| Name | Relationship | Address | Signature | Signature date | CIK |
|---|---|---|---|---|---|
| Booth Bruce | Director | C/O SIONNA THERAPEUTICS, INC., 21 HICKORY DRIVE, SUITE 500, WALTHAM | /s/ Ommer Chohan, Attorney-in-Fact | 20 Oct 2025 | 0001451612 |
| Type | Sym | Class | Transaction | Value $ | Shares | Change % | * Price $ | Shares After | Date | Ownership | Footnotes |
|---|---|---|---|---|---|---|---|---|---|---|---|
| transaction | SION | Common Stock | Sale | $259,169 | -8,596 | -0.33% | $30.15 | 2,610,589 | 16 Oct 2025 | By Atlas Venture Fund XI, L.P. | F1, F2, F3 |
| transaction | SION | Common Stock | Sale | $54,391 | -1,804 | -0.24% | $30.15 | 749,860 | 16 Oct 2025 | By Atlas Venture Opportunity Fund II, L.P. | F2, F4, F5 |
| transaction | SION | Common Stock | Sale | $1,429,758 | -45,117 | -1.7% | $31.69 | 2,565,472 | 16 Oct 2025 | By Atlas Venture Fund XI, L.P. | F1, F3, F6 |
| transaction | SION | Common Stock | Sale | $300,104 | -9,470 | -1.3% | $31.69 | 740,390 | 16 Oct 2025 | By Atlas Venture Opportunity Fund II, L.P. | F4, F5, F6 |
| transaction | SION | Common Stock | Sale | $2,407,041 | -73,296 | -2.9% | $32.84 | 2,492,176 | 16 Oct 2025 | By Atlas Venture Fund XI, L.P. | F1, F3, F7 |
| transaction | SION | Common Stock | Sale | $505,211 | -15,384 | -2.1% | $32.84 | 725,006 | 16 Oct 2025 | By Atlas Venture Opportunity Fund II, L.P. | F4, F5, F7 |
| transaction | SION | Common Stock | Sale | $430,201 | -12,888 | -0.52% | $33.38 | 2,479,288 | 16 Oct 2025 | By Atlas Venture Fund XI, L.P. | F1, F3, F8 |
| transaction | SION | Common Stock | Sale | $90,293 | -2,705 | -0.37% | $33.38 | 722,301 | 16 Oct 2025 | By Atlas Venture Opportunity Fund II, L.P. | F4, F5, F8 |
| transaction | SION | Common Stock | Sale | $925,154 | -28,821 | -1.2% | $32.10 | 2,450,467 | 17 Oct 2025 | By Atlas Venture Fund XI, L.P. | F1, F3, F9 |
| transaction | SION | Common Stock | Sale | $194,173 | -6,049 | -0.84% | $32.10 | 716,252 | 17 Oct 2025 | By Atlas Venture Opportunity Fund II, L.P. | F4, F5, F9 |
| transaction | SION | Common Stock | Sale | $701,662 | -21,451 | -0.88% | $32.71 | 2,429,016 | 17 Oct 2025 | By Atlas Venture Fund XI, L.P. | F1, F3, F10 |
| transaction | SION | Common Stock | Sale | $147,293 | -4,503 | -0.63% | $32.71 | 711,749 | 17 Oct 2025 | By Atlas Venture Opportunity Fund II, L.P. | F4, F5, F10 |
| transaction | SION | Common Stock | Sale | $8,301 | -248 | -0.01% | $33.47 | 2,428,768 | 17 Oct 2025 | By Atlas Venture Fund XI, L.P. | F1, F3, F11 |
| transaction | SION | Common Stock | Sale | $1,740 | -52 | -0.01% | $33.47 | 711,697 | 17 Oct 2025 | By Atlas Venture Opportunity Fund II, L.P. | F4, F5, F11 |
| transaction | SION | Common Stock | Sale | $651,218 | -20,485 | -0.84% | $31.79 | 2,408,283 | 20 Oct 2025 | By Atlas Venture Fund XI, L.P. | F1, F3, F12 |
| transaction | SION | Common Stock | Sale | $136,697 | -4,300 | -0.6% | $31.79 | 707,397 | 20 Oct 2025 | By Atlas Venture Opportunity Fund II, L.P. | F4, F5, F12 |
| transaction | SION | Common Stock | Sale | $833,726 | -25,788 | -1.1% | $32.33 | 2,382,495 | 20 Oct 2025 | By Atlas Venture Fund XI, L.P. | F1, F3, F13 |
| transaction | SION | Common Stock | Sale | $174,970 | -5,412 | -0.77% | $32.33 | 701,985 | 20 Oct 2025 | By Atlas Venture Opportunity Fund II, L.P. | F4, F5, F13 |
Buy Plan / Sale Plan: These are also open market purchases/sales of shares, but in this case the transaction is part of a trading plan. Rule 10b5-1 allows insiders to setup a trading plan to buy/sell stocks over a certain period of time. Since the purchases/sales are predetermined, this protects the insiders from violating insider trading law.
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).
| Id | Content |
|---|---|
| F1 | This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by Atlas Venture Fund XI, L.P. on February 25, 2025. |
| F2 | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $30.14 to $30.74 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 ranges set forth in footnotes (2), (6), (7), (8), (9), (10), (11), (12) and (13). |
| F3 | These shares are held directly by Atlas Venture Fund XI, L.P. ("AVF XI "). The general partner of AVF XI is Atlas Venture Associates XI, L.P. ("AVA XI LP"). Atlas Venture Associates XI, LLC ("AVA XI LLC") is the general partner of AVA XI LP. The Reporting Person is a member of AVA XI LLC and disclaims beneficial ownership of such securities held by AVF XI, except to the extent of his pecuniary interest therein, if any. |
| F4 | This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by Atlas Venture Opportunity Fund II, L.P. on February 25, 2025. |
| F5 | These shares are held directly by Atlas Venture Opportunity Fund II, L.P. ("AVOF II"). The general partner of AVOF II is Atlas Venture Associates Opportunity II, L.P. ("AVAO II LP"). Atlas Venture Associates Opportunity II, LLC ("AVAO II LLC") is the general partner of AVAO II LP. The Reporting Person is a member of AVAO II LLC and disclaims beneficial ownership of such securities held by AVOF II, except to the extent of his pecuniary interest therein, if any. |
| F6 | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $31.21 to $32.205 inclusive. |
| F7 | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $32.21 to $33.205 inclusive. |
| F8 | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $33.21 to $33.86 inclusive. |
| F9 | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $31.325 to $32.32 inclusive. |
| F10 | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $32.335 to $33.25 inclusive. |
| F11 | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $33.47 to $33.475 inclusive. |
| F12 | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $31.06 to $32.05 inclusive. |
| F13 | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $32.06 to $32.59 inclusive. |