Sionna Therapeutics SEC Filings

Sionna Therapeutics (SION) insider sale notice: This Form 144 reports a proposed sale of 25,000 common shares by an insider through Morgan Stanley Smith Barney, valued at $687,500, with the sale target date of 09/26/2025 on NASDAQ. The securities were acquired on 09/26/2025 by exercise of stock options and paid in cash. The filing shows 44,139,823 shares outstanding, so the proposed sale equals approximately 0.0566% of outstanding shares. The filer also disclosed three 10b5-1 sales by Michael Cloonan in August 2025 totaling 50,000 shares for aggregate gross proceeds of $1,193,154.98. The notice includes the standard insider representation about absence of undisclosed material information and a 10b5-1 plan reference but does not provide plan adoption dates or signature details.

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.

Sionna Therapeutics, Inc. (SION) filing a Form 144 notifies a proposed sale of 10,250 common shares via Morgan Stanley Smith Barney on NASDAQ with an aggregate market value of $251,637.50. The shares were acquired and paid for on 09/04/2025 through exercise of stock options from the issuer. The filing lists 44,139,823 shares outstanding and reports no other sales by the seller in the past three months. The filer certifies no undisclosed material adverse information.

Elena Ridloff, CFO & Head of Corporate Development of Sionna Therapeutics (SION), reported planned sales under a Rule 10b5-1 trading plan adopted May 20, 2025. The Form 4 shows sales executed on 08/29/2025 (748 shares) and 09/02/2025 (8,836 shares) at weighted-average prices of $25.18 and $25.08 respectively, for a total of 9,584 shares sold. After the 08/29 sale Ridloff held 47,368 shares; after the 09/02 sale she held 38,532 shares. The filings state the trades were automatic under the 10b5-1 plan and note the sales occurred in multiple transactions at prices within the disclosed ranges. The reporting person authorized Jennifer Fitzpatrick as attorney-in-fact to sign the Form.

Sionna Therapeutics director and CEO Michael Cloonan reported option exercises and sales executed under a Rule 10b5-1 plan. On 08/26/2025 and 08/27/2025 he exercised options with a $6.11 exercise price covering 17,574 and 7,426 shares respectively. Those exercises increased exercisable option counts and were followed by sales of the same share amounts at weighted-average prices of $24.96 and $25.0086, reducing his direct holdings to 547,343 shares. The Form 4 notes the 10b5-1 plan was adopted May 21, 2025, and the underlying options vest monthly through March 1, 2032.

Elena Ridloff, CFO & Head of Corporate Development of Sionna Therapeutics, Inc. (SION), reported sales of common stock on August 26-28, 2025 under a Rule 10b5-1 trading plan adopted May 20, 2025. The filings show sales of 3,700 shares on 08/26 at a weighted-average price of $25.13 (prices ranged $25.00–$25.28), 3,618 shares on 08/27 at $25.10 (range $25.00–$25.32), and 16,098 shares on 08/28 at $25.97 (range $25.01–$26.41). Post-transaction beneficial ownership is reported as 67,832 shares after 08/26, 64,214 after 08/27, and 48,116 after 08/28. The Form 4 was submitted by one reporting person and signed by an attorney-in-fact on 08/28/2025.

Sionna Therapeutics (SION) Form 144 shows a proposed sale of 25,000 common shares through Morgan Stanley Smith Barney LLC with an aggregate market value of $601,500. The securities were acquired and are scheduled for sale on 08/26/2025 following an exercise of stock options paid in cash. The filing also records a prior Rule 10b5-1 sale of 25,000 shares on 08/20/2025 that generated $568,715 in gross proceeds. The filing lists total shares outstanding as 44,139,823. The notice includes the standard attestation that the seller does not possess undisclosed material adverse information and references reliance on a 10b5-1 plan where applicable.

Sionna Therapeutics (SION) Form 144 notice reports a proposed sale of 33,000 shares of common stock through Morgan Stanley Smith Barney, with an aggregate market value of $793,980 and an approximate sale date of 08/26/2025 on NASDAQ. The shares were acquired on 06/15/2023 upon exercise of stock options and paid in cash. The filer also disclosed recent Rule 10b5-1 sales by the same account: 17,500 shares sold on 08/20/2025 for $397,152 and 34,500 shares sold on 08/19/2025 for $727,112.80. The filing includes the standard representation that the seller is not aware of undisclosed material adverse information and references a possible 10b5-1 plan adoption date field (not populated in the text provided).

Michael Cloonan, President & CEO and Director of Sionna Therapeutics (SION), reported transactions on 08/20/2025 executed under a Rule 10b5-1 plan. On that date he exercised a non-qualified stock option to acquire 25,000 shares at $6.11 per share, increasing his option-derived common stock to 25,000 shares exercisable and leaving him with 572,343 shares beneficially owned immediately after the acquisition. The option vests monthly in 48 installments following 02/02/2022 and has an expiration in 2032.

Simultaneously, Mr. Cloonan sold 25,000 common shares in multiple transactions at a weighted average price of $22.75 per share (individual sale prices ranged $21.07 to $23.99). After the sale his reported beneficial ownership was 547,343 shares. The filing states these trades were made pursuant to the 10b5-1 plan adopted 05/21/2025 and was signed via attorney-in-fact on 08/21/2025.