Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations.

You should read the following discussion and analysis of our financial condition and results of operations together with our audited financial statements and the related notes and other financial information included elsewhere in this Annual Report on Form 10-K (this "Annual Report"). This discussion and other parts of this Annual Report contain forward-looking statements that involve risks and uncertainties, such as statements regarding our plans, objectives, expectations, intentions and projections. Our actual results could differ materially from those discussed in these forward-looking statements. Factors that could cause or contribute to such differences include, but are not limited to, those discussed in the “Risk Factors” section of this Annual Report. You should carefully read the "Risk Factors" section of this Annual Report to gain an understanding of the important factors that could cause actual results to differ materially from our forward-looking statements. Please also see "Special Note Regarding Forward-Looking Statements". Our historical results are not necessarily indicative of the results that may be expected for any period in the future.

Overview

We are a clinical-stage biopharmaceutical company focused on the discovery, development and commercialization of novel precision peptide therapies for the treatment of endocrine and metabolic disorders. Our company was founded by global leaders with a transformative approach to peptide drug design and development. Leveraging this expertise, we designed our

proprietary Precision Endocrine PeptideTM (the "PEPTM") platform to overcome the key limitations of unmodified and modified peptide therapies and to improve clinical outcomes and simplify disease management for patients. Our PEPs are selectively engineered to have optimized pharmaceutical properties, including extended time-action profiles and consistent drug concentrations with low peak-to-trough concentration ratios, consistent exposure to target tissues, and less frequent dosing. We are advancing a pipeline of novel candidates for endocrine and metabolic disorders with clinically validated targets, established endpoints for regulatory approval, significant unmet medical needs and large potential market opportunities.

Our lead product candidate, canvuparatide (MBX 2109), is a parathyroid hormone ("PTH") peptide prodrug that is designed as a potential long-acting hormone replacement therapy for the treatment of chronic hypoparathyroidism ("HP"). Leveraging our proprietary PEPTM platform, we designed canvuparatide to treat the underlying pathophysiology of HP by providing a continuous, infusion-like exposure to PTH, with convenient once-weekly administration. In a Phase 1 clinical trial, canvuparatide demonstrated a low ratio between the highest concentration of active drug observed after a dose and the concentration of active drug observed immediately prior to the next dose ("peak-to-trough ratio"). This result is consistent with a continuous, infusion-like profile, and an extended half-life, potentially enabling the first once-weekly PTH dosing regimen for patients with HP. Canvuparatide was generally well-tolerated with no drug-related severe or serious adverse effects. In a Phase 2 clinical trial of 64 patients with HP, canvuparatide achieved the primary endpoint with a statistically significant responder rate at Week 12 and further demonstrated positive six-month responder results from the open-label extension portion of the trial. All patients completed the 12-week trial, and canvuparatide was generally well-tolerated, with no treatment-related serious adverse events or discontinuations. We completed an End of Phase 2 meeting with the U.S. Food and Drug Administration ("FDA") and expect to receive Scientific Advice with the European Medicines Agency in the first half of 2026. We also intend to present results from our Phase 2 clinical trial and report one-year follow-up data from our ongoing open-label extension study at a medical meeting in the second quarter of 2026; and initiate a Phase 3 clinical trial of canvuparatide in the third quarter of 2026.

Our lead obesity product candidate, MBX 4291, is designed to be a long-acting and highly potent "PEPTM glucagon-like peptide 1 ("GLP-1") / glucose-dependent insulinotropic polypeptide ("GIP") co-agonist prodrug with the goal of potential once-monthly dosing frequency and improved efficacy and tolerability relative to existing standards of care. In our preclinical studies, the active component of MBX 4291 demonstrated a similar activity profile and body weight loss in mice as tirzepatide, an approved weekly GLP-1/GIP co-agonist, and an extended duration of action of the active component of MBX 4291, supporting the potential for once-monthly administration. The results observed from our preclinical studies may not necessarily be predictive of the results of later-stage clinical trials that we may conduct. We are conducting a randomized, double-blind, placebo controlled Phase 1 clinical trial designed to evaluate safety, tolerability, pharmacokinetics, and pharmacodynamics of SAD and MAD doses in adults with obesity. Following the SAD and four-week MAD portions of the trial, we plan to evaluate multiple ascending doses of MBX 4291, or matching placebo, administered over 12 weeks in up to two cohorts consisting of 30 participants. Results from the planned 12-week MAD portion are expected in the fourth quarter of 2026. Beyond MBX 4291, we have a robust discovery pipeline including multiple programs in the lead optimization stage of development, and we expect to nominate two additional candidates in the second and third quarters of 2026.

Our program, imapextide (MBX 1416), is designed to be a long-acting GLP-1 receptor antagonist as a potential therapy for post-bariatric hypoglycemia ("PBH"), a chronic complication of bariatric surgery. Imapextide is designed as a convenient once-weekly therapy to reduce insulin secretion and increase blood glucose to reduce the frequency and severity of hypoglycemic events. In January 2025, we announced positive topline results from our Phase 1 SAD and MAD clinical trial of imapextide in healthy adult volunteers. Results from the Phase 1 clinical trial demonstrated dose-proportional increases in imapextide exposure, a median half-life of 90 hours, which is supportive of a once-weekly dosing regimen, and, at steady state, the median Tmax was between 36 and 48 hours. Imapextide was generally well-tolerated with a favorable safety profile and no treatment-related serious adverse events. We are conducting the STEADITM Phase 2a, an open-label clinical trial evaluating primary efficacy of subcutaneous imapextide in adult patients with PBH. Topline results are expected in the second quarter of 2026.

Since our inception, we have devoted substantially all of our resources to drug discovery and development of our product candidates, canvuparatide, imapextide and MBX 4291, and other preclinical programs, building our intellectual property portfolio, organizing and staffing our company, business planning, raising capital and providing general and administrative support for these operations. We do not have any products approved for sale and have not generated any revenue from product sales. In September 2024, we completed our initial public offering (the "IPO"), pursuant to which we issued and sold 11,730,000 shares of common stock (inclusive of 1,530,000 shares of commons stock sold pursuant to the underwriters' exercise of their option to purchase additional shares). The aggregate net proceeds received by us from the IPO were $170.5 million, after deducting underwriting discounts and commissions and other offering costs of $17.2 million. In September 2025, we completed an underwritten public offering (the "September 2025 Offering") of 11,108,055 shares of our common stock, which generated approximately $187.4 million in aggregate net proceeds, after deducting underwriting discounts and commissions and other offering costs of $12.5 million. In February 2026, we closed on the sale and issuance of an aggregate of

100

2,250,986 shares of our common stock, which generated gross proceeds of approximately $87.1 million. The Shares were sold pursuant to the Company's Open Market Sale AgreementSM with Jefferies, LLC dated November 6, 2025 and a shelf registration statement on Form S-3 (File No. 333-291308) previously filed by us and declared effective by the SEC in December 2025. We have historically funded our operations primarily from the issuance and sale of our common stock, convertible preferred stock and convertible notes, which have generated approximately $688.8 million in cumulative, aggregate gross proceeds to date.

We have incurred significant operating losses since inception and we expect to continue to incur substantial losses for the foreseeable future. Our ability to generate revenue sufficient to achieve profitability will depend heavily on the successful development and eventual commercialization of one or more of our product candidates. Our net losses were $87.0 million and $61.9 million for the years ended December 31, 2025 and 2024, respectively. We had an accumulated deficit of $224.5 million and $137.5 million as of December 31, 2025 and December 31, 2024, respectively.

We anticipate that our expenses and operating losses will increase substantially for the foreseeable future as we:

•

advance the development of our lead product candidates, canvuparatide, imapextide and MBX 4291, and future product candidates;

•

advance our current research activities and further develop our platform;

•

continue preclinical development and discover and develop future product candidates we may identify;

•

seek regulatory approval for any product candidates for which we successfully complete clinical trials;

•

establish either internally or through contract manufacturing organizations manufacturing capacity capabilities to supply our clinical trials in our pipeline and eventually for commercialization;

•

transition from a company with a research focus to a company capable of supporting commercial activities, including establishing sales, marketing, and distribution infrastructure;

•

attract, hire and retain additional research and development, clinical, commercial, general and administrative personnel;

•

develop, maintain, expand, protect and enforce our intellectual property portfolio;

•

defend against any claims by third parties that we have infringed, misappropriated or otherwise violated any intellectual property of any such third party;

•

acquire or in-license product candidates, intellectual property and technologies;

•

confirm, maintain or obtain freedom to operate for any of our owned or licensed technologies and product candidates;

•

establish and maintain collaborations; or

•

add operational, financial and management information systems and personnel.

We will not generate revenue from product sales unless and until we successfully complete clinical development and obtain regulatory approval for one or more product candidates. If we obtain regulatory approval for any product candidate and do not enter into a commercialization partnership, we expect to incur significant expenses related to developing our commercialization capability to support product sales, manufacturing, marketing, and distribution. As a result, we will need substantial additional funding to support our continuing operations and pursue our growth strategy. Until such time as we can generate significant revenue from product sales, if ever, we expect to finance our operations through a combination of equity offerings, debt financings, collaborations, strategic alliances, and marketing, distribution or licensing arrangements with third parties. We may be unable to raise additional funds or enter into such other agreements or arrangements when needed on favorable terms, or at all. If we fail to raise capital or enter into such agreements as and when needed, we may have to significantly delay, reduce or eliminate the development and commercialization of our platform or delay our pursuit of potential in-licenses or acquisitions.

