17,340 Sion (SION) options granted for RA Capital-linked funds

Rhea-AI Filing Summary

Sionna Therapeutics, Inc. reported a Form 4 showing a grant of a non-qualified stock option covering 17,340 shares of common stock. The option has an exercise price of $36.73 per share and expires on June 16, 2036.

According to the footnotes, Dr. Resnick holds this option for the benefit of RA Capital-managed vehicles, and any net cash or stock from exercise will offset advisory fees owed to those funds. RA Capital Management, affiliated funds, and their principals disclaim beneficial ownership of the option and underlying shares except for any pecuniary interest.

Insights

Biotech equity & insider-transactions analyst

Routine compensation-related option grant routed through RA Capital structures.

This filing records a grant of a non-qualified stock option for 17,340 Sionna Therapeutics shares at an exercise price of $36.73, expiring on June 16, 2036. The grant is classified as a derivative acquisition, not an open-market purchase or sale.

Footnotes clarify that Dr. Resnick holds the option for the benefit of RA Capital-managed funds and a separately managed account, with any exercise proceeds used to offset advisory fees. The reporting entities and individuals disclaim beneficial ownership beyond their pecuniary interest, suggesting a fee and incentive structure rather than a discretionary trading decision.

Because this is a single award with no concurrent sales and no remaining derivative positions disclosed in this filing, it appears as a standard governance and compensation arrangement. Its impact on the broader investment thesis for Sionna Therapeutics is limited and primarily administrative.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider RA CAPITAL MANAGEMENT, L.P., RA Capital Healthcare Fund LP, RA Capital Nexus Fund, L.P., RA Capital Nexus Fund III, L.P., Kolchinsky Peter, Shah Rajeev M.

Role null | null | null | null | null | null

Type	Security	Shares	Price	Value
Grant/Award	Non-Qualified Stock Option (right to buy)	17,340	$0.00	--

Holdings After Transaction: Non-Qualified Stock Option (right to buy) — 17,340 shares (Indirect, See Footnotes)

Footnotes (1)

1. The shares underlying the option vest in full upon the earlier of June 17, 2027 or the date of the Issuer's next annual meeting, subject to Dr. Resnick's continued service through such date. RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund"), RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus Fund III, 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. Each of the Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his pecuniary interest therein. Under Dr. Resnick's arrangement with the Adviser, Dr. Resnick holds the option for the benefit of the Fund, the Nexus Fund, the Nexus Fund III, and the Account. Dr. Resnick is obligated to turn over to the Adviser any net cash or stock received upon exercise of the stock option, which will offset advisory fees owed by the Fund, the Nexus Fund, the Nexus Fund III and the Account to the Adviser. The Reporting Persons therefore disclaim beneficial ownership of the stock option and underlying Common Stock.

Key Figures

Option grant size: 17,340 shares Exercise price: $36.73 per share Shares after transaction: 17,340 derivative shares +2 more

5 metrics

Option grant size 17,340 shares Non-qualified stock option underlying common stock

Exercise price $36.73 per share Non-qualified stock option strike price

Shares after transaction 17,340 derivative shares Total option shares following grant

Expiration date June 16, 2036 Option term end

Vesting trigger Earlier of June 17, 2027 or next annual meeting Subject to continued service of Dr. Resnick

Key Terms

Non-Qualified Stock Option, beneficial ownership, pecuniary interest, separately managed account, +1 more

5 terms

Non-Qualified Stock Option financial

"Non-Qualified Stock Option (right to buy)"

A non-qualified stock option (NSO) is a contract that lets an employee or service provider buy company shares at a fixed price for a set period, like a voucher to purchase stock later at today’s price. It matters to investors because exercising NSOs creates ordinary income for the holder and can increase share count, affecting a company’s earnings and ownership mix; think of it as a future sale that can dilute existing shareholders and has immediate tax consequences for the recipient.

beneficial ownership financial

"disclaims beneficial ownership of any of the reported securities"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

pecuniary interest financial

"except to the extent of its or his pecuniary interest therein"

separately managed account financial

"and a separately managed account (the "Account")"

A separately managed account (SMA) is a personalized investment portfolio owned by a single investor and run by a professional manager who buys and sells securities on that investor’s behalf. It matters to investors because an SMA offers tailored asset selection, tax handling, and transparency—like hiring a personal chef who prepares meals to your dietary needs rather than sharing a set menu—so you can align holdings with your goals and see exactly what you own.

advisory fees financial

"which will offset advisory fees owed by the Fund"

Advisory fees are payments made to financial advisors or investment managers for guidance, portfolio management, or other services, typically charged as a fixed amount or a percentage of assets under management. They matter because they lower an investor’s net returns—like paying a mechanic to tune a car, you expect better performance, so investors weigh whether the cost is justified by higher returns, better risk control, or convenience.

