The MBX Biosciences, Inc. (Nasdaq: MBX) SEC filings page on Stock Titan provides access to the company’s regulatory disclosures as filed with the U.S. Securities and Exchange Commission. As a clinical-stage biopharmaceutical company and emerging growth company, MBX uses filings such as Forms S-1, 10-K, 10-Q, and 8-K to describe its Precision Endocrine Peptide™ (PEP™) platform, clinical programs, risk factors, and capital-raising activities.
In its S-1 registration statement, MBX outlines its focus on novel precision peptide therapies for endocrine and metabolic disorders and details key product candidates, including canvuparatide (MBX 2109) for chronic hypoparathyroidism, imapextide (MBX 1416) for post-bariatric hypoglycemia, and MBX 4291 for obesity. Subsequent 8-K filings report material events such as topline results from the Phase 2 Avail™ trial of canvuparatide, initiation of the Phase 1 trial of MBX 4291, public equity offerings, and changes in board and committee roles.
Through this page, users can review MBX’s periodic financial reports, which discuss research and development spending, cash and marketable securities, and expectations about funding operations, as well as prospectus materials that describe intended uses of offering proceeds. Form 8-K filings also summarize key clinical data, trial designs, and future development plans for the company’s programs.
Stock Titan enhances these filings with AI-powered summaries that highlight the main points of lengthy documents, helping readers quickly understand topics such as clinical results, financing terms, and governance updates. Real-time updates from EDGAR, along with structured access to material event reports and registration statements, make this page a central resource for analyzing MBX’s regulatory and financial disclosures.
MBX Biosciences (MBX) reported an insider transaction by its President & CEO and Director on 10/24/2025. The executive exercised a stock option (Code M) to acquire 182,859 shares of common stock at an exercise price of $3.25 per share. Following the transaction, beneficial ownership stood at 664,256 shares held directly and 468,277 shares held indirectly through a revocable trust. The filing lists 129,708 derivative securities (options) remaining post-transaction. The option began vesting monthly from 11/07/2022 and is scheduled to fully vest by 11/07/2026, with early-exercise permitted subject to an issuer repurchase right.
MBX Biosciences (MBX) reported an insider share purchase by its President & CEO and Director on 10/20/2025. The reporting person bought 20,000 shares of common stock at a weighted average price of $13.6395, with trades executed between $13.60 and $13.6399.
Following the transaction, the filing lists 481,397 shares as directly owned and 468,277 shares as indirectly owned by a trust. The trust is identified as the P. Kent Hawryluk Revocable Trust, with the reporting person serving as trustee.
MBX Biosciences (MBX) reported an insider purchase by a director. On 10/17/2025, a revocable trust of the reporting person acquired 20,000 shares of common stock at $13.2492 per share (Transaction Code P). Following the transaction, 20,000 shares were beneficially owned indirectly by the trust. The filer notes a disclaimer of beneficial ownership beyond any pecuniary interest, as stated in the footnote.
Wellington Management reports ownership of 10.79% of MBX Biosciences, Inc. common stock as of 09/30/2025. The holding is recorded across four related Wellington entities with an aggregate beneficial ownership of 4,823,336 shares, of which shared voting power is reported at 4,558,297 and shared dispositive power at 4,823,336. The filing states these securities are owned of record by clients of Wellington investment advisers and were acquired and are held in the ordinary course of business, not for the purpose of changing or influencing control. The Schedule 13G/A identifies the organizational relationships among the reporting entities and lists Wellington Management Company LLP and several regional Wellington advisers as relevant investment-adviser entities.
OrbiMed affiliates report a change in beneficial ownership of MBX Biosciences common stock following an increase in the company's outstanding shares. The filing discloses that OrbiMed Advisors, OrbiMed Capital GP VII and OrbiMed Genesis collectively hold 4,002,887 shares, representing approximately 9.0% of 44,700,281 outstanding shares as stated in the issuer's prospectus. The reduction in reported percentage ownership is due to an increase in shares outstanding rather than a sale by the reporting persons. The filing also summarizes the relationships among the funds, their voting and dispositive authority and limited registration and piggyback rights under an Investors' Rights Agreement.
