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SION · Current Report (Form 8-K) · Filed June 18, 2026

Sionna Therapeutics Inc — Current Report (Form 8-K)

Form
8-K
Filed
June 18, 2026
Period
Jun 17, 2026
Ticker
SION
Accession
0001628280-26-044263
Boardroom Alpha · Filing insights

Sionna elected four Class II directors to 2029 and ratified Deloitte as auditor for 2026.

About Sionna Therapeutics Inc
Market cap
$274M
1Y TSR
−7.3%
Board grade
C-
Sector
Healthcare
CEO
Michael Cloonan
Last annual meeting: Jun 17, 2026 · View full Sionna Therapeutics Inc profile →
sion-20260617

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
__________________________
FORM 8-K
__________________________
CURRENT REPORT
Pursuant to Section 13 or 15(d)
of the Securities Exchange Act of 1934
Date of Report (date of earliest event reported): June 17, 2026
__________________________
SIONNA THERAPEUTICS, INC.
(Exact name of registrant as specified in its charter)
__________________________
Delaware001-4250484-2801521
(State or other jurisdiction
of incorporation)
(Commission
File Number)
(I.R.S. Employer
Identification No.)
SIONNA THERAPEUTICS, INC.
21 Hickory Drive, Suite 500
Waltham, MA02451
(Address of principal executive offices, including zip code)
617-819-2020
(Registrant’s telephone number, including area code)
Not Applicable
(Former Name or Former Address, if Changed Since Last Report)
__________________________
Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:
Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))
Securities registered pursuant to Section 12(b) of the Act:
Title of each classTrading
Symbol(s)
Name of each exchange
on which registered
Common Stock, $0.001 par value per shareSIONThe Nasdaq Global Market
Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).
Emerging growth company x
If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. o



Item 5.07    Submission of Matters to a Vote of Security Holders.
On June 17, 2026, Sionna Therapeutics, Inc. (the "Company") held its Annual Meeting of Stockholders, at which a quorum was present. There were 45,142,330 shares of the Company's common stock outstanding as of the record date of April 21, 2026.
The following are the voting results for the proposals considered and voted upon at the meeting, which are described in detail in the Company's Definitive Proxy Statement filed with the Securities and Exchange Commission on April 27, 2026.
1.To elect four nominees as Class II directors: H. Edward Fleming, Jr., M.D., Marcella Kuhlman Ruddy, M.D., Peter A. Thompson, M.D., and Joanne Louise Viney, Ph.D., each to hold office until the Company's Annual Meeting of Stockholders in 2029.
NomineeVotes ForVotes WithheldBroker Non-Votes
H. Edward Fleming, Jr.42,168,56940,0211,084,330
Marcella Kuhlman Ruddy40,270,2791,938,3111,084,330
Peter A. Thompson39,862,1852,346,4051,084,330
Joanne Louise Viney41,931,706276,8841,084,330
2.To ratify the appointment of Deloitte & Touche LLP as the Company's independent registered public accounting firm for the fiscal year ending December 31, 2026.
Votes ForVotes AgainstAbstentions
43,291,2151,198507
Based on the foregoing votes, each of the nominees was elected as a Class II director and the appointment of Deloitte & Touche LLP was ratified.



SIGNATURE
Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.
Sionna Therapeutics, Inc.
Date: June 18, 2026By:/s/ Jennifer Fitzpatrick
Name:Jennifer Fitzpatrick
Title:Chief Legal Officer

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Reference

Frequently asked questions

When did Sionna Therapeutics Inc file this 8-K?
Sionna Therapeutics Inc (SION) filed this Current Report (Form 8-K) with the SEC on June 18, 2026. The accession number assigned by EDGAR is 0001628280-26-044263.
What does an 8-K disclose?
Form 8-K is the SEC's current-report form, used to disclose material events between periodic reports (10-K / 10-Q). Triggers include CEO/CFO departures, acquisitions, bankruptcies, earnings releases, auditor changes, changes in fiscal year, and amendments to corporate governance. Each 8-K is keyed to one or more Item numbers (1.01 through 9.01).
What is the key takeaway from this filing?
Sionna elected four Class II directors to 2029 and ratified Deloitte as auditor for 2026. This is Boardroom Alpha's one-line summary of the current report; see the full filing text above for the formal disclosure.
What Item codes does an 8-K cover?
An 8-K's Item codes (1.01 through 9.01) specify what kind of event is being disclosed — e.g. Item 1.01 for entering a material agreement, Item 5.02 for departure/election of directors and executive officers, Item 8.01 for other events. The Item codes for this 8-K appear in the filing text above.
Where can I find Sionna Therapeutics Inc's prior current reports on EDGAR?
The SEC EDGAR browser lists every 8-K Sionna Therapeutics Inc has filed under CIK 2036042, sortable by date. Use the "View on SEC EDGAR" link in the page header, or browse directly via https://www.sec.gov/cgi-bin/browse-edgar.
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