We had cash, cash equivalents and marketable securities of $373.7 million and $262.1 million as of December 31, 2025 and December 31, 2024, respectively. We believe that our existing cash, cash equivalents and marketable securities will be sufficient to fund our operating expenses and capital expenditure requirements into 2029. We have based this estimate on assumptions that may prove to be wrong, and we could exhaust our available capital resources sooner than we expect. See “Liquidity and capital resources” herein and “Risk Factors—Risks related to financial position and need for capital.”

101

License agreement

Below is a summary of the key terms for our license agreement.

Indiana University Research And Technology Corporation Exclusive License Agreement

In June 2020, we entered into an Exclusive License Agreement with Indiana University Research and Technology Corporation ("IURTC"), a non-profit corporation organized under the laws of the State of Indiana, represented by The Trustees of Indiana University ("IU"), pursuant to which we have been granted an exclusive, royalty-bearing license to certain IURTC patent rights ("the Licensed Intellectual Property") developed by Dr. DiMarchi and other collaborators to further scientific research, for new product development, and for other applications in public interest, such license, the IURTC License Agreement. In particular, we have been granted an exclusive, royalty-bearing license to make, have made, use, have used, offer to sell, have offered for sale, sell, have sold, import and have imported products that are covered by the Licensed Intellectual Property ("Licensed Products"), with the right to sublicense to third parties. IURTC and IU have retained the right to (i) practice and use the Licensed Intellectual Property for non-commercial educational, research, and patient care and treatment purposes, and (ii) permit other non-profit and academic entities to practice and use the Licensed Intellectual Property for the same non-commercial purposes. Under the IURTC License Agreement, we agreed to use commercially reasonable efforts to develop, promote and sell Licensed Products in accordance with the IURTC License Agreement and any applicable laws. The IURTC License Agreement leverages IURTC’s expertise in peptide therapies as well as our scientific, clinical, and regulatory capabilities to accelerate the development of peptide treatments for people with endocrine and metabolic disorders. Canvuparatide, imapextide, and MBX 4291 are Licensed Products under the IURTC License Agreement. Any future product candidates developed pursuant to our sponsored research agreement with IU or otherwise covered by the Licensed Intellectual Property may be subject to the IURTC License Agreement.

As initial consideration for the license, we paid IURTC an immaterial issue fee. As additional consideration for the license, we are required to pay IURTC: (i) royalties with a rate based on net sales per calendar year; (ii) an annual maintenance fee of up to $0.1 million beginning in the first year in which the first commercial sale occurs; (iii) a mid-single digits percentage of any sublicensing revenue; and (iv) milestone payments in the event of successful achievement of specified development milestones up to an aggregate of $0.4 million. IURTC is also entitled to receive reimbursement for all patent prosecution and maintenance related expenses. Our tiered royalties are in the low single-digits on annual net sales of the Licensed Products. In the event that we are required to pay a non-affiliate third party consideration for intellectual property owned or controlled by such non-affiliate third party that we or a sublicensee licensed for the development of Licensed Products, we can deduct such amounts from the royalty payments up to a certain amount of the running royalties owed that year. The royalty term will terminate on a country-by-country basis as to each Licensed Product, until the expiration or termination of the last valid claim within the patent rights covering such Licensed Product in that country.

On January 5, 2024, we and IURTC entered into a fourth amendment to the IURTC License Agreement (the "Fourth Amendment"). The Fourth Amendment specifies IURTC is entitled to the receipt of additional clinical and regulatory milestones, as defined in the Fourth Amendment, up to an aggregate of $9.0 million. Following the execution of the Fourth Amendment, future remaining clinical and regulatory milestone payments in the IURTC License Agreement and all amendments totaled up to $9.3 million. In 2025, we paid a $1.0 million milestone payment to IURTC related to the initiation of the Phase 1 clinical trial of MBX 4291. At December 31, 2025, future remaining clinical and regulatory milestone payments in the IURTC License Agreement and all amendments totaled up to $8.3 million.

The IURTC License Agreement will expire at the expiration of the last of the patent rights covered in the IURTC License Agreement, unless terminated earlier by mutual agreement or by one of the parties. We may terminate the IURTC License Agreement with or without cause upon ninety (90) days prior written notice to IURTC. IURTC may terminate the IURTC License Agreement if we commit a material breach of the IURTC License Agreement and fail to cure the breach within the respective cure period after receipt of the notice of material breach or upon our failure to undertake certain activities in furtherance of commercial development goals. Upon termination of the IURTC License Agreement, all rights granted by IURTC will terminate and automatically revert to IURTC.

Components of results of operations

Operating expenses

Our operating expenses consist of (i) research and development expenses and (ii) general and administrative expenses.

102

Research and development

The largest component of our total operating expenses since our inception has been research and development activities. Research and development expenses are expensed as incurred and consist primarily of:

•

external research and development expenses incurred under agreements with contract research organizations ("CROs"), consultants and other third parties to conduct our clinical trials;

•

costs related to manufacturing our product candidates for preclinical studies and clinical trials, including agreements with contract development and manufacturing organizations ("CDMOs");

•

license fees, including any milestone-based payments;

•

compensation and benefits, including stock-based compensation expense, for research and development personnel;

•

the costs of acquiring research and development supplies and services;

•

manufacturing process development costs;

•

costs associated with regulatory activities;

•

costs incurred in development of intellectual property;

•

other outside services and consulting costs; and

•

an allocated portion of facilities and other infrastructure costs associated with our research and development activities.

We expect our research and development expenses to increase substantially for the foreseeable future as we continue to invest in research and development activities to advance our programs and conduct clinical trials. The process of conducting the necessary clinical research to obtain regulatory approval is costly and time-consuming, and the successful development of our product candidates is highly uncertain. As a result, expenses may vary significantly based on factors such as:

•

the timing and progress of research and development, preclinical and clinical development activities;

•

the number, scope and duration of clinical trials required for regulatory approval of our existing or future product candidates;

•

the costs, timing, and outcome of regulatory review of any of our existing or future product candidates by the FDA and comparable foreign regulatory authorities, including the potential for such authorities to require that we perform more preclinical studies or clinical trials than those that we currently expect or for such authorities to change their requirements on studies that had previously been agreed to;

•

the costs of manufacturing clinical and commercial supplies of our existing or future product candidates;

•

our ability to maintain existing, and establish new, strategic collaborations, licensing or other arrangements, and the financial terms of any such agreements, including the timing and amount of any future milestone, royalty or other payments due under any such agreement;

•

our implementation of various computerized informational systems and efforts to enhance operational systems;

•

expenses incurred to attract, hire and retain skilled research and development personnel;

•

per subject clinical trial costs;

•

the number of sites included in our clinical trials;

•

the countries in which our clinical trials are conducted;

•

length of time required to enroll subjects and initiate our clinical trials;

•

the number of subjects that participate in our clinical trials;

•

the drop-out and discontinuation rate of subjects;

•

potential additional safety monitoring requested by regulatory agencies;

•

the duration of subject participation in our clinical trials and follow-up, including the duration of open label extensions;

103

•

the timing of license agreement milestone payments related to development, regulatory and commercial events;

•

manufacturing success with patient materials;

•

mitigation/responses to potential health authority questions and/or inspections;

•

the degree to which we obtain, maintain, defend and enforce our intellectual property rights; and

•

the extent to which we establish collaboration, licensing or similar arrangements and the performance of any related third parties.

A change in the outcome of any of these variables with respect to the development of any of our existing or future product candidates could significantly change the costs and timing associated with the development of that product candidate.

General and administrative

General and administrative expenses consist primarily of compensation and benefits, including stock-based compensation expense for general and administrative personnel; other expenses for outside professional services, including legal fees relating to intellectual property and corporate matters; professional fees for accounting, auditing, consulting and tax services; insurance costs; administrative travel expenses; website development costs; marketing and public relations costs; and facilities, information technology and other allocated overhead costs.

We anticipate that our general and administrative expenses will increase in the future as we increase our headcount to support continued growth of our research and development activities. We also anticipate that we will incur increased accounting, audit, legal, regulatory, compliance and director and officer insurance costs as well as investor and public relations expenses associated with being a public company. We also expect our intellectual property expenses to increase as we expand our intellectual property portfolio.

Other income

Interest and other income, net

Total other income, net, is comprised of interest income earned on our cash and cash equivalents and marketable securities and amortization expense and accretion income on our marketable securities.

Results of operations

Comparison of the years ended December 31, 2025 and 2024

The following table summarizes our results of operations for the years ended December 31, 2025 and 2024 (in thousands):

Years ended December 31, Change

Operating expenses:

Other income

Research and development expenses

The following table summarizes our research and development expenses for the periods indicated (in thousands):

104

Year ended December 31, Change

Direct research and development program expenses:

Indirect research and development costs:

Personnel related costs (including stock-based compensation) 16,524 10,245 6,279

(1) Prior period amounts for MBX 4291 have been reclassified to conform to current period presentation.

Research and development expenses were $79.2 million for the year ended December 31, 2025, as compared to $57.4 million for the year ended December 31, 2024. The increase of $21.7 million consisted of the following:

Direct research and development program expenses related to canvuparatide increased by $15.6 million primarily due to increased activities related to conduct of the Phase 2 clinical trial and increased manufacturing in preparation for the Phase 3 clinical trial. Direct program expenses related to MBX 4291 increased by $1.9 million primarily due to a $1.0 million IURTC milestone that was triggered in the year ended December 31, 2025 and the start of the phase 1 clinical trial, partially offset by a decrease in costs related to IND-enabling preclinical studies. Direct program expenses related to imapextide decreased by $7.4 million, primarily due to the completion of the Phase 1 clinical trial in the first quarter of 2025, partially offset by costs related to the start of the Phase 2a clinical trial. Direct program expenses for preclinical and other programs increased by $4.7 million primarily due to pipeline candidate development activities. Personnel-related costs (including stock-based compensation), increased by $6.3 million, primarily due to increased headcount and stock-based compensation expense. Facility-related and other, which include allocated overhead, including rent, repairs and maintenance costs, common facilities and information technology-related expenses allocated to research and development increased by $0.7 million.

