What SEC filings does Seres Therapeutics, Inc. submit to the SEC?

Seres Therapeutics, Inc. (MCRB) submits several types of SEC filings including Form 4 (insider transactions), Form 144 (proposed insider sales), 8-K reports (material events such as earnings releases, acquisitions, leadership changes), and periodic reports — the 10-Q (quarterly) and 10-K (annual). All filings are publicly available through SEC EDGAR.

What does a Form 4 filing tell me about MCRB?

A Form 4 for MCRB discloses a transaction by a company insider — typically a director, officer, or 10%+ shareholder. It shows the source-reported date, number of shares, price, and updated ownership. These facts do not establish motive or predict future returns.

How do I interpret an 8-K filing from Seres Therapeutics, Inc.?

An 8-K signals a material event requiring prompt disclosure. Common triggers include earnings pre-announcements, acquisitions, leadership appointments or departures, credit changes, or regulatory actions. Read the item codes inside the filing to understand exactly what was disclosed before drawing conclusions.

What is the difference between a 10-K and 10-Q for MCRB?

The 10-K is Seres Therapeutics, Inc.'s annual report with fully audited financial statements, comprehensive MD&A, and complete risk factor disclosures — filed 60–90 days after fiscal year-end. The 10-Q is a lighter quarterly report with unaudited financials filed for the first three quarters. Together they provide a continuous financial picture of the company.

Where can I see all MCRB SEC filings directly on EDGAR?

You can view all historical Seres Therapeutics, Inc. filings on the SEC EDGAR company page for MCRB. Each filing card on this page links directly to the original SEC document.

How often does Seres Therapeutics, Inc. file with the SEC?

Seres Therapeutics, Inc. files one 10-K per year and up to three 10-Qs per year. Form 4 insider transactions must be reported within two business days of each trade, so the frequency depends on how often insiders are buying or selling MCRB shares. 8-K filings occur whenever a material event happens — which can be several times per quarter for an active company.

MCRB SEC Filing News — Seres Therapeutics, Inc.

Latest SEC filings for Seres Therapeutics, Inc. (MCRB) explained in plain English. Covers insider buying and selling (Form 4), proposed insider sales (Form 144), material company events (8-K), and quarterly & annual reports (10-Q / 10-K). StrongBuyAnalytics provides navigation and brief excerpts or summaries; original filings remain at the SEC/source links and were authored by their filers, not StrongBuyAnalytics. Filing dates shown are source dates. Coverage and detection can be delayed or incomplete because of SEC availability, amendments, parsing, caching, or outages. Latest source filing date shown: 2026-08-18.

Seres Therapeutics, Inc., a clinical-stage company, focuses on developing biotherapeutics for serious diseases. The company develops SER-155, an investigational oral live biotherapeutic to decolonize GI pathogens, enhance GI epithelial barrier integrity, and regulate immune response to prevent bacterial bloodstream infections, as well as other pathogen-associated negative clinical outcomes in patients undergoing allogeneic hematopoietic stem cell transplantation. It also develops SER-603, a LBP …

Sector: Healthcare Industry: Biotechnology Market Cap: $24.3M CIK: 1609809

Total Filings

Bullish Classifications

Bearish Classifications

Insider Transactions

Material Events (8-K)

Periodic Reports

Rule-based classifications for MCRB currently lean bearish. Of the 20 filing records displayed, 4 carry bearish classifications (such as insider sales or negative 8-K disclosures) versus 0 bullish. This does not necessarily signal fundamental deterioration — insiders sell for many reasons — but it is worth monitoring alongside the company's core financial metrics.

MCRB Filing Activity Snapshot 2026-07-08 — 2026-08-18

Insider Transactions (Form 4)

0 buys vs 4 sells

Net insider selling in this period — insiders sell for many reasons beyond conviction.

Largest Form 144 Filing

$1.2K

Shaff Eric D. (Director) · 2026-08-18

263 shares · Form 4

Insider Transactions 16 · Forms 3, 4 and 5

A Form 4 is filed within two business days of a company insider — an officer, a director, or a holder of more than ten percent of the stock — changing their position in the shares. All 16 filings in this group are Form 4s for Seres Therapeutics, Inc.

The difficulty with reading these filings as a group is that a single form type covers transactions that mean entirely different things. An executive spending their own money to buy stock and an executive having shares withheld to pay tax on a vesting grant both appear as a Form 4. Every filing below is therefore tagged with the nature of the underlying transaction, taken from the transaction code reported on the form itself.

Across the 16 insider filings shown, the breakdown is 12 compensation award and 4 open-market sale. 4 of them involved a discretionary open-market trade; the rest are compensation and administrative mechanics.