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 06/18/2026 - 05:42 PM Accepted by SEC EDGAR 06/18/2026 - 05:41 PM Learn about SEC filing dates

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 MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

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)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/17/2026

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

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

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

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

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)	$36.73	06/17/2026		A		17,340		(1)	06/16/2036	Common Stock	17,340	$0	17,340	I	See Footnotes(2)(3)

1. Name and Address of Reporting Person^*

RA CAPITAL MANAGEMENT, L.P.

(Last) (First) (Middle)

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

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 MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

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 MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

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 MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

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 MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

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 MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

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

Explanation of Responses:

1. The shares underlying the option vest in full upon the earlier of June 17, 2027 or the date of the Issuer's next annual meeting, subject to Dr. Resnick's continued service through such date.

2. RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund"), RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus Fund III, 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. Each of the Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his pecuniary interest therein.

3. Under Dr. Resnick's arrangement with the Adviser, Dr. Resnick holds the option for the benefit of the Fund, the Nexus Fund, the Nexus Fund III, and the Account. Dr. Resnick is obligated to turn over to the Adviser any net cash or stock received upon exercise of the stock option, which will offset advisory fees owed by the Fund, the Nexus Fund, the Nexus Fund III and the Account to the Adviser. The Reporting Persons therefore disclaim beneficial ownership of the stock option and underlying Common Stock.

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.	06/18/2026
	/s/ Peter Kolchinsky, Manager of RA Capital Healthcare Fund GP, LLC, the General Partner of RA Capital Healthcare Fund, L.P.	06/18/2026
	/s/ Peter Kolchinsky, Manager of RA Capital Nexus Fund GP, LLC, the General Partner of RA Capital Nexus Fund, L.P.	06/18/2026
	/s/ Peter Kolchinsky, Manager of RA Capital Nexus Fund III GP, LLC, the General Partner of RA Capital Nexus Fund III, L.P.	06/18/2026
	/s/ Peter Kolchinsky, individually	06/18/2026
	/s/ Rajeev Shah, individually	06/18/2026
	** 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.
* Form 4: SEC 1474 (03-26)

FAQ

What insider transaction did Sionna Therapeutics (SION) report in this Form 4?

Sionna Therapeutics reported a grant of a non-qualified stock option for 17,340 shares of common stock at a $36.73 exercise price. The option is a derivative award, not an open-market stock purchase or sale, and expires on June 16, 2036.

Who effectively benefits from the new Sionna Therapeutics (SION) stock option grant?

The option is held by Dr. Resnick for the benefit of RA Capital Healthcare Fund, RA Capital Nexus Fund, RA Capital Nexus Fund III, and a separately managed account. Net cash or stock from any exercise will offset advisory fees owed to RA Capital Management.

How and when does the new Sionna Therapeutics (SION) option grant vest?

The shares underlying the option vest in full on the earlier of June 17, 2027, or the date of Sionna Therapeutics’ next annual meeting. Vesting is conditioned on Dr. Resnick’s continued service through that date, according to the footnote disclosure.

Do RA Capital-related reporting persons claim beneficial ownership of the SION option grant?

RA Capital Management, its affiliated funds, their general partner, and principals Dr. Kolchinsky and Mr. Shah disclaim beneficial ownership of the option and underlying SION common stock, except for any pecuniary interest. The filing emphasizes this limitation in multiple detailed footnotes.

Is the Sionna Therapeutics (SION) Form 4 transaction a stock purchase or sale?

No, the transaction is a grant of a non-qualified stock option classified as a derivative acquisition with code A. It does not represent an open-market purchase or sale of SION shares, but an award that may be exercised later at $36.73 per share.