General and administrative expenses

General and administrative expenses were $18.9 million for the year ended December 31, 2025, as compared to $10.8 million for the year ended December 31, 2024. The increase of $8.1 million was primarily due to higher professional fees related to legal, accounting and consulting services and higher personnel-related costs, including compensation, benefits and stock-based compensation, as we expanded our infrastructure to support growth in our operations.

Interest and other income, net

Interest and other income, net, which includes interest income and amortization of premiums and discounts on our investments in marketable securities, were $11.1 million for the year ended December 31, 2025, as compared to $6.3 million for the year ended December 31, 2024. The increase of $4.8 million was due to increased interest on our cash, cash equivalents and marketable securities, which increased primarily due to the September 2025 Offering.

Liquidity and capital resources

Sources of liquidity

Since our inception, we have incurred significant operating losses. We have historically funded our operations primarily through our IPO, the September 2025 Offering, sales pursuant to our Open Market Sale Agreement, and sales of our convertible preferred stock and convertible notes, which have generated approximately $688.8 million in cumulative, aggregate gross proceeds to date. As of December 31, 2025 and December 31, 2024, we had $373.7 million and $262.1 million in cash, cash equivalents and marketable securities, respectively. We have not yet generated any revenue from product sales and do not expect to in the foreseeable future as our product candidates are in various phases of clinical and preclinical development.

105

Future funding requirements

We expect our expenses to increase substantially in connection with our ongoing activities, particularly as we advance the development of our product candidates. In addition, we expect to incur additional costs associated with operating as a public company. The timing and amount of our operating expenditures will depend largely on:

•

the timing and progress of research and development, preclinical and clinical development activities;

•

the number, scope and duration of clinical trials required for regulatory approval of our existing or future product candidates;

•

the costs of manufacturing clinical and commercial supplies of our existing or future product candidates;

•

the costs and timing of future commercialization activities, including product manufacturing, marketing, sales and distribution, for any of our existing or future product candidates for which we receive regulatory approval;

•

the cost of filing and prosecuting our patent applications, and maintaining and enforcing our patents and other intellectual property rights;

•

any product liability or other lawsuits related to our existing or future product candidates;

•

our implementation of various computerized informational systems and efforts to enhance operational systems;

•

expenses incurred to attract, hire and retain skilled personnel;

•

the costs of operating as a public company;

•

our ability to establish a commercially viable pricing structure and obtain approval for coverage and adequate reimbursement from third-party and government payers;

•

the extent to which we acquire or invest in businesses, products, and technologies;

•

the effect of competing technological and market developments; and

•

the impact of other factors, including inflation, economic uncertainty and geopolitical tensions, which may exacerbate the magnitude of the factors discussed above.

We had $373.7 million and $262.1 million in cash, cash equivalents and marketable securities as of December 31, 2025 and December 31, 2024, respectively. We believe that our existing cash, cash equivalents and marketable securities will be sufficient to fund our current operating plan for at least the next 12 months from the date of issuance of the accompanying audited financial statements. Based on our current operating plan, we estimate that our existing cash, cash equivalents and marketable securities will be sufficient to fund our projected operating expenses and capital expenditure requirements into 2029. We have based this estimate on assumptions that may prove to be wrong, and we could exhaust our available capital resources sooner than we expect.

Until such time, if ever, as we can generate substantial product revenue, we expect to finance our cash needs through a combination of equity offerings, debt financings, collaborations, strategic alliances, and marketing, distribution or licensing arrangements with third parties. To the extent that we raise additional capital through the sale of equity or convertible debt securities, ownership interest for existing investors may be materially diluted, and the terms of such securities could include liquidation or other preferences that adversely affect existing investors’ rights as a stockholder. Debt financing and preferred equity financing, if available, may involve agreements that include restrictive covenants that limit our ability to take specified actions, such as incurring additional debt, making capital expenditures or declaring dividends. If we raise funds through collaborations, strategic alliances or marketing, distribution or licensing arrangements with third parties, we may have to relinquish valuable rights to our technologies, future revenue streams, research programs or product candidates or grant licenses on terms that may not be favorable to us. If we are unable to raise additional funds through equity or debt financings or other arrangements when needed, we may be required to delay, reduce or eliminate our product development or future

106

commercialization efforts, or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves.

Cash flows

The following table summarizes our sources and uses of cash for the periods presented (in thousands):

Years ended December 31,

Net cash used in operating activities $ (79,949 ) $ (54,681 )

Net cash used in investing activities (83,705 ) (160,595 )

Net increase in cash and cash equivalents $ 25,938 $ 18,828

Cash flows from operating activities

Net cash used in operating activities for the year ended December 31, 2025 was $80.0 million. This was primarily due to our net loss of $87.0 million, partially offset by net cash provided by changes in our operating assets and liabilities of $1.6 million and non-cash charges of $5.4 million. The changes in our net operating assets and liabilities primarily consisted of a $4.3 million increase in net accounts payable and accrued expenses primarily related to balances with CDMOs, partially offset by a $2.7 million increase in prepaid expenses and other current assets related to prepaid balances with CROs. Non-cash charges primarily consisted of $8.7 million of stock-based compensation expense, $0.2 million of depreciation expense and $0.1 million of amortization of our ROU asset, partially offset by $3.6 million of net amortization and accretion of marketable securities.

Net cash used in operating activities for the year ended December 31, 2024 was $54.7 million. This was primarily due to our net loss of $61.9 million, partially offset by net cash provided by changes in our operating assets and liabilities of $4.6 million and non-cash charges of $2.6 million. The changes in our net operating assets and liabilities primarily consisted of a $7.1 million increase in accounts payable and accrued expenses primarily related to balances with CDMOs, partially offset by a $2.3 million increase in our prepaid expenses and other current assets related to prepaid balances with CROs. Non-cash charges primarily consisted of $5.2 million of stock-based compensation expense, partially offset by $2.9 million of net amortization and accretion of marketable securities.

Cash flows from investing activities

Net cash used in investing activities for the year ended December 31, 2025 was $83.7 million, which consisted of purchases of marketable securities of $358.1 million and purchases of property and equipment of $1.9 million, partially offset by maturities and redemptions of marketable securities of $276.4 million.

Net cash used in investing activities for the year ended December 31, 2024 was $160.6 million, which consisted of purchases of marketable securities of $239.5 million and purchases of property and equipment of $0.9 million, partially offset by maturities of marketable securities of $79.8 million.

Cash flows from financing activities

Net cash provided by financing activities for the year ended December 31, 2025 was $189.6 million, which consisted of proceeds of $187.9 million from the September 2025 Offering, net of underwriting discounts and commissions and $2.4 million of proceeds from the exercise of common stock options, partially offset by payments totaling $0.8 million related to offering costs for the September 2025 Offering.

Net cash provided by financing activities for the year ended December 31, 2024 was $234.1 million, which primarily consisted of proceeds from our IPO, net of underwriting discounts and commissions, of $174.5 million in September 2024, gross proceeds from our issuance of Series C Convertible Preferred Stock of $63.5 million in August 2024 and proceeds from the exercise of stock options of $0.4 million, partially offset by payments related to IPO costs of $4.1 million and preferred stock offering costs of $0.3 million.

107

Contractual obligations and commitments

Leases

We have entered into separate lease agreements for corporate office space and laboratory space, with terms extending through December 2028 and November 2026, respectively. The lease for our corporate office space was amended in May 2025 as further discussed in Note 9 to our audited condensed financial statements included elsewhere in this Annual Report. A new lease for laboratory space was signed in October 2025, effective December 1, 2025 through November 30, 2026. As of December 31, 2025, our future remaining operating lease payments were $1.0 million, with $0.5 million payable within the next twelve months, with respect to leases already commenced as of such date. As of December 31, 2024, our future remaining operating lease payments were $0.2 million, with $0.2 million payable within the next twelve months, with respect to leases already commenced as of such date.

Refer to Note 9 in our audited financial statements included elsewhere in this Annual Report for more information on our lease obligations.

License agreement and other agreements

Under the IURTC License Agreement, we have payment obligations that are contingent upon future events, such as the achievement of specified development, regulatory and commercial milestones, and in some cases, we are required to make royalty payments in connection with the sales of products developed under those agreements. Although we could be required to make milestone payments under the IURTC License Agreement, we are unable to estimate the timing or likelihood of achieving the milestones or making future product sales. For additional details regarding the IURTC License Agreement, see the section herein this Annual Report titled “Business-License Agreement.”

We enter into contracts in the normal course of business with clinical trial sites and clinical supply manufacturers and with vendors for preclinical studies and clinical trials, research supplies and other services and drugs for operating purposes. These contracts generally provide for termination after a notice period, and, therefore, are cancelable contracts. In addition, certain of our supply agreements contain minimum purchase commitments in certain situations, the timing and likelihood of which we cannot estimate at this time.

Recently issued accounting pronouncements

A description of recently issued accounting pronouncements that may potentially impact our financial position, results of operations or cash flows is disclosed in Note 2 to our audited financial statements included elsewhere in this Annual Report.

