Offerings // Seres Therapeutics, Inc.

MCRB offering history

Every offering-related filing in Seres Therapeutics, Inc.’s recent SEC record — registrations (announced capacity) kept separate from pricing documents (executed sales). Reviewed 716 filings back to Jun 9, 2014.

Last executed offering

Aug 4, 2026

424B5 — priced deal (shares or notes)

Last registration (announced)

Aug 13, 2026

S-3 — 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 13, 2026	S-3 →	REGISTERED	S-3 registration — capacity to sell shares, not a sale yet
Aug 4, 2026	424B5 →	EXECUTED	Shelf takedown priced — shares or notes (small-caps: usually shares; open the filing to confirm)
Oct 11, 2024	424B3 →	UPDATE	Prospectus update — often a resale registration, not necessarily new capital
Oct 11, 2024	EFFECT →	EFFECTIVE	SEC declared a registration effective — selling can begin
Oct 1, 2024	8-K →	EXECUTED	Unregistered share sale disclosed (8-K item 3.02)
Oct 1, 2024	S-3 →	REGISTERED	S-3 registration — capacity to sell shares, not a sale yet
Aug 6, 2024	8-K →	EXECUTED	Unregistered share sale disclosed (8-K item 3.02)
Aug 15, 2023	EFFECT →	EFFECTIVE	SEC declared a registration effective — selling can begin
Aug 8, 2023	S-3 →	REGISTERED	S-3 registration — capacity to sell shares, not a sale yet
Apr 27, 2023	8-K →	EXECUTED	Unregistered share sale disclosed (8-K item 3.02)
Jun 30, 2022	424B5 →	EXECUTED	Shelf takedown priced — shares or notes (small-caps: usually shares; open the filing to confirm)
May 6, 2022	EFFECT →	EFFECTIVE	SEC declared a registration effective — selling can begin
May 21, 2021	424B5 →	EXECUTED	Shelf takedown priced — shares or notes (small-caps: usually shares; open the filing to confirm)
Aug 17, 2020	FWP →	MARKETING	Free-writing prospectus — offering being marketed
Aug 14, 2020	424B5 →	EXECUTED	Shelf takedown priced — shares or notes (small-caps: usually shares; open the filing to confirm)
Aug 14, 2020	424B5 →	EXECUTED	Shelf takedown priced — shares or notes (small-caps: usually shares; open the filing to confirm)
Aug 13, 2020	FWP →	MARKETING	Free-writing prospectus — offering being marketed
Aug 13, 2020	FWP →	MARKETING	Free-writing prospectus — offering being marketed
Aug 11, 2020	S-3ASR →	REGISTERED	Automatic shelf registration — effective immediately (large filers)
Aug 11, 2020	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)
Mar 18, 2020	EFFECT →	EFFECTIVE	SEC declared a registration effective — selling can begin
Mar 9, 2020	S-3 →	REGISTERED	S-3 registration — capacity to sell shares, not a sale yet
Nov 27, 2019	424B5 →	EXECUTED	Shelf takedown priced — shares or notes (small-caps: usually shares; open the filing to confirm)
Jun 14, 2019	424B5 →	EXECUTED	Shelf takedown priced — shares or notes (small-caps: usually shares; open the filing to confirm)
Jun 12, 2019	424B5 →	EXECUTED	Shelf takedown priced — shares or notes (small-caps: usually shares; open the filing to confirm)
Mar 24, 2017	EFFECT →	EFFECTIVE	SEC declared a registration effective — selling can begin
Mar 16, 2017	S-3 →	REGISTERED	S-3 registration — capacity to sell shares, not a sale yet
Jun 26, 2015	424B4 →	EXECUTED	Final prospectus — offering priced (typical for IPOs and marketed share deals)
Jun 25, 2015	S-1MEF →	REGISTERED	S-1MEF registration — capacity to sell shares, not a sale yet
Jun 25, 2015	EFFECT →	EFFECTIVE	SEC declared a registration effective — selling can begin
Jun 24, 2015	S-1/A →	REGISTERED	S-1/A registration — capacity to sell shares, not a sale yet
Jun 16, 2015	S-1/A →	REGISTERED	S-1/A registration — capacity to sell shares, not a sale yet
May 27, 2015	S-1 →	REGISTERED	S-1 registration — capacity to sell shares, not a sale yet

MCRB 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 MCRB workspace →

MCRB offering FAQ

When did MCRB last execute an offering?

Per SEC filings, Seres Therapeutics, Inc.'s most recent priced offering document is a 424B5 filed 2026-08-04. Note a 424B takedown can price shares or notes (debt) — the linked document says which.

When did MCRB last announce or register an offering?

The most recent registration is a S-3 filed 2026-08-13. 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.