The Sionna Therapeutics, Inc. (Nasdaq: SION) SEC filings page on Stock Titan provides access to the company’s regulatory disclosures as filed with the U.S. Securities and Exchange Commission. Sionna describes itself as a clinical-stage biopharmaceutical company focused on developing CFTR-targeted therapies for cystic fibrosis, and its filings offer detail on this business and its financial position.
Among the key documents available are current reports on Form 8-K, where Sionna furnishes press releases announcing quarterly financial results and business highlights. For example, the company has used Form 8-K to present information on research and development expenses, general and administrative expenses, net loss, cash and cash equivalents, and progress across its clinical pipeline of NBD1 stabilizers and complementary CFTR modulators.
In addition to 8-Ks, investors typically look to annual reports on Form 10-K and quarterly reports on Form 10-Q for broader discussions of risk factors, research and development activities, and the company’s focus on cystic fibrosis therapies. These filings can also describe Sionna’s status as an emerging growth company, its operating segment dedicated to CF drug development, and other structural aspects of the business.
Stock Titan enhances access to SION filings by pairing real-time updates from the EDGAR system with AI-powered summaries that explain the significance of each document in clear language. Users can quickly identify items related to clinical trial progress, financial condition, and other material events, and can review insider and management-related disclosures where applicable. This page serves as a central location for reviewing Sionna’s regulatory history and understanding how its CF-focused strategy is reflected in formal SEC documents.
Sionna Therapeutics, Inc. (SION) is the subject of an amended Schedule 13D/A from the RA Capital group updating their ownership position. RA Capital Management, L.P., together with related funds and accounts, reports beneficial ownership of 6,476,193 shares of common stock, representing 14.3% of the outstanding shares, based on 45,212,399 shares outstanding as of July 31, 2026.
The position is held across RA Capital Healthcare Fund, L.P., RA Capital Nexus Fund, L.P., RA Capital Nexus Fund III, L.P., a separately managed account, and vested stock options held by Dr. Joshua Resnick for RA Capital’s benefit. RA Capital has delegated voting and investment authority over these holdings and may be deemed the beneficial owner for Section 13(d) purposes, while various entities and individuals expressly disclaim beneficial ownership beyond regulatory reporting. On September 17, 2026, RA Capital Healthcare Fund, L.P. reported selling 3,415,011 shares in a block sale at $6.32 per share and 33,800 shares in open-market trades at a weighted average price of $7.46. RA Capital Nexus Fund III, L.P. had previously fallen below 5% ownership on November 17, 2025.
Sionna Therapeutics, Inc. (SION) had large shareholder entities affiliated with RA Capital report open-market sales of its common stock on September 17, 2026. RA Capital Healthcare Fund LP sold 3,415,011 shares at $6.32 per share and a further 33,800 shares at a weighted average price of $7.46 per share, in multiple trades between $7.30 and $7.68. The transactions were reported as indirectly held and the RA Capital adviser, its general partner and principals Peter Kolchinsky and Rajeev Shah disclaim beneficial ownership except to the extent of their pecuniary interest. No Rule 10b5-1 trading plan is reported.
Sionna Therapeutics, Inc. reported equity compensation changes for its CFO and CBO, Elena Ridloff. On September 17, 2026, she received a non-qualified stock option for 165,440 shares of common stock at an exercise price of $7.18 per share, reflecting an option repricing that replaced a prior option over the same number of shares with a $39.21 exercise price. She was also granted 47,269 time-based RSUs vesting on June 17, 2027 and 47,268 performance-based RSUs that vest upon achievement of a designated performance milestone, in each case subject to continued service.
Sionna Therapeutics, Inc. (SION) reported that its CMO and Head of R&D, Charlotte McKee, received equity awards and an option repricing on September 17, 2026. She was granted 100,000 RSUs, split between time-based and performance-based vesting, and an existing stock option for 155,700 shares was repriced to an exercise price of $7.18 per share, replacing an option with an exercise price of $39.21 per share. The repriced option and RSUs are issued under the company’s 2025 Stock Option and Incentive Plan and remain subject to service-based vesting and, for part of the RSUs, achievement of a performance milestone. No Rule 10b5-1 trading plan is reported.