Critical accounting policies and significant judgments and estimates

Our management’s discussion and analysis of our financial condition and results of operations is based on our financial statements, which have been prepared in accordance with generally accepted accounting principles, ("GAAP"). The preparation of these financial statements requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements, as well as the reported expenses incurred during the reporting periods.

On an ongoing basis, we evaluate our estimates and judgments, including but not limited to those related to accrued research and development costs, the fair value of common stock and stock-based compensation expense and other fair value measurements. These estimates and assumptions are monitored and analyzed by us for changes in facts and circumstances, and material changes in these estimates and assumptions could occur in the future. Our estimates are based on our historical experience and on various other factors that we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Changes in estimates are reflected in reported results for the period in which they become known. Actual results may differ from these estimates under different assumptions or conditions.

Accrued research and development expenses

Research and development expenses are recognized as services are performed and as costs occur. As part of our process of preparing our financial statements, we are required to estimate our research and development expenses as of each balance sheet date. Research and development expense accruals are estimated based on the level of services performed, progress of the work orders, including the phase or completion of events, and contracted costs. This process involves reviewing open contracts and purchase orders and communicating with our personnel to identify the level of services that have been performed. We then

108

make estimates of levels of service performed when we have not yet been invoiced or otherwise notified of actual costs incurred as of the balance sheet date. We make significant judgments and estimates in determining the accrual balance at each reporting period based on the facts and circumstances known to us at that time.

There may be instances in which vendors will require nonrefundable advance payments for goods or services to be received in the future. Such advance payments for use in research and development activities are capitalized and recorded in prepaid expenses and other current assets, and then expensed as the related goods are delivered or the services are performed.

Although we do not expect our estimates to be materially different from amounts actually incurred, if our estimates of the level of services and timing of services performed differ from actual status and timing of services performed, it could result in us reporting amounts that are too high or too low in any particular reporting period. To date, there have been no material differences between estimates of such expenses and the amounts actually incurred.

Stock-based compensation expense

Stock-based compensation expense represents the cost of the grant date fair value of equity awards recognized over the requisite service period of the awards (usually the vesting period) on a straight-line basis. We estimate the fair value of all stock option grants using the Black-Scholes option pricing model and recognize forfeitures as they occur. Estimating the fair value of equity awards as of the grant date using valuation models, such as the Black-Scholes option pricing model, is affected by assumptions regarding a number of variables, including the risk-free interest rate, the expected stock price volatility, the expected term of stock options, the expected dividend yield and, prior to the IPO of our common stock, the fair value of the underlying common stock on the date of grant. Changes in the assumptions can materially affect the fair value and ultimately how much stock-based compensation expense is recognized. These inputs are subjective and generally require significant analysis and judgment to develop. See Note 12 to our audited financial statements included elsewhere in this Annual Report for information concerning certain of the specific assumptions we used in applying the Black-Scholes option pricing model to determine the estimated fair value of our stock options granted for the years ended December 31, 2025 and 2024, respectively. A portion of our stock option program allowed for early exercise of granted options, before vesting requirements have been satisfied. Shares acquired through the early exercise of options which have not vested at the time of any employee's termination may be purchased by us at the lower of the original exercise price or the then current fair market value. As of December 31, 2025, the unrecognized stock-based compensation expense related to stock options was $25.2 million and is expected to be recognized as expense over a weighted-average period of approximately 2.7 years. The intrinsic value of all outstanding stock options as of December 31, 2025 was approximately $97.8 million, based on the closing NASDAQ stock price of $31.54 per share as of December 31, 2025.

Prior to our IPO in September 2024, there was no public market for our common stock. As a result, prior to our IPO, the estimated fair value of our common stock was determined by our board of directors as of the date of each option grant, with input from management, considering our most recently available third-party valuations of common stock and our board of directors' assessment of additional objective and subjective factors that it believed were relevant and which may have changed from the date of the most recent valuation through the date of grant. Following our IPO, the fair value of our common stock is determined based on the quoted market price of our common stock.

Off-balance sheet arrangements

During the periods presented we did not have, nor do we currently have, any off-balance sheet arrangements as defined in the rules and regulations of the SEC.

Emerging growth company and smaller reporting company status

We qualify as an “emerging growth company,” as defined in the Jumpstart Our Business Startups Act of 2012 (the "JOBS Act"). As an emerging growth company, we may take advantage of specified reduced disclosure and other requirements that are otherwise applicable generally to public companies. These provisions include: (i) being permitted to present only two years of audited financial statements, in addition to any required unaudited interim financial statements, with correspondingly reduced “Management’s discussion and analysis of financial condition and results of operations” disclosure in this Annual Report; (ii) reduced disclosure about our executive compensation arrangements; (iii) not being required to hold advisory votes on executive compensation or to obtain stockholder approval of any golden parachute arrangements not previously approved; (iv) an exemption from the auditor attestation requirement in the assessment of our internal control over financial reporting pursuant to the Sarbanes-Oxley Act of 2002; and (v) an exemption from compliance with the requirements of the Public Company Accounting Oversight Board regarding the communication of critical audit matters in the auditor’s report on the financial statements.

109

We may take advantage of these exemptions for up to five years or such earlier time that we are no longer an emerging growth company. We would cease to be an emerging growth company on the date that is the earliest of (i) the last day of the fiscal year in which we have total annual gross revenues of $1.235 billion or more; (ii) the last day of our fiscal year following the fifth anniversary of the date of the completion of our IPO; (iii) the date on which we have issued more than $1.0 billion in nonconvertible debt during the previous three years; or (iv) the date on which we are deemed to be a large accelerated filer under the rules of the SEC. We may choose to take advantage of some but not all of these exemptions. We have taken advantage of reduced reporting requirements in this Annual Report. Accordingly, the information contained herein may be different from the information you receive from other public companies in which you hold stock. Additionally, the JOBS Act provides that an emerging growth company can take advantage of an extended transition period for complying with new or revised accounting standards. This allows an emerging growth company to delay the adoption of certain accounting standards until those standards would otherwise apply to private companies. We have elected to avail ourselves of this exemption and, therefore, while we are an emerging growth company we will not be subject to new or revised accounting standards at the same time that they become applicable to other public companies that are not emerging growth companies. As a result of this election, our audited financial statements and unaudited condensed financial statements may not be comparable to those of other public companies that comply with new or revised accounting pronouncements as of public company effective dates. We may choose to early adopt any new or revised accounting standards whenever such early adoption is permitted for private companies.

We are also a “smaller reporting company,” meaning that the market value of our shares held by nonaffiliates is less than $700 million and our annual revenue was less than $100 million during the most recently completed fiscal year. We may continue to be a smaller reporting company if either (i) the market value of our shares held by nonaffiliates is less than $250 million or (ii) our annual revenue was less than $100 million during the most recently completed fiscal year and the market value of our shares held by nonaffiliates is less than $700 million. If we are a smaller reporting company at the time we cease to be an emerging growth company, we may continue to rely on exemptions from certain disclosure requirements that are available to smaller reporting companies. Specifically, as a smaller reporting company, we may choose to present only the two most recent fiscal years of audited financial statements in our Annual Report on Form 10-K and, similar to emerging growth companies, smaller reporting companies have reduced disclosure obligations regarding executive compensation.

Item 7A. Quantitative and Qualitative Disclosures About Market Risk.

We are a smaller reporting company, as defined by Rule 12b-2 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and are not required to provide the information required by this Item.

Item 8. Financial Statements and Supplementary Data.

The financial statements required to be filed pursuant to this Item 8 are appended to this Annual Report beginning on page F-1. An index of those financial statements is found in Item 15, Exhibits and Financial Statement Schedules, of this Annual Report.

Item 9. Changes in and Disagreements With Accountants on Accounting and Financial Disclosure.

None.

Item 9A. Controls and Procedures.

Management's Evaluation of Disclosure Controls and Procedures

Our management, with the participation of our Chief Executive Officer and Chief Financial Officer, evaluated the effectiveness of our disclosure controls and procedures as of December 31, 2025. The term "disclosure controls and procedures," as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act, mean controls and other procedures of a company that are designed to ensure that information required to be disclosed by us in the reports that we file or submit under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in the Securities and Exchange Commission rules and forms, and that such information is accumulated and communicated to our management, including our Chief Executive Officer and Chief Financial Officer, as appropriate, to allow timely decisions regarding required disclosures.

Management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving their objectives and management necessarily applies its judgment in evaluating the cost-benefit relationship of possible controls and procedures. Based on the evaluation of our disclosure controls and procedures as

110

of December 31, 2025, our Chief Executive Officer and Chief Financial Officer concluded that, as of such date, our disclosure controls and procedures were effective at the reasonable level.

Management’s Annual Report on Internal Control Over Financial Reporting

Our management is responsible for establishing and maintaining adequate internal control over financial reporting, as defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act, to provide reasonable assurance regarding the reliability of our financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles in the United States. Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements.

Our management assessed the effectiveness of our internal control over financial reporting as of December 31, 2025 based on the criteria established by the Committee of Sponsoring Organizations of the Treadway Commission (COSO) in Internal Control - Integrated Framework (2013). Based on this assessment, our management concluded that our internal control over financial reporting was effective as of December 31, 2025.

This Annual Report on Form 10-K does not include an attestation report of our independent registered accounting firm due to a transition period established by rules of the SEC for newly public and emerging growth companies.

Changes in Internal Control over Financial Reporting

There have been no changes in our internal control over financial reporting (as defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act during the quarter ended December 31, 2025 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

Item 9B. Other Information.