What each transaction type means

Compensation award ×12: Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.
Open-market sale ×4: The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Form 4 Open-market sale Insider Selling 2026-08-18

MCRB insider Brady Kelly (See Remarks) sold 64 shares (~$291.20)

Brady Kelly, listed as See Remarks at Seres Therapeutics, Inc., reported an open-market sale of 64 MCRB shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`M`	Option exercise	181	—	—
`S`	Open-market sale	64	$4.55	$291.20
`M`	Option exercise derivative · Restricted Stock Units	90	—	—
`M`	Option exercise derivative · Restricted Stock Units	91	—	—

Filing: Form 4 (Insider Transaction) Insider: Brady Kelly (See Remarks) Shares: 64 Est. Value: $291.20

View on SEC EDGAR → Open Filing Document →

Form 4 Open-market sale Insider Selling 2026-08-18

MCRB insider Shaff Eric D. (Director) sold 263 shares (~$1.2K)

Shaff Eric D., listed as Director at Seres Therapeutics, Inc., reported an open-market sale of 263 MCRB shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`M`	Option exercise	722	—	—
`S`	Open-market sale	263	$4.55	$1.2K
`M`	Option exercise derivative · Restricted Stock Units	390	—	—
`M`	Option exercise derivative · Restricted Stock Units	332	—	—

Filing: Form 4 (Insider Transaction) Insider: Shaff Eric D. (Director) Shares: 263 Est. Value: $1.2K

View on SEC EDGAR → Open Filing Document →

Form 4 Open-market sale Insider Selling 2026-08-18

MCRB insider Henn Matthew R (See Remarks) sold 81 shares (~$368.55)

Henn Matthew R, listed as See Remarks at Seres Therapeutics, Inc., reported an open-market sale of 81 MCRB shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`M`	Option exercise	238	—	—
`S`	Open-market sale	81	$4.55	$368.55
`M`	Option exercise derivative · Restricted Stock Units	140	—	—
`M`	Option exercise derivative · Restricted Stock Units	98	—	—

Filing: Form 4 (Insider Transaction) Insider: Henn Matthew R (See Remarks) Shares: 81 Est. Value: $368.55

View on SEC EDGAR → Open Filing Document →

Form 4 Open-market sale Insider Selling 2026-08-18

MCRB insider DesRosier Thomas (See Remarks) sold 82 shares (~$373.10)

DesRosier Thomas, listed as See Remarks at Seres Therapeutics, Inc., reported an open-market sale of 82 MCRB shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`M`	Option exercise	245	—	—
`S`	Open-market sale	82	$4.55	$373.10
`M`	Option exercise derivative · Restricted Stock Units	133	—	—
`M`	Option exercise derivative · Restricted Stock Units	112	—	—

Filing: Form 4 (Insider Transaction) Insider: DesRosier Thomas (See Remarks) Shares: 82 Est. Value: $373.10

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-07-10

MCRB insider Form 4 filed for equity award, exercise, or tax withholding

Graves Kurt (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Stock Option (right to buy)	6,500	—	—

Filing: Form 4 (Insider Transaction) Insider: Graves Kurt (Director)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-07-10

MCRB insider Form 4 filed for equity award, exercise, or tax withholding

Kender Richard N (Director, See Remarks) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Stock Option (right to buy)	50,000	—	—

Filing: Form 4 (Insider Transaction) Insider: Kender Richard N (Director, See Remarks)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-07-10

MCRB insider Form 4 filed for equity award, exercise, or tax withholding

Henn Matthew R (See Remarks) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Stock Option (right to buy)	25,000	—	—

Filing: Form 4 (Insider Transaction) Insider: Henn Matthew R (See Remarks)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-07-10

MCRB insider Form 4 filed for equity award, exercise, or tax withholding

Thorell Marella (See Remarks) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Stock Option (right to buy)	7,500	—	—

Filing: Form 4 (Insider Transaction) Insider: Thorell Marella (See Remarks)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-07-10

MCRB insider Form 4 filed for equity award, exercise, or tax withholding

Fraser Claire (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Stock Option (right to buy)	6,500	—	—

Filing: Form 4 (Insider Transaction) Insider: Fraser Claire (Director)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-07-10

MCRB insider Form 4 filed for equity award, exercise, or tax withholding

Dere Willard H (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Stock Option (right to buy)	6,500	—	—

Filing: Form 4 (Insider Transaction) Insider: Dere Willard H (Director)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-07-10

MCRB insider Form 4 filed for equity award, exercise, or tax withholding

Ausiello Dennis A (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Stock Option (right to buy)	6,500	—	—

Filing: Form 4 (Insider Transaction) Insider: Ausiello Dennis A (Director)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-07-10

MCRB insider Form 4 filed for equity award, exercise, or tax withholding

Shaff Eric D. (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Stock Option (right to buy)	6,500	—	—

Filing: Form 4 (Insider Transaction) Insider: Shaff Eric D. (Director)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-07-10

MCRB insider Form 4 filed for equity award, exercise, or tax withholding

Rosiello Robert L. (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Stock Option (right to buy)	6,500	—	—

Filing: Form 4 (Insider Transaction) Insider: Rosiello Robert L. (Director)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-07-10