Amendment No. 1 to the Schedule 13D reports that Norwest Venture Partners XVI, LP and affiliated reporting persons experienced dilution in their ownership of MBX Biosciences, Inc. common stock as a result of an underwritten public offering that closed on September 26, 2025. The filing states each of the primary reporting persons beneficially owns 2,136,335 shares, representing 4.8% of the class based on 33,607,443 shares outstanding as of August 31, 2025 plus 11,108,055 shares issued in the offering; Ms. Aynechi’s aggregate beneficial ownership is reported as 2,140,989 shares (including 4,654 option shares). The reporting group ceased to be beneficial owners of more than 5% on September 26, 2025. The amendment discloses no transactions in the past 60 days and incorporates a prior joint filing agreement as an exhibit.
Frazier-affiliated investment vehicles disclosed their holdings in MBX Biosciences, Inc. Frazier Life Sciences X, L.P. directly holds 5,219,440 shares of common stock, representing 11.7% of the class based on the filing's share-count assumptions. Frazier Life Sciences Public Fund, L.P. holds 1,103,920 shares (2.5%), and Frazier Life Sciences Public Overage Fund, L.P. holds 325,653 shares (0.7%). The filing details pre-IPO purchases of preferred stock that converted at a 12.0221-to-1 ratio at IPO, IPO purchases at $16.00 per share, and a post-IPO purchase on September 26, 2025 by FLS X of 666,666 shares at $18.00 per share. The filing clarifies voting and dispositive power allocations among related entities and identifies exhibits, including an investors' rights agreement and a transactions exhibit.
MBX Biosciences Form 4 summary: On 09/26/2025 an affiliated investor group acquired 666,666 shares of MBX common stock at $18.00 per share. After the reported purchase the group beneficially owned 5,219,440 shares. The shares are held of record by Frazier Life Sciences X, L.P., with FHMLS X, L.P., FHMLS X, L.L.C., James N. Topper and Patrick J. Heron having shared voting and investment power; Heron is identified as a reporting person and a director and 10% owner. The filing is signed by an attorney-in-fact on behalf of the reporting parties.
MBX Biosciences entered into an underwriting agreement for an underwritten public stock offering. The company sold 11,108,055 shares of common stock at an offering price of $18.00 per share and granted underwriters a 30-day option to purchase up to an additional 1,666,208 shares at the same price, less discounts and commissions. The offering closed on September 26, 2025.
The transaction generated approximately $187.5 million in net proceeds. MBX plans to use this cash, together with its existing cash, cash equivalents and short-term investments, primarily to advance development of its three clinical-stage programs. Remaining funds are earmarked for discovery research and development, additional clinical development, and general corporate purposes including working capital and capital expenditures.
MBX Biosciences describes a pipeline built on a proprietary PEP platform targeting endocrine and metabolic diseases. Lead candidate canvuparatide (MBX 2109) is a PTH peptide prodrug designed for once-weekly dosing; Phase 1 showed a low peak-to-trough ratio, extended half-life, and no drug-related severe or serious adverse effects. A Phase 2 trial enrolled 64 hypoparathyroidism patients, enrollment completed March 2025, and topline data were reported September 2025. At 12 weeks, the primary composite endpoint was achieved in 63% (30/48) of treated patients vs 31% (5/16) placebo (p=0.042); 6-month OLE responder rate was 79% (44/56). Pharmacokinetics supported once-weekly dosing; bone turnover markers increased and urine calcium fell in responders. Safety: mostly mild/moderate adverse events, injection site reactions 19% vs 13% placebo, no deaths or drug-related serious adverse events.
Other programs include imapextide (MBX 1416) (long-acting GLP-1 receptor antagonist) with Phase 1 median half-life ~90 hours, favorable safety, End-of-Phase 1 FDA meeting completed and Phase 2a anticipated Q3 2025; and obesity candidate MBX 4291 (GLP-1/GIP co-agonist prodrug) with IND submitted June 16, 2025, FDA clearance July 2025, Phase 1 initiated September 2025 and topline results expected in 2027. The offering price referenced is $18.00 per share and the company expects proceeds to fund development, including approximately $248.0 million to advance the three clinical-stage programs.