Offerings // SYNLOGIC, INC.

SYBX offering history

Every offering-related filing in SYNLOGIC, INC.’s recent SEC record — registrations (announced capacity) kept separate from pricing documents (executed sales). Reviewed 626 filings back to Aug 23, 2011.

Last executed offering

Oct 2, 2023

424B4 — priced deal (shares or notes)

Last registration (announced)

Aug 15, 2025

S-3/A — capacity, not a sale

Executed, last 12 months

424B pricings + 8-K 3.02 sales

Registered, last 12 months

S-1/S-3/F-series registrations

Date	Filing		What it means
Aug 20, 2025	EFFECT →	EFFECTIVE	SEC declared a registration effective — selling can begin
Aug 15, 2025	S-3/A →	REGISTERED	S-3/A registration — capacity to sell shares, not a sale yet
Aug 8, 2025	S-3 →	REGISTERED	S-3 registration — capacity to sell shares, not a sale yet
Oct 2, 2023	424B4 →	EXECUTED	Final prospectus — offering priced (typical for IPOs and marketed share deals)
Sep 28, 2023	S-1/A →	REGISTERED	S-1/A registration — capacity to sell shares, not a sale yet
Sep 28, 2023	S-1MEF →	REGISTERED	S-1MEF registration — capacity to sell shares, not a sale yet
Sep 28, 2023	EFFECT →	EFFECTIVE	SEC declared a registration effective — selling can begin
Sep 27, 2023	S-1/A →	REGISTERED	S-1/A registration — capacity to sell shares, not a sale yet
Sep 8, 2023	S-1 →	REGISTERED	S-1 registration — capacity to sell shares, not a sale yet
Apr 4, 2023	424B5 →	EXECUTED	Shelf takedown priced — shares or notes (small-caps: usually shares; open the filing to confirm)
Sep 23, 2021	424B5 →	EXECUTED	Shelf takedown priced — shares or notes (small-caps: usually shares; open the filing to confirm)
Sep 22, 2021	424B5 →	EXECUTED	Shelf takedown priced — shares or notes (small-caps: usually shares; open the filing to confirm)
Jul 30, 2021	EFFECT →	EFFECTIVE	SEC declared a registration effective — selling can begin
Jul 23, 2021	S-3 →	REGISTERED	S-3 registration — capacity to sell shares, not a sale yet
Apr 19, 2021	424B5 →	EXECUTED	Shelf takedown priced — shares or notes (small-caps: usually shares; open the filing to confirm)
Apr 15, 2021	424B5 →	EXECUTED	Shelf takedown priced — shares or notes (small-caps: usually shares; open the filing to confirm)
Feb 10, 2021	424B5 →	EXECUTED	Shelf takedown priced — shares or notes (small-caps: usually shares; open the filing to confirm)
Mar 18, 2020	424B5 →	EXECUTED	Shelf takedown priced — shares or notes (small-caps: usually shares; open the filing to confirm)
Sep 17, 2019	424B3 →	UPDATE	Prospectus update — often a resale registration, not necessarily new capital
Sep 13, 2019	EFFECT →	EFFECTIVE	SEC declared a registration effective — selling can begin
Aug 30, 2019	S-3/A →	REGISTERED	S-3/A registration — capacity to sell shares, not a sale yet
Aug 8, 2019	S-3 →	REGISTERED	S-3 registration — capacity to sell shares, not a sale yet
Jun 12, 2019	8-K →	EXECUTED	Unregistered share sale disclosed (8-K item 3.02)
Aug 30, 2018	EFFECT →	EFFECTIVE	SEC declared a registration effective — selling can begin
Aug 23, 2018	S-3/A →	REGISTERED	S-3/A registration — capacity to sell shares, not a sale yet
Aug 9, 2018	S-3 →	REGISTERED	S-3 registration — capacity to sell shares, not a sale yet
Apr 6, 2018	424B5 →	EXECUTED	Shelf takedown priced — shares or notes (small-caps: usually shares; open the filing to confirm)
Jan 25, 2018	424B5 →	EXECUTED	Shelf takedown priced — shares or notes (small-caps: usually shares; open the filing to confirm)
Jan 23, 2018	424B5 →	EXECUTED	Shelf takedown priced — shares or notes (small-caps: usually shares; open the filing to confirm)
Oct 25, 2017	EFFECT →	EFFECTIVE	SEC declared a registration effective — selling can begin
Oct 13, 2017	S-3 →	REGISTERED	S-3 registration — capacity to sell shares, not a sale yet
Jul 13, 2017	424B3 →	UPDATE	Prospectus update — often a resale registration, not necessarily new capital
Jul 13, 2017	EFFECT →	EFFECTIVE	SEC declared a registration effective — selling can begin
Oct 1, 2015	424B4 →	EXECUTED	Final prospectus — offering priced (typical for IPOs and marketed share deals)
Sep 30, 2015	S-1/A →	REGISTERED	S-1/A registration — capacity to sell shares, not a sale yet
Sep 30, 2015	FWP →	MARKETING	Free-writing prospectus — offering being marketed
Sep 30, 2015	EFFECT →	EFFECTIVE	SEC declared a registration effective — selling can begin
Sep 29, 2015	S-1/A →	REGISTERED	S-1/A registration — capacity to sell shares, not a sale yet
Sep 25, 2015	S-1/A →	REGISTERED	S-1/A registration — capacity to sell shares, not a sale yet
Sep 18, 2015	S-1/A →	REGISTERED	S-1/A registration — capacity to sell shares, not a sale yet

SYBX offering-related filings from SEC EDGAR, newest first (capped at 40). Each links to the original document.

Two honest limits. (1) A 424B takedown can price shares or notes — EDGAR’s metadata doesn’t say which, so open the document: large investment-grade filers use these mostly for bond deals (no dilution), small-caps mostly for shares. (2) At-the-market (ATM) programs sell shares gradually and individual sales are not separately filed — the visible footprint is the enabling shelf and its 424B5; actual ATM share counts surface later in the 10-Q/10-K share count. Educational information from public filings, not investment advice.

Is a shelf active now? →Do they need money? →Red flags →Full SYBX workspace →

SYBX offering FAQ

When did SYBX last execute an offering?

Per SEC filings, SYNLOGIC, INC.'s most recent priced offering document is a 424B4 filed 2023-10-02. Note a 424B takedown can price shares or notes (debt) — the linked document says which.

When did SYBX last announce or register an offering?

The most recent registration is a S-3/A filed 2025-08-15. A registration is capacity to sell shares — not a sale.

Does an offering always mean dilution?

Registered direct offerings and shelf takedowns issue new shares and dilute existing holders. Resale registrations (424B3/B7) let existing holders sell and do not create new shares. Secondary sales by insiders also do not dilute. Each row here is labeled with what it is.

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