MBX SEC Filing News — MBX Biosciences, Inc.

Latest SEC filings for MBX Biosciences, Inc. (MBX) 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: 2026-08-27.

MBX Biosciences, Inc., a clinical-stage biopharmaceutical company, focuses on the discovery and development of precision peptide therapies for the treatment of endocrine and metabolic disorders. Its lead product candidate is Canvuparatide (MBX 2109), a parathyroid hormone peptide prodrug, which is in Phase 3 clinical trial for the treatment of chronic hypoparathyroidism. The company is also developing Imapextide (MBX 1416), a long-acting glucagon-like peptide-1 (GLP-1) receptor antagonist that i…
Sector: Healthcare Industry: Biotechnology Market Cap: $2.5B
12
Total Filings
0
Bullish Classifications
1
Bearish Classifications
3
Insider Transactions
4
Material Events (8-K)
1
Periodic Reports
Rule-based classifications for MBX currently lean bearish. Of the 12 filing records displayed, 1 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.
MBX Filing Activity Snapshot 2026-06-10 — 2026-08-27
Insider Transactions (Form 4)
0 buys vs 1 sell
Net insider selling in this period — insiders sell for many reasons beyond conviction.
Largest Form 144 Filing
$280.0K
Bartram Richard · 2026-06-10
9,167 shares · Form 144
Form 144 Notices
4
Proposed insider sales filed — Form 144 is a notice of intent, not a confirmed transaction. Actual sales are confirmed via Form 4.
Insider Transactions 3 · 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 3 filings in this group are Form 4s for MBX Biosciences, 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 3 insider filings shown, the breakdown is 2 compensation award and 1 open-market sale. 1 of them involved a discretionary open-market trade; the rest are compensation and administrative mechanics.

What each transaction type means

Compensation award ×2
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 ×1
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 2026-08-05

MBX insider Azoulay Salomon (Chief Medical Officer) sold 370 shares (~$24.3K)

Azoulay Salomon, listed as Chief Medical Officer at MBX Biosciences, Inc., reported an open-market sale of 370 MBX 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
S Open-market sale 370 $65.77 $24.3K
Filing: Form 4 (Insider Transaction) Insider: Azoulay Salomon (Chief Medical Officer) Shares: 370 Est. Value: $24.3K
View on SEC EDGAR → Open Filing Document →
Form 4 Compensation award Tax / Compensation Filing 2026-08-04

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

Smither John W (Chief Financial Officer) 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 28,000 — —
A Compensation award derivative · Stock option (right to buy) 130,000 — —
Filing: Form 4 (Insider Transaction) Insider: Smither John W (Chief Financial Officer) Shares: 28,000
View on SEC EDGAR → Open Filing Document →
Form 4 Compensation award Tax / Compensation Filing 2026-08-04

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

Hoerter Steven L. (Director, President and CEO) 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 71,000 — —
A Compensation award derivative · Stock option (right to buy) 331,000 — —
Filing: Form 4 (Insider Transaction) Insider: Hoerter Steven L. (Director, President and CEO) Shares: 71,000
View on SEC EDGAR → Open Filing Document →
Proposed Insider Sales 4 · Form 144

A Form 144 is a notice of intent to sell restricted or control securities. It is not a record that anything was sold. MBX Biosciences, Inc. has 4 such notices in this period.

The distinction matters because a Form 144 is frequently reported as though it were a completed insider sale. The filer may sell all of the shares covered, some of them, or none at all, and there is no obligation to update the notice either way. A sale that is actually executed by an officer or director shows up separately on a Form 4, which is the filing to check before treating a proposed sale as a real one.

Form 144 Proposed Insider Sale 2026-08-17

MBX Form 144 filed for proposed insider sale by Hawryluk P. Kent (3,745 shares) ~$255.7K

Hawryluk P. Kent filed a Form 144 with the SEC indicating intent to sell MBX (MBX Biosciences, Inc.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Hawryluk P. Kent Shares: 3,745 Est. Value: $255.7K
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-08-04

MBX Form 144 filed for proposed insider sale by Hawryluk P. Kent (936 shares) ~$61.6K

Hawryluk P. Kent filed a Form 144 with the SEC indicating intent to sell MBX (MBX Biosciences, Inc.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Hawryluk P. Kent Shares: 936 Est. Value: $61.6K
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-08-04

MBX Form 144 filed for proposed insider sale by Azoulay Salomon (370 shares) ~$24.3K

Azoulay Salomon filed a Form 144 with the SEC indicating intent to sell MBX (MBX Biosciences, Inc.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Azoulay Salomon Shares: 370 Est. Value: $24.3K
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-06-10

MBX Form 144 filed for proposed insider sale by Bartram Richard (9,167 shares) ~$280.0K

Bartram Richard filed a Form 144 with the SEC indicating intent to sell MBX (MBX Biosciences, Inc.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Bartram Richard Shares: 9,167 Est. Value: $280.0K
View on SEC EDGAR → Open Filing Document →
Material Events 4 · Form 8-K

An 8-K reports a material event in the window between scheduled reports. There are 4 in this period for MBX Biosciences, 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 2026-08-27

MBX filed 8-K — material company event

MBX Biosciences, 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 2026-08-06

MBX filed 8-K — material company event

MBX Biosciences, 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 2026-07-13

MBX filed 8-K — material company event

MBX Biosciences, 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 2026-06-12

MBX filed 8-K — material company event

MBX Biosciences, 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 MBX Biosciences, 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 2026-08-06

MBX filed Quarterly Report (10-Q)

MBX Biosciences, 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 MBX Biosciences, 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 MBX. Read these alongside the fundamentals rather than in isolation.

Frequently Asked Questions — MBX SEC Filings

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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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