(a) None.

(b) Trading Plans

During the three months ended December 31, 2025, none of our directors or officers (as defined in Rule 16a-1(f) of the Exchange Act) adopted or terminated any Rule 10b5-1 trading arrangements (as defined in Item 408(a) of Regulation S-K), except as follows:

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections.

Not applicable.

111

PART III

Item 10. Directors, Executive Officers and Corporate Governance.

The information required under this item is incorporated herein by reference to our definitive proxy statement pursuant to Regulation 14A, which proxy statement will be filed with the Securities and Exchange Commission not later than 120 days after the close of our fiscal year ended December 31, 2025.

We have adopted a code of business conduct and ethics for directors, officers, and employees, known as the Code of Business Conduct and Ethics. The Code of Business Conduct and Ethics is available on our website at https://investors.mbxbio.com/corporate-governance/governance-overview. We will promptly disclose on our website (i) the nature of any amendment to the policy that applies to our principal executive officer, principal financial officer, or controller, or persons performing similar functions and (ii) the nature of any waiver, including an implicit waiver, from a provision of the policy that is granted to one of these specified individuals, the name of such person who is granted the waiver and the date of the waiver. Shareholders may request a free copy of the Code of Business Conduct and Ethics from our Compliance Officer, c/o MBX Biosciences, 11711 N. Meridian Street, Suite 300 Carmel, Indiana.

We maintain an insider trading policy governing the purchase, sale and other dispositions of our securities that applies to all of our directors, officers, employees and other covered persons. We believe that the insider trading policy is reasonably designed to promote compliance with insider trading laws, rules and regulations, and listing standards applicable to us. It is also our policy to comply with all insider trading laws and regulations. A copy of our insider trading policy is filed as Exhibit 19.1 to this Annual Report on Form 10-K.

Item 11. Executive Compensation.

Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters.

Item 13. Certain Relationships and Related Transactions, and Director Independence.

Item 14. Principal Accounting Fees and Services.

Our independent public accounting firm is Ernst & Young LLP, Indianapolis, Indiana (PCAOB ID: 0042).

112

PART IV

Item 15. Exhibits, Financial Statement Schedules.

(1) Financial Statements.

For a list of the financial statements included herein, see Index to the Consolidated Financial Statements on page F-1 of this Annual Report, incorporated into this Item by reference.

(2) Financial Statement Schedules.

All financial schedules have been omitted because the required information is either presented in the consolidated financial statements or the notes thereto or is not applicable or required.

(3) Exhibits.

ExhibitNumber Description

10.4#* 2026 Inducement Plan and form of award agreement thereunder.

113

24.1* Power of Attorney (included on signature page to this Annual Report).

101.SCH Inline XBRL Taxonomy Extension Schema With Embedded Linkbase Documents

104 Cover Page Interactive Data File (embedded within the Inline XBRL document)

* Filed herewith.

**This certification will not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liability of that section. Such certification will not be deemed to be incorporated by reference into any filing under the Securities Act of 1933, as amended, or the Exchange Act, except to the extent specifically incorporated by reference into such filing.

# Indicates a management contract or any compensatory plan, contract or arrangement

† Portions of this exhibit (indicated by asterisks) will be omitted in accordance with the rules of the SEC because the Registrant has determined that information is both not material and is the type that the registrant treats as private or confidential.

+ Certain exhibits and schedules to these agreements have been omitted pursuant to Item 601(a)(5) and (6) of Regulation S-K. The registrant will furnish copies of any of the exhibits and schedules to the SEC upon request.

Item 16. Form 10-K Summary

Not applicable.

114

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, as amended, the Registrant has duly caused this Report to be signed on its behalf by the undersigned, thereunto duly authorized.

MBX Biosciences, Inc.

Date: March 12, 2026 By: /s/ P. Kent Hawryluk

P. Kent Hawryluk

President and Chief Executive Officer(Principal Executive Officer)

115

POWER OF ATTORNEY AND SIGNATURES

KNOW ALL BY THESE PRESENT, that each individual whose signature appears below hereby constitutes and appoints each of P. Kent Hawryluk and Steven L. Hoerter, as such person’s true and lawful attorney-in-fact and agent with full power of substitution and resubstitution, for such person in such person’s name, place and stead, in any and all capacities, to sign any and all amendments (including post-effective amendments) to this Annual Report on Form 10-K, and to file the same, with all exhibits thereto, and all documents in connection therewith, with the Commission granting unto each said attorney-in-fact and agent full power and authority to do and perform each and every act and thing requisite and necessary to be done in and about the premises, as fully to all intents and purposes as such person might or could do in person, hereby ratifying and confirming all that any said attorney-in-fact and agent, or any substitute or substitutes of any of them, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, this Annual Report on Form 10-K has been signed by the following person in the capacities and on the date indicated.

NAME TITLE DATE

/s/ Tiba AynechiTiba Aynechi Director March 12, 2026

/s/ Steven L. HoerterSteven L. Hoerter Director March 12, 2026

/s/ Patrick HeronPatrick Heron Director March 12, 2026

/s/ Edward T. Mathers Edward T. Mathers Director March 12, 2026

/s/ Ora PescovitzOra Pescovitz Director March 12, 2026

/s/ Steven RyderSteven Ryder Director March 12, 2026

/s/ Laurie StelzerLaurie Stelzer Director March 12, 2026

116

INDEX TO CONSOLIDATED FINANCIAL STATEMENTS

Report of Independent Registered Public Accounting Firm (PCAOB ID: 0042) F-2

Statements of Cash Flows for the Years ended December 31, 2025 and 2024 F-7

Notes to Financial Statements F-8

F-1

Report of Independent Registered Public Accounting Firm

To the Stockholders and the Board of Directors of MBX Biosciences, Inc.

Opinion on the Financial Statements

We have audited the accompanying balance sheets of MBX Biosciences, Inc. (the Company) as of December 31, 2025 and 2024, the related statements of operations and comprehensive loss, stockholders' equity (deficit) and convertible preferred stock and cash flows for the years then ended, and the related notes (collectively referred to as the “financial statements”). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2025 and 2024, and the results of its operations and its cash flows for the years then ended, in conformity with U.S. generally accepted accounting principles.

Basis for Opinion

These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company’s financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company's internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

/s/ Ernst & Young LLP

We have served as the Company’s auditor since 2023.

Indianapolis, Indiana

March 12, 2026

F-2

MBX BIOSCIENCES, INC.

BALANCE SHEETS

(in thousands, except share and per share amounts)

Years ended December 31,

Assets

Current assets:

Prepaid expenses and other current assets 7,834 5,137

Liabilities and Stockholders’ Equity

Current liabilities:

Operating lease liability, current 172 171

Share repurchase liability 2 42

Operating lease liability, net of current 424 —

Commitments and contingencies (Note 9)

Stockholders’ equity (deficit)

Accumulated other comprehensive income 286 55

Total liabilities and stockholders’ equity $ 385,144 $ 268,535

The accompanying notes are an integral part of these financial statements.

F-3

MBX BIOSCIENCES, INC.

STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS

(in thousands, except share and per share amounts)

Years ended December 31,

Operating expenses

Unrealized gain on marketable securities 285 54

Reclassification of net gains included in net loss (54 ) (59 )

Total other comprehensive gain (loss) 231 (5 )

Net loss attributable to common stockholders $ (86,971 ) $ (61,922 )

Net loss per common share, basic and diluted $ (2.38 ) $ (5.82 )

The accompanying notes are an integral part of these financial statements.

F-4

MBX BIOSCIENCES, INC.

STATEMENTS OF STOCKHOLDERS’ EQUITY (DEFICIT) AND CONVERTIBLE PREFERRED STOCK

(in thousands, except share amounts)

Common Stock Additional AccumulatedOther Total

Stock-based compensation expense — — 8,677 — — 8,677

Other comprehensive income — — — — 231 231

Stock-based compensation expense — — — — — — — — 5,222 — — 5,222

Other comprehensive loss — — — — — — — — — — (5 ) (5 )

F-5

The accompanying notes are an integral part of these financial statements.

F-6

MBX BIOSCIENCES, INC.

STATEMENTS OF CASH FLOWS

(in thousands)

Years ended December 31,

Cash flows from operating activities:

Adjustments to reconcile net loss to net cash used in operating activities:

Stock-based compensation expense 8,677 5,222

Non cash operating lease expense 133 106

Accretion and amortization of marketable securities, net (3,611 ) (2,928 )

Changes in operating assets and liabilities:

Prepaid expenses and other current assets (2,697 ) (2,348 )

Other assets 8 —

Operating lease right-of-use asset (501 ) —

Operating lease liability 425 (153 )

Net cash used in operating activities (79,949 ) (54,681 )

Cash flows from investing activities:

Purchases of property and equipment (1,929 ) (874 )

Call redemptions of marketable securities 8,500 —

Net cash used in investing activities (83,705 ) (160,595 )

Cash flows from financing activities:

Proceeds from exercise of common stock options 2,415 403

Payments related to offering costs (771 ) (4,062 )

Proceeds from the issuance of Series C Convertible Preferred Stock — 63,500

Preferred stock issuance costs — (279 )

Net increase in cash and cash equivalents 25,938 18,828

Cash and cash equivalents, beginning of period 49,351 30,523

Cash and cash equivalents, end of period $ 75,289 $ 49,351

Supplemental disclosure of non-cash investing and financing activities:

Vesting of early exercised stock options and founder shares $ 40 $ 232

Property and equipment in accounts payable and accrued liabilities 26 29

The accompanying notes are an integral part of these financial statements.