MCRB insider Form 4 filed for equity award, exercise, or tax withholding

Berenson Stephen (Director) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Stock Option (right to buy)	6,500	—	—

Filing: Form 4 (Insider Transaction) Insider: Berenson Stephen (Director)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-07-10

MCRB insider Form 4 filed for equity award, exercise, or tax withholding

DesRosier Thomas (See Remarks) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Stock Option (right to buy)	7,500	—	—

Filing: Form 4 (Insider Transaction) Insider: DesRosier Thomas (See Remarks)

View on SEC EDGAR → Open Filing Document →

Form 4 Compensation award Tax / Compensation Filing 2026-07-10

MCRB insider Form 4 filed for equity award, exercise, or tax withholding

Brady Kelly (See Remarks) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code	Nature	Shares	Price	Value
`A`	Compensation award derivative · Stock Option (right to buy)	18,750	—	—

Filing: Form 4 (Insider Transaction) Insider: Brady Kelly (See Remarks)

View on SEC EDGAR → Open Filing Document →

Material Events 3 · Form 8-K

An 8-K reports a material event in the window between scheduled reports. There are 3 in this period for Seres Therapeutics, Inc. Each 8-K names the item number it is filed under, and that number is the fastest way to tell a routine disclosure from a consequential one.

Item 2.02 is an earnings release, Item 5.02 is a change of directors or officers, and Item 1.01 or 2.01 covers a material agreement or a completed acquisition. Item 7.01 and Item 8.01 are the general-purpose disclosure items and carry no fixed meaning on their own.

Form 8-K Material Company Update 2026-08-05

MCRB filed 8-K — material company event

Seres Therapeutics, Inc. filed an 8-K with the SEC reporting a material event. Summary unavailable — view the original SEC filing for the full text.

Filing: 8-K (Material Event)

View on SEC EDGAR → Open Filing Document →

Form 8-K Material Company Update 2026-08-04

MCRB filed 8-K — material company event

Seres Therapeutics, Inc. filed an 8-K with the SEC reporting a material event. Summary unavailable — view the original SEC filing for the full text.

Filing: 8-K (Material Event)

View on SEC EDGAR → Open Filing Document →

Form 8-K Material Company Update 2026-07-08

MCRB filed 8-K — material company event

Seres Therapeutics, Inc. filed an 8-K with the SEC reporting a material event. Summary unavailable — view the original SEC filing for the full text.

Filing: 8-K (Material Event)

View on SEC EDGAR → Open Filing Document →

Periodic Reports 1 · Forms 10-K and 10-Q

The periodic reports are where the audited and reviewed financial statements live. This period contains 1 quarterly report (10-Q) for Seres Therapeutics, Inc.

The two are not equivalent in weight. A 10-K is audited by an external firm and includes the full risk factor disclosure, business description and management discussion; a 10-Q is unaudited, reviewed rather than examined, and much shorter. When a figure in a quarterly report is later revised, the annual report is usually where the correction appears.

An amended report — 10-K/A or 10-Q/A — restates or corrects something in the original filing, and is worth reading against the version it replaces.

Form 10-Q Quarterly Report 2026-08-05

MCRB filed Quarterly Report (10-Q)

Seres Therapeutics, Inc. filed its quarterly report with the SEC. This report includes unaudited financial statements and management discussion for the quarter.

Filing: 10-Q (Quarterly Report)

View on SEC EDGAR → Open Filing Document →

How we classify Seres Therapeutics, Inc.'s filings

Straight from EDGAR

Each displayed record links to an original source document. StrongBuyAnalytics provides navigation and brief excerpts or summaries, not the filing itself. Parsing may omit context or contain errors, so read the original document in full.

Transaction codes, not guesswork

The nature shown on each insider filing comes from the transaction code the filer entered on the form itself — P for an open-market purchase, A for a compensation award, F for shares withheld to pay tax, M for an option exercise. Where one filing contains several codes, the transaction table lists them line by line.

Why the distinction matters

Insider activity is routinely summarised as buying or selling, which flattens together decisions that mean very different things. Shares withheld for tax on a vesting grant are an automatic administrative step; shares bought on the open market are someone committing their own money at the current price.

What this page does not tell you

A filing records what happened, not why. Form 4 does not always disclose whether a sale was executed under a pre-arranged Rule 10b5-1 plan, and no single filing is a basis for a decision on MCRB. Read these alongside the fundamentals rather than in isolation.

Frequently Asked Questions — MCRB SEC Filings

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MCRB Full Analysis

Publisher, sources & limitations — September 15, 2026. StrongBuyAnalytics provides navigation and brief excerpts or summaries for educational use. Original filings remain at SEC EDGAR or other displayed source links; StrongBuyAnalytics does not author them. Filing dates are source dates, not publication dates for this page. Coverage can be delayed, incomplete, amended, or unavailable because of SEC/source availability, parsing, caching, or outages. Verify every material statement in the original filing.

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