RA Capital funds report SION insider stock sales in Form 4 filing

Rhea-AI Filing Summary

Sionna Therapeutics, Inc. (SION)11/20/2025 and 11/21/2025, these reporting persons sold multiple small blocks of Sionna common stock in open-market transactions.

The weighted average sale prices ranged from about $39.40 to $40.51 per share, with examples including 9,924 shares sold at a weighted average price of $39.50 and 801 shares sold at a weighted average price of $39.89. After these trades, the reported beneficial holdings for the various RA Capital funds and accounts remained large, such as 6,897,623 shares for one fund and over 2.1 million shares for another, as disclosed in the table.

11/24/2025 - 05:43 PM

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).

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^*

RA CAPITAL MANAGEMENT, L.P.

(Last) (First) (Middle)

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MA 02116

(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)

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

3. Date of Earliest Transaction (Month/Day/Year)
11/20/2025

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

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

	Form filed by One Reporting Person
X	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	11/20/2025		S		150	D	$39.89(1)	6,898,929	I	See footnotes(2)(3)
Common Stock	11/20/2025		S		1,235	D	$39.89(1)	661,019	I	See footnotes(3)(4)
Common Stock	11/20/2025		S		801	D	$39.89(1)	2,205,034	I	See footnotes(3)(5)
Common Stock	11/20/2025		S		947	D	$39.89(1)	167,246	I	See footnotes(3)(6)
Common Stock	11/20/2025		S		96	D	$40.5(7)	6,898,833	I	See footnotes(2)(3)
Common Stock	11/20/2025		S		788	D	$40.5(7)	660,231	I	See footnotes(3)(4)
Common Stock	11/20/2025		S		512	D	$40.5(7)	2,204,522	I	See footnotes(3)(5)
Common Stock	11/20/2025		S		604	D	$40.5(7)	166,642	I	See footnotes(3)(6)
Common Stock	11/21/2025		S		1,210	D	$39.5(8)	6,897,623	I	See footnotes(2)(3)
Common Stock	11/21/2025		S		9,924	D	$39.5(8)	650,307	I	See footnotes(3)(4)
Common Stock	11/21/2025		S		6,440	D	$39.5(8)	2,198,082	I	See footnotes(3)(5)
Common Stock	11/21/2025		S		7,609	D	$39.5(8)	159,033	I	See footnotes(3)(6)

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

1. Name and Address of Reporting Person^*

RA CAPITAL MANAGEMENT, L.P.

(Last) (First) (Middle)

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MA 02116

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

RA Capital Healthcare Fund LP

(Last) (First) (Middle)

C/O RA CAPITAL MANAGEMENT, L.P.

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MA 02116

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

RA Capital Nexus Fund, L.P.

(Last) (First) (Middle)

C/O RA CAPITAL MANAGEMENT, L.P.

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MA 02116

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

RA Capital Nexus Fund III, L.P.

(Last) (First) (Middle)

C/O RA CAPITAL MANAGEMENT, L.P.

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MA 02116

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Kolchinsky Peter

(Last) (First) (Middle)

C/O RA CAPITAL MANAGEMENT, L.P.

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MA 02116

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Shah Rajeev M.

(Last) (First) (Middle)

C/O RA CAPITAL MANAGEMENT, L.P.

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MA 02116

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

Explanation of Responses:

1. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $39.40 to $40.00 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder 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 within the range set forth in this footnote.

2. Held directly by RA Capital Healthcare Fund, L.P. (the "Fund").

3. RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund, RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus III Fund, L.P. (the "Nexus Fund III"), and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. The Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.

4. Held directly by the Nexus Fund.

5. Held directly by the Nexus Fund III.

6. Held directly by the Account.

7. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $40.50 to $40.51 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder 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 within the range set forth in this footnote.

8. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $39.50 to $40.00 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder 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 within the range set forth in this footnote.

Remarks:

Joshua Resnick, a Partner of the Adviser, serves on the Issuer's board of directors.

	/s/ Peter Kolchinsky, Manager of RA Capital Management, L.P.	11/24/2025
	/s/ Peter Kolchinsky, Manager of RA Capital Healthcare Fund GP, LLC, the General Partner of RA Capital Healthcare Fund, L.P.	11/24/2025
	/s/ Peter Kolchinsky, Manager of RA Capital Nexus Fund GP, LLC, the General Partner of RA Capital Nexus Fund, L.P.	11/24/2025
	/s/ Peter Kolchinsky, Manager of RA Capital Nexus Fund III GP, LLC, the General Partner of RA Capital Nexus Fund III, L.P.	11/24/2025
	/s/ Peter Kolchinsky, individually	11/24/2025
	/s/ Rajeev Shah, individually	11/24/2025
	** 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.
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FAQ

What does the latest Sionna Therapeutics (SION) Form 4 report?

The Form 4 reports that RA Capital–affiliated funds and individuals, who are directors and in some cases 10% owners of Sionna Therapeutics (SION), sold multiple blocks of common stock in open-market transactions on 11/20/2025 and 11/21/2025.

How many Sionna (SION) shares were sold in the reported Form 4 transactions?

The filing lists several separate sales, including examples such as 9,924 shares of common stock and 7,609 shares sold on 11/21/2025, and smaller blocks such as 1,235 and 801 shares sold on 11/20/2025, each disclosed as individual line items.

At what prices were the Sionna Therapeutics (SION) shares sold?

The reported sales used weighted average prices. Footnotes state that trades on 11/20/2025 were executed in ranges from $39.40 to $40.00 and from $40.50 to $40.51, while trades on 11/21/2025 were in a range from $39.50 to $40.00.

How many Sionna (SION) shares do the RA Capital entities report owning after these trades?

After the transactions, the table shows large remaining positions, including 6,897,623 shares beneficially owned by one RA Capital fund, 650,307 shares by another fund, and 2,198,082 shares by a third fund, among others listed.

Who are the reporting persons on this Sionna Therapeutics (SION) Form 4?

The reporting persons include RA Capital Healthcare Fund, L.P., RA Capital Nexus Fund, L.P., RA Capital Nexus III Fund, L.P., a separately managed account, RA Capital Management, L.P., its general partner, and individuals including Dr. Peter Kolchinsky and Rajeev Shah, all filing jointly.

What relationships do the RA Capital affiliates have with Sionna Therapeutics (SION)?

The Form 4 indicates that several of the reporting persons are directors of Sionna Therapeutics and that some are also 10% owners. It also notes that Joshua Resnick, a partner of the adviser, serves on the company’s board of directors.

Do the RA Capital entities claim full beneficial ownership of all reported Sionna (SION) shares?

A footnote explains that the adviser, its general partner, the funds, and the individuals disclaim beneficial ownership of the reported securities, except to the extent of their pecuniary interest in those securities.