F-7

MBX BIOSCIENCES, INC.

NOTES TO FINANCIAL STATEMENTS

NATURE OF BUSINESS AND Liquidity

MBX Biosciences, Inc. (“MBX” or the “Company”) is a clinical-stage biopharmaceutical company focused on the discovery and development of novel precision peptide therapies for the treatment of endocrine and metabolic disorders. The Company is advancing a pipeline of novel candidates for endocrine and metabolic disorders. The Company was organized in August 2018 in Indiana as a Limited Liability Company and converted to a C corporation in the state of Delaware in April 2019. The Company maintains its corporate offices in Carmel, Indiana.

Since inception, the Company has devoted substantially all of its resources to drug discovery and development of its product candidates canvuparatide (MBX 2109), imapextide (MBX 1416) and MBX 4291, and other preclinical programs, building an intellectual property portfolio, organizing and staffing the Company, business planning, raising capital and providing general and administrative support for these operations. The Company does not have any products approved for sale and has not generated any revenue from product sales. The Company has historically funded its operations primarily through the issuance and sale of our common stock, including through our initial public offering (the "IPO"), convertible preferred stock and convertible notes, which generated approximately $401.8 million in aggregate gross proceeds, and an underwritten public offering in September 2025 (the "September 2025 Offering"), which generated approximately $199.9 million in aggregate gross proceeds, resulting in $601.7 million in cumulative, aggregate gross proceeds as of December 31, 2025.

September 2025 Public Offering

On September 24, 2025, the Company completed its September 2025 Offering, pursuant to which it sold 11,108,055 shares of its common stock at a purchase price per share of $18.00, resulting in net proceeds of approximately $187.4 million, after deducting the underwriting discounts, commissions and other offering costs.

Initial Public Offering

On September 16, 2024, the Company completed its initial public offering ("IPO"), pursuant to which it sold 11,730,000 shares of its common stock at a public offering price of $16.00 per share, resulting in net proceeds of approximately $170.5 million, after deducting underwriting discounts, commissions and other offering costs. Immediately prior to the closing of the IPO, the Company's outstanding convertible preferred stock automatically converted into 20,336,599 shares of common stock. Following the closing of the IPO, zero shares of convertible preferred stock were authorized, issued or outstanding.

Reverse Stock Split

On September 6, 2024, the Company effected a one-for-12.0221 reverse stock split of its issued and outstanding shares of common stock and a proportional adjustment to the existing conversion prices for the Company's convertible preferred stock (see Note 10). Accordingly, all issued and outstanding share and per share amounts of common stock and stock option awards for all periods presented in the accompanying financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect this reverse stock split. The par value and the number of authorized shares of the common stock and convertible preferred stock were not adjusted in connection with the reverse stock split.

Liquidity

From inception and through December 31, 2025, the Company has devoted substantially all of its efforts to drug discovery and development. The Company has a limited operating history, has incurred operating losses since inception and expects to continue to incur significant operating losses for the foreseeable future. The Company incurred net losses of $87.0 million and $61.9 million for the years ended December 31, 2025 and December 31, 2024, respectively. As of December 31, 2025, the Company has an accumulated deficit of $224.5 million and cash, cash equivalents and marketable securities of $373.7 million. Based on the Company’s current operating plan, management believes that existing cash, cash equivalents and marketable securities will be sufficient to fund the Company’s obligations for at least 12 months from the date of issuance of these financial statements.

F-8

Basis of presentation

The accompanying audited financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (US GAAP).

We operate as a single operating segment engaged in the discovery and development of novel precision peptide therapies for the treatment of endocrine and metabolic disorders. See Note 16 for additional information.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Use of Estimates

The preparation of financial statements in conformity with US GAAP requires management to make judgments, assumptions, and estimates that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of financial statements, and the reported amounts of income and expense during the reporting period. The most significant estimates relate to the determination of the fair value of stock option grants and estimates related to the amount of prepaid and accrued research and development expenses as of the balance sheet date. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment, and makes adjustments when the facts and circumstances dictate. These estimates are based on information available as of the date of the financial statements; therefore, actual results could differ from those estimates.

Cash and Cash Equivalents

The Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. As of December 31, 2025 and 2024, cash and cash equivalents consisted primarily of checking and savings deposits, money market fund holdings, and commercial paper.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to significant concentration of credit risk consist primarily of cash and cash equivalents. The Company’s investment policy includes guidelines regarding the quality of the financial institutions and financial instruments and defines allowable marketable securities that it believes minimizes the exposure to concentration of credit risk. The Company may invest in money market funds (minimum of $10 billion in assets), U.S. Treasury securities, corporate debt, bank debt, U.S. government-related agency securities, other sovereign debt, municipal debt and commercial paper. These deposits may exceed federally insured limits. The Company has not experienced any losses historically in these accounts.

Property and Equipment

Property and equipment are stated at cost less accumulated depreciation. Depreciation expense is recognized using the straight-line method over the estimated useful life of each asset, generally three to seven years. Leasehold improvements are depreciated over the shorter of the lease term or the estimated useful life of the asset. Upon retirement or sale, the cost of assets disposed of, and the related accumulated depreciation, are removed from the accounts and any resulting gain or loss is included in loss from operations in the period realized. Repairs and maintenance charges that do not increase the useful life of the assets are charged to operating expenses as incurred.

Impairment of Long-Lived Assets

The Company evaluates its long-lived assets, which consist primarily of property and equipment, for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the future undiscounted net cash flows expected to be generated by the asset. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the asset exceeds the fair value of the asset. No impairment losses have been recognized during the years ended December 31, 2025 and 2024.

F-9

Fair Value of Financial Instruments

Fair value is defined as the price that the Company would receive to sell an investment in a timely transaction or pay to transfer a liability in a timely transaction with an independent buyer in the principal market, or in the absence of a principal market, the most advantageous market for the investment or liability. A framework is used for measuring fair value utilizing a three-tier hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 investments) and the lowest priority to unobservable inputs (Level 3 investments).

The three levels of the fair value hierarchy are as follows:

•

Level 1 inputs: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities;

•

Level 2 inputs: Quoted prices in markets that are not considered to be active or financial instrument valuations for which all significant inputs are observable, either directly or indirectly; and

•

Level 3 inputs: Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable.

Financial instruments are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. The assessment of the significance of a particular input to the fair value measurement requires judgment and considers factors specific to the investment.

The Company’s money market funds and marketable securities are carried at fair value determined according to the fair value hierarchy described above (Level 1 and Level 2, respectively).

Research and Development Expenses

Research and development expenses include employee-related expenses, including salaries, benefits, travel and stock-based compensation expense; external research and development expenses incurred under arrangements with third parties, such as contract research organization agreements, contract manufacturing organization agreements, clinical sites and consultants; costs associated with preclinical and clinical activities; costs associated with required regulatory filings, licenses and fees; costs incurred in development of intellectual property; and an allocated portion of facilities and other infrastructure costs associated with our research and development activities. Costs incurred in connection with research and development activities, both internal and external, are expensed as incurred.

Costs are considered incurred based on an evaluation of the progress to completion of specific tasks under each contract using information and data provided to the Company by its clinical sites and vendors. These costs consist of direct and indirect costs associated with specific projects, as well as fees paid to various entities that perform certain research on behalf of the Company. Depending upon the timing of payments to the service providers, the Company recognizes prepaid expenses or accrued expenses related to these costs. These accrued or prepaid expenses are based on management’s estimates of the work performed under service agreements, milestones achieved, and experience with similar contracts. The Company monitors each of these factors and adjusts estimates accordingly.

Patent Costs

Costs related to filing and pursuing patent applications are expensed as incurred, as recoverability of such expenditures is uncertain. These costs are included in general and administrative expenses.

Stock-Based Compensation

The Company measures all stock options and other stock-based awards granted to employees, nonemployees, and directors based on the fair value on the date of the grant and recognizes compensation expense of those awards over the requisite service period, which is generally the vesting period of the respective award. Generally, the Company issues stock option awards with only service-based vesting conditions and records the expense for these awards using the straight-line method. The Company’s policy is to account for forfeitures when they occur.

The Company classifies stock-based compensation expense in its statement of operations in the same manner in which the award recipient’s payroll costs are classified or in which the award recipients’ service payments are classified.

F-10

The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model. The Company lacks company-specific historical and implied volatility information. Therefore, it estimates its expected stock volatility based on the historical volatility of a publicly traded set of peer companies and expects to continue to do so until it has adequate historical data regarding the volatility of its own traded stock price. The expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The expected term of stock options granted to non-employees is equal to the contractual term of the option award. The risk-free interest rate is determined by reference to the US Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is zero because the Company has never paid cash dividends on common stock and does not expect to pay any cash dividends in the foreseeable future.

In determining the exercise prices for options granted prior to the IPO of common stock, the Company considered the estimated fair value of the common stock as of the measurement date. The estimated fair value of the common stock prior to the IPO was determined at each grant date based upon a variety of factors, including the illiquid nature of the common stock, arm’s-length sales of the Company’s capital stock (including convertible preferred stock), the effect of the rights and preferences of the preferred shareholders, and the prospects of a liquidity event. Among other factors were the Company’s financial position and historical financial performance, forecasted future operations of the Company, an evaluation or benchmark of the Company’s competition, and the business climate in the marketplace at that time. Significant changes to the key assumptions underlying the factors used could result in different fair values of common stock at each valuation date.

