[Form 4] Sionna Therapeutics, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Jennifer Fitzpatrick, Chief Legal Officer of Sionna Therapeutics, reported transactions on 09/04/2025 under a Rule 10b5-1 plan. She exercised a non-qualified stock option to purchase 10,250 shares at an exercise price of $6.11 per share and immediately sold 10,250 common shares at a weighted-average price of $23.12, with individual sale prices ranging from $21.80 to $24.52. Following these transactions, she reports 0 shares beneficially owned. The option vests 25% on June 3, 2025, with the remainder vesting monthly over 36 months.

Positive

• Exercise and sale executed under a Rule 10b5-1 plan, indicating trades were preplanned (plan adopted June 5, 2025).
• Full disclosure of weighted-average sale price range ($21.80 to $24.52) and willingness to provide per-trade details upon request.

Negative

• Reported beneficial ownership reduced to 0 shares after the sales, which may be notable given the reporting person’s officer status.
• Immediate sale of all exercised shares removes insider share ownership disclosed in this filing.

Insights

Securities Analyst

TL;DR Insider exercised options at $6.11 and sold the resulting 10,250 shares via a 10b5-1 plan at a ~$23.12 average, leaving no reported holdings.

The transaction is a routine, preplanned insider sale executed under a Rule 10b5-1 arrangement, which provides regulatory safe harbor for trading while in possession of material nonpublic information. The exercise captured intrinsic value between the $6.11 strike and the reported sale prices, realizing a substantial gross spread per share. Because the reporting person is an officer and the sale reduced reported beneficial ownership to zero, investors may note the change in insider exposure but the filing itself does not provide information about reasons for the sale or company fundamentals.

Corporate Governance Expert

TL;DR Transaction follows a documented 10b5-1 plan; disclosure and price ranges are provided—no indications of governance breaches in the filing.

The filing discloses the adoption date of the 10b5-1 plan (June 5, 2025) and price ranges for the executed sales, enhancing transparency. Vesting schedule details for the option are included, clarifying the option economics and remaining vesting cadence. From a governance perspective, the use of a pre-established trading plan and the explicit offer to provide granular sale-level data on request align with standard disclosure practices.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

X

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Fitzpatrick Jennifer

(Last) (First) (Middle)

C/O SIONNA THERAPEUTICS, INC.

21 HICKORY DRIVE, SUITE 500

(Street)

WALTHAM MA 02451

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Sionna Therapeutics, Inc. [ SION ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Legal Officer

3. Date of Earliest Transaction (Month/Day/Year)
09/04/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	09/04/2025		M(1)		10,250	A	$6.11	10,250	D
Common Stock	09/04/2025		S(1)		10,250	D	$23.12(2)	0	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Non-Qualified Stock Option (right to buy)	$6.11	09/04/2025		M			10,250	(3)	07/14/2034	Common Stock	10,250	$0.0	71,435	D

Explanation of Responses:

1. This transaction was automatically executed pursuant to a Rule 10b5-1 trading plan adopted on June 5, 2025.

2. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $21.80 to $24.52, inclusive. The Reporting Person undertakes to provide to the Issuer, any sercurityholder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price at which the transactions were effected.

3. 25% of the shares underlying this option vested on June 3, 2025, with the remainder vesting in thirty-six equal monthly installments thereafter, subject to the Reporting Person's continued service on each such vesting date.

	Jennifer Fitzpatrick	09/05/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What did Jennifer Fitzpatrick (SION) do on 09/04/2025?

She exercised a non-qualified option for 10,250 shares at $6.11 and sold 10,250 shares at a weighted-average of $23.12 under a 10b5-1 plan.

Was the sale part of a preplanned trading program?

Yes. The transactions were automatically executed pursuant to a Rule 10b5-1 plan adopted on June 5, 2025.

How many shares does Fitzpatrick report owning after the transactions?

0 shares beneficially owned following the reported transactions.

What was the range of sale prices for the shares sold?

Shares were sold at prices ranging from $21.80 to $24.52, with a reported weighted-average sale price of $23.12.

What are the option vesting terms disclosed?

The option vested 25% on June 3, 2025; the remainder vests in 36 equal monthly installments thereafter, subject to continued service.