44,139,823 shares outstanding for the issuer.

Are there any other sales by the filer in the past three months?

The Form 144 states Nothing to Report for securities sold during the past three months.