Income Taxes

The Company recognizes net deferred tax assets to the extent that the Company believes these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. Valuation allowances are provided, if based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. If management determines that the Company would be able to realize its deferred tax assets in the future in excess of their net recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes.

The Company records uncertain tax positions on the basis of a two-step process whereby (1) management determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, management recognizes the largest amount of tax benefit that is more than 50 percent likely to be realized upon ultimate settlement with the related tax authority. The Company's policy is to recognize interest and/or penalties related to income tax matters in income tax expense. Any accrued interest and penalties are included within the related tax liability.

Leases

The Company records a right-of-use ("ROU") asset and lease liability for substantially all leases for which it is a lessee, in accordance with ASC 842. Leases with an initial term of 12 months or less are not recorded on the balance sheet. The Company recognizes lease expense for leases on a straight-line basis over the lease term. At inception of a contract, the Company considers all relevant facts and circumstances to assess whether or not the contract represents a lease by determining whether or not the contract conveys the right to control the use of an identified asset, either explicit or implicit, for a period of time in exchange for consideration.

Basic and Diluted Net Loss Per Share

The Company calculates basic and diluted net loss per share using the two-class method. The two-class method requires income available to common stockholders for the period to be allocated between common stock and participating securities, when outstanding, based upon their respective rights to receive dividends as if all income for the period had been distributed. The Company’s Convertible Preferred Stock are participating securities until their conversion to common stock. These participating securities do not contractually require the holders of such shares to participate in the Company’s losses. As such, net losses for the years presented were not allocated to the Company’s participating securities. Accordingly, basic net loss per share is computed by dividing the net loss by the weighted average number of common shares outstanding during the period, without consideration of potential dilutive securities. Diluted net loss per share is computed by dividing the net loss by the sum of the weighted average number of common shares outstanding during the period plus the dilutive effects of potentially dilutive securities outstanding during the period. Potentially dilutive securities include vested and unexercised stock options, restricted stock issued upon early exercise of stock options, restricted stock related to unvested founder shares and convertible preferred shares. The dilutive effect of stock options are computed using the treasury stock method and the dilutive effect of convertible

F-11

preferred shares is calculated using the if-converted method. The Company has generated a net loss for all periods presented, therefore diluted net loss per share is the same as basic net loss per share since the inclusion of potentially dilutive securities would be anti-dilutive.

Deferred offering costs

The Company capitalizes as deferred offering costs all direct and incremental legal, professional, accounting and other third-party fees incurred in connection with the Company's public offerings. The deferred offering costs are offset against the related proceeds upon the consummation of the applicable offering. As of December 31, 2025, the Company had $0.3 million of deferred offering costs included in other assets, of which $0.1 million were included in accounts payable and accrued expenses, in the accompanying balance sheets.

Comprehensive Income (Loss)

Comprehensive income (loss) represents net income (loss) for the period plus the results of certain other changes in stockholders’ equity. The Company’s comprehensive loss included unrealized gains (losses) related to marketable securities for the years ended December 31, 2025, and 2024.

Recently issued accounting pronouncements

From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board ("FASB") or other standard-setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on the accompanying financial statements and disclosures.

In December 2023, the FASB issued ASU 2023-09, Income Taxes: Improvements to Income Tax Disclosures (Topic 740), which establishes incremental disaggregation of income tax disclosures pertaining to the effective tax rate reconciliation and income taxes paid. This new standard is effective for fiscal years beginning after December 15, 2024. Early adoption is permitted. The standard should be applied prospectively to financial statements issued for periods after the effective date of this ASU with the option to apply it retrospectively. The Company adopted this standard retrospectively for the years ended December 31, 2025 and 2024, and the impact of the adoption of the amendments in this update was not material to the Company's financial position and results of operation for the years then ended, since the amendments are disclosure related only. See Note 13 for the income tax disclosures as required by Topic 740, as amended by ASU 2023-09.

In November 2024, the FASB issued ASU 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses, which is intended to provide more detailed information about specified categories of expenses (purchases of inventory, employee compensation, depreciation and amortization) included in certain expense captions presented on the face of our consolidated income statements. This new standard is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted. The amendments may be applied either (1) prospectively to financial statements issued for periods after the effective date of this ASU or (2) retrospectively to all prior periods presented in the consolidated financial statements. We are currently assessing the impact ASU 2024-03 will have on our financial statements, including our footnote disclosures.

FAIR VALUE Measurements

The following table presents information about the Company’s financial instruments as of December 31, 2025 and December 31, 2024, that are measured at fair value on a recurring basis and indicates the fair value hierarchy of the inputs the Company utilized to determine such fair value (in thousands):

Total Level 1 Level 2 Level 3

Financial assets:

Money market funds (cash equivalents) $ 61,646 $ 61,646 $ — $ —

Marketable securities (cash equivalents) 12,466 12,466 — —

F-12

Total Level 1 Level 2 Level 3

Financial assets:

Money market funds (cash equivalents) $ 37,989 $ 37,989 $ — $ —

Marketable Securities

The fair value of the Company’s marketable securities as of December 31, 2025 and December 31, 2024 is based on Level 1 and Level 2 inputs. The Company’s investments consist mainly of U.S. government and agency securities. Fair value is determined by taking into consideration valuations obtained from third-party pricing services. The third-party pricing services utilize industry standard valuation models, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker/dealer quotes on the same or similar securities; issuer credit spreads; benchmark securities; and other observable inputs. There were no transfers between levels within the fair value hierarchy during the years ended December 31, 2025 and December 31, 2024. The Company has assessed U.S. government treasuries as Level 1 and all other marketable securities as Level 2 within the fair value hierarchy of ASC 820. The Company classifies its entire investment portfolio as available-for-sale as defined in ASC 320, Debt Securities, and views all investments as available for use in its current operations. We have therefore classified all securities as current, even if we do not necessarily intend to dispose of the securities in the following year. Securities are carried at fair value with the unrealized gains (losses) reported in other comprehensive income (loss).

As of December 31, 2025 and December 31, 2024, none of the Company’s investments were determined to be other than temporarily impaired.

The following table summarizes the Company’s investments (in thousands):

Government and agency securities Cash equivalents $ 9,989 $ 1 $ — $ 9,990

The fair values of available-for-sale debt securities as of December 31, 2025, by contractual maturity, are summarized as follows (in thousands):

Due in one year or less $ 219,952

F-13

PREPAID EXPENSES and Other Current assets

Prepaid and other current assets consisted of the following (in thousands):

December 31,

Prepaid research and development expenses $ 4,853 $ 3,652

Total prepaid and other current assets $ 7,834 $ 5,137

PROPERTY AND EQUIPMENT, NET

Property and equipment, net consisted of the following (in thousands):

December 31,

Furniture and fixtures $ 303 $ 214

Computer equipment and software 81 81

Construction in progress 1,616 —

Less accumulated depreciation (670 ) (422 )

Property and equipment, net $ 2,735 $ 1,080

Depreciation expense was $0.2 million and $0.2 million for the years ended December 31, 2025 and 2024, respectively.

ACCRUED Expenses

Accrued expenses consisted of the following (in thousands):

December 31,

Compensation and benefits $ 4,321 $ 2,324

Research and development expenses 7,404 3,063

Other Assets

Other assets consisted of the following (in thousands):

December 31,

Security deposits $ 42 $ 50

Deferred offering costs 341 —

Total other assets $ 383 $ 50

Commitments and contingencies

Leases

In April 2022, the Company entered into an operating lease agreement for a principal executive office in Carmel, Indiana (the “Carmel Lease”). The Carmel Lease commenced in October 2022 and had an initial term of 39 months, a termination date of December 31, 2025, and an option to extend for 36 additional months at the Company’s discretion. The option to extend was not considered reasonably certain as of the lease inception. On May 9, 2025, the Company entered into the first amendment of

F-14

the Carmel Lease (the "First Amendment"). Pursuant to the terms of the First Amendment, the leased premises were expanded, and the lease term was extended through December 31, 2028, with an option to extend for 36 additional months at the Company’s discretion. The option to extend is not considered reasonably certain as of date of the First Amendment.

In December 2023, the Company entered into an operating lease agreement for laboratory space in Indianapolis, Indiana (the “Laboratory Lease”). The Laboratory Lease commenced in December 2023 and had a term of 12 months, terminating in December 2024. The Company entered into a new lease for laboratory space in August 2024, commencing in December 2024, and terminating in December 2025. In October 2025, the Company entered into a new operating lease agreement for laboratory space in Indianapolis, Indiana, commencing in December 2025 and terminating in November 2026. All laboratory leases are short-term leases with no corresponding lease liability or right-of-use asset recorded, and lease payments are recognized as expense on a straight-line basis over the lease terms.

The Company has no other operating or finance leases as of December 31, 2025, or December 31, 2024.

Pursuant to ASC 842, the Company evaluated the new terms of the First Amendment of the Carmel Lease and determined the First Amendment should be treated as a lease modification of the existing Carmel Lease. In accordance with the accounting guidance, the Company remeasured the lease liability as of May 9, 2025, the First Amendment commencement date, to reflect the changes in the lease payments and the change in the lease term. This resulted in an increase of $0.6 million to the Company's lease liability and a corresponding increase to its right-of-use asset as shown on the balance sheet as of December 31, 2025.

The future minimum rent payments relating to the Carmel Lease under the terms and conditions existing as of December 31, 2025, are summarized as follows (in thousands):

(in thousands) Amount

Total lease payments 703

Less: imputed interest (107 )

Present value of lease liabilities $ 596

The Company incurred $0.3 million and $0.2 million of rent expense for the years ended December 31, 2025, and 2024, respectively.

