Atlas Venture Fund XI, L.P. - Feb 6, 2025 Form 3 Insider Report for Sionna Therapeutics, Inc. (SION)

Role: 10%+ Owner
Signature: Atlas Venture Fund XI, L.P., By: Atlas Venture Associates XI, L.P., its general partner, by Atlas Venture Associates XI, LLC, its general partner, By: /s/ Ommer Chohan, Chief Financial Officer
Stock symbol: SION
Transactions as of: Feb 6, 2025
Transactions value $: $0
Form type: 3
Date filed: 2/6/2025, 09:12 PM
Previous filing: Nov 5, 2024
Next filing: Feb 10, 2025
SEC: View on sec.gov

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
holding	SION	Series Seed convertible preferred stock							Feb 6, 2025	Common Stock	719K		Direct	F1, F2
holding	SION	Series A convertible preferred stock							Feb 6, 2025	Common Stock	1.24M		Direct	F1, F2
holding	SION	Series B convertible preferred stock							Feb 6, 2025	Common Stock	889K		Direct	F1, F2
holding	SION	Series C convertible preferred stock							Feb 6, 2025	Common Stock	42.1K		Direct	F1, F2
holding	SION	Series C convertible preferred stock							Feb 6, 2025	Common Stock	748K		By Atlas Venture Opportunity Fund II, L.P.	F1, F3

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	Each share of Series Seed convertible preferred stock, Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") is convertible into Common Stock on a one-for-1.4611 basis at the option of the holder, and will convert automatically upon the closing of the Issuer's initial public offering into the number of shares shown in column 3 without payment of consideration. The Preferred Stock has no expiration date.
F2	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. Each of AVA XI LP and AVA XI LLC disclaims Section 16 beneficial ownership of the securities held by AVF XI, except to the extent of its pecuniary interest therein, if any.
F3	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. Each of AVAO II LP and AVAO II LLC disclaims Section 16 beneficial ownership of the securities held by AVOF II, except to the extent of its pecuniary interest therein, if any.