Sionna Therapeutics, Inc. (SION) reported equity compensation changes for its CLO and Head of Program Mgmt., Jennifer Fitzpatrick, on September 17, 2026. A stock option for 103,140 shares with a prior exercise price of $39.21 was repriced to $7.18, with all other terms unchanged. Fitzpatrick also received two grants of restricted stock units totaling 56,265 RSUs, half time-based vesting on June 17, 2027 and half vesting upon achievement of a performance milestone, all subject to continued service.
Sionna Therapeutics, Inc. (SION) reported that President & CEO Michael Cloonan received equity awards and an option repricing on September 17, 2026. He was granted 218,050 shares of Common Stock in the form of restricted stock units, split evenly between time-based vesting on June 17, 2027 and performance-based vesting upon a designated milestone. On the same date, a non-qualified stock option for 436,100 shares was repriced to have an exercise price of $7.18 per share, replacing an option with a $39.21 exercise price, with all other terms unchanged and subject to a retention period and prior vesting conditions.
Sionna Therapeutics, Inc. (SION) received a notice that RA Capital Healthcare Fund, L.P. intends to sell common stock under Rule 144 through Goldman Sachs & Co. The notice covers 3,448,811 shares of common stock, with an aggregate market value of $21,834,318, to be sold on or about September 17, 2026 on Nasdaq.
The fund previously acquired Sionna common shares in private transactions dated February 2, 2022 (606,502 shares) and March 4, 2024 (1,819,723 shares), and in the initial public offering dated February 7, 2025 (1,022,586 shares). Sionna reports 45,212,399 common shares outstanding in connection with this notice.
Sionna Therapeutics, Inc. (SION) approved a major restructuring to concentrate resources on its SION-451 and SION-2222 dual combination cystic fibrosis program and to extend its cash runway. The plan includes reducing the workforce by approximately 46% and winding down the SION-719 add-on program, including related clinical and manufacturing contracts.
Sionna estimates approximately $6.4 million in restructuring and related charges, primarily severance and contract close-out costs, with activities largely completed by the end of the third quarter of 2026 and cash payments continuing into the fourth quarter of 2026. The Chief Business Officer, Caroline Stark Beer, will depart effective September 15, 2026, and existing executives will assume expanded roles without compensation changes. The Board also approved a stock option repricing effective September 17, 2026, lowering exercise prices of certain employee options to the stock’s closing price on the repricing date, subject to an 18‑month retention period. Sionna plans to initiate the AscenSION CF Phase 2a proof‑of‑concept trial of SION-451 + SION-2222 in the first quarter of 2027 and, based on its cash of $268.3 million at the end of Q2 2026 and cost-saving measures, estimates its cash runway extends into the second half of 2029.
Sionna Therapeutics, Inc. reported topline results from two cystic fibrosis programs and outlined strategic changes. The Phase 2a PreciSION CF proof-of-concept trial of SION-719, added to Trikafta in people with cystic fibrosis, did not achieve the key activity endpoint of sweat chloride reduction, and the company is not advancing SION-719 as an add-on to standard of care. Potential confounders in this trial are being evaluated to guide next steps for the SION-451 dual combination program, which has completed a Phase 1 healthy volunteer trial with dual combinations involving SION-2222 and SION-109. Sionna ended Q2 with approximately $268.3 million in cash, cash equivalents, and marketable securities and plans to take actions to preserve capital while assessing future development plans.
Sionna Therapeutics, Inc. is a clinical-stage biopharmaceutical company focused on cystic fibrosis, developing NBD1 stabilizers and complementary CFTR modulators. It reported a net loss of $56.7 million for the six months ended June 30, 2026, compared with $34.6 million a year earlier, as R&D and G&A spending increased with pipeline advancement.
Research and development expenses rose to $40.8 million and general and administrative costs to $21.2 million. Cash, cash equivalents and marketable securities totaled $268.3 million, which management expects will fund operations into 2028. Sionna also has an unused $250.0 million at-the-market equity facility and is progressing a Phase 2a trial of SION-719 and a Phase 1 dual-combination trial of SION-451 with complementary modulators.