The following table summarizes the operating lease term and discount rate for the Carmel Lease as of December 31, 2025, and December 31, 2024:

December 31,

Weighted-average remaining lease term (years) 3.0 1.0

Weighted-average discount rate 11.0 % 8.0 %

Cash paid for amounts included in the measurement of the Company’s operating lease liability was $0.2 million and $0.2 million for the years ended December 31, 2025, and December 31, 2024, respectively.

The following table sets forth the amount of right-of-use assets and lease liabilities included on the Company’s balance sheet as of December 31, 2025, and December 31, 2024 (in thousands):

December 31,

Right-of use assets $ 487 $ 119

Operating lease liability, current 172 171

Operating lease liability, net of current 424 —

F-15

License agreement

In January 2024, the Company entered into an amendment (the "Amendment") for the Exclusive License Agreement with Indiana University Research and Technology Corporation (“IURTC”) (the “License Agreement”), to license certain intellectual property arising under the Master Research Agreement with The Trustees of Indiana University (the "Research Agreement"). The Amendment specifies IURTC is entitled to the receipt of additional clinical and regulatory milestones, as defined in the Amendment, up to an aggregate of $9.0 million. Following the execution of the Amendment, future remaining clinical and regulatory milestone payments in the License Agreement and all amendments totaled up to $9.3 million. In the year ended December 31, 2025, the Company paid a $1.0 million milestone payment to IURTC related to the initiation of the Phase 1 clinical trial of MBX 4291. At December 31, 2025, future remaining clinical and regulatory milestone payments in the IURTC License Agreement and all amendments totaled up to $8.3 million. In consideration for the license, the Company paid immaterial licensing fees to IURTC during the and years ended December 31, 2025, and December 31, 2024.

Legal proceedings

The Company is not currently a party to any material legal proceedings. At each reporting date, the Company evaluates whether a potential loss amount or a potential range of loss is probable and reasonably estimable under the provisions of the authoritative guidance that addresses accounting for contingencies. The Company expenses as incurred the costs related to its legal proceedings.

10.

Convertible preferred stock

Prior to its IPO, the Company issued Series A Convertible Preferred Stock, Series B Convertible Preferred Stock and Series C Convertible Preferred Stock.

On August 30, 2024, the Company's board of directors (the "Board") and stockholders approved the fourth amended and restated certificate of incorporation, which was effective immediately prior to the closing of the IPO on September 16, 2024, and which, among other things, authorized 10,000,000 undesignated shares of preferred stock, $0.0001 par value per share.

Immediately prior to the closing of the Company's IPO on September 16, 2024, pursuant to the reverse stock split and a proportional adjustment to the existing conversion ratios of each series of the Company's preferred stock as discussed further below, all of the Company's outstanding shares of convertible preferred stock were converted into an aggregate of 20,336,599 shares of common stock, as follows: 4,458,324 shares of common stock were issued as a result of the conversion of Series A convertible preferred stock; 10,750,183 shares of common stock were issued as a result of the conversion of Series B convertible preferred stock; and 5,128,092 shares of common stock were issued as a result of the conversion of Series C convertible preferred stock. Prior to the conversion of the Company's convertible preferred stock, holders of the Series A, Series B and Series C Convertible Preferred Stock had certain rights and preferences, including voting and conversion rights and dividend and liquidation preferences. The Company had no shares of convertible preferred stock outstanding at December 31, 2025.

Issuances of convertible preferred stock

In July 2020, the Company entered into a Series A convertible preferred stock purchase agreement (“Series A SPA”) under which it issued 29,112,081 shares of Series A Convertible Preferred Stock, for cash, at a price of $0.687 per share, for gross proceeds of $20.0 million (the “Initial Series A Closing”). The Company incurred issuance costs of $0.3 million in relation to the issuance of Series A Convertible Preferred Stock, which have been recorded as a reduction to the value of the Series A Convertible Preferred Stock in mezzanine equity in the accompanying balance sheets. The Series A SPA contained provisions that potentially obligated the Company to sell an additional 14,556,039 shares of Series A Convertible Preferred Stock at $0.687 per share in an additional closing contingent upon either the achievement of a regulatory milestone defined in the Series A SPA or upon the agreement of the Company’s Board and lead investor to waive the requirement to achieve the milestone. In the event that an Initial Series A Closing purchaser failed to purchase all of their required shares in the subsequent Series A closing, each of the Series A Convertible Preferred Stock held by such purchaser automatically converted into one-half of a share of common stock.

Concurrently with the Initial Series A Closing, convertible notes issued by the Company in 2019 and 2020, including accrued interest and accrued deferred compensation, plus interest, were converted into 8,474,865 shares of Series A convertible preferred stock at a conversion price equal to 90% of the Series A financing, or $0.6183, representing a total of $5.4 million.

F-16

On November 12, 2021, the Company sold 16,011,641 additional shares of Series A convertible preferred stock at the same terms and conditions as those contained in the initial Agreement. The gross proceeds from the sale of Series A Convertible Preferred Stock upon achieving the milestone event was $11.0 million at $0.687 per share. The Company incurred immaterial issuance costs in relation to the issuance of Series A Convertible Preferred Stock, which have been recorded as a reduction to the value of the Series A Convertible Preferred Stock in mezzanine equity in the accompanying balance sheets.

On November 7, 2022 (the “Initial Series B Closing”), the Company entered into a Series B preferred stock purchase agreement to issue certain investors Series B Convertible Preferred Stock at a purchase price of $0.90 per share ($0.0001 par value). The Company amended the Certificate of Incorporation (“Charter”) on November 7, 2022, which authorized the issuance of 129,240,032 shares of Series B Convertible Preferred Stock, in addition to 53,598,587 shares of Series A Convertible Preferred Stock issued and outstanding. The Company also executed the Amended and Restated Right of First Refusal and Co-Sale Agreement and the Amended and Restated Investors’ Rights Agreement.

The Initial Series B Closing resulted in the issuance of 40,545,552 shares of Series B Convertible Preferred Stock, at a price of $0.90 per share, for gross cash proceeds of $36.5 million. The Company incurred issuance costs of $0.4 million in relation to the issuance of Series B Convertible Preferred Stock, which have been recorded as a reduction to the value of the Series B Convertible Preferred Stock in mezzanine equity in the accompanying balance sheets. Concurrently with the Initial Series B Closing, the 2022 Notes, including accrued interest, were converted into 12,573,381 shares of Series B Convertible Preferred Stock at a conversion price equal to 90% of the Series B financing. After the Initial Closing, the Company agreed to sell on the same terms and conditions as the first sale, an additional 76,121,099 shares of Series B Preferred Stock (the “Series B Milestone Issuance”) upon achieving certain development milestones.

On August 15, 2023, the Company issued 76,121,099 shares of Series B Convertible Preferred Stock, at a price of $0.90 per share, for gross cash proceeds of $68.5 million in the Series B Milestone Issuance. The Company incurred immaterial issuance costs in relation to this issuance of Series B Convertible Preferred Stock, which have been recorded as a reduction to the value of the Series B Convertible Preferred Stock in mezzanine equity in the accompanying balance sheets.

On August 2, 2024, the Company entered into a Series C convertible preferred stock purchase agreement under which it issued 61,650,480 shares of Series C Convertible Preferred Stock, for cash, at a price of $1.03 per share, for gross proceeds of $63.5 million. The Company incurred issuance costs of $0.3 million in relation to the issuance of Series C Convertible Preferred Stock, which were initially recorded as a reduction to the value of Series C Convertible Preferred Stock.

The holders of the Series A, Series B and Series C Convertible Preferred Stock were entitled to the following rights and preferences:

Voting rights

Series A, Series B and Series C Convertible Preferred Stock were entitled to cast the number of votes equal to the number of whole shares of common stock into which the shares of Series A, Series B and Series C Convertible Preferred Stock held by such holder were then convertible as of the record date for determining stockholders entitled to vote on such matter.

Election of directors

The holders of record of shares of Series A Convertible Preferred Stock, exclusively and as a separate class, were entitled to elect three directors of the Company. The holders of record of shares of Series B Convertible Preferred Stock, exclusively and as a separate class, were entitled to elect one director of the Company. The holders of record of shares of Series C Convertible Preferred Stock, exclusively and as a separate class, were not entitled to elect any directors of the Company.

Non-cumulative dividend

Holders of Series A, Series B and Series C Convertible Preferred Stock, in preference to the holders of common stock, were entitled to receive, when, as and if declared by the Board of the Company, but only out of funds that are legally available therefor, cash dividends at the rate of eight percent (8%) of the Series A, Series B and Series C original issue price per annum on each outstanding share of Series A, Series B and Series C Convertible Preferred Stock (the “Preferred Dividends”). All such Preferred Dividends would have been payable only when, as and if declared by the Board of the Company and would have been non-cumulative. No dividends have been declared to-date as of December 31, 2025.

F-17

Conversion right

Each share of Series A, Series B and Series C Convertible Preferred Stock was to be automatically converted into common stock upon either (a) the closing of the sale of shares of common stock to the public at a price of at least $2.061, $2.25 or $2.25, respectively, per share (subject to appropriate adjustment in the event of any stock dividend, stock split, combination or other similar recapitalization with respect to the common stock), in a firm-commitment underwritten public offering pursuant to an effective registration statement under the Securities Act of 1933, as amended, resulting in at least $50,000,000 of gross proceeds to the Corporation and in connection with such offering the common stock is listed for trading on the Nasdaq Stock Market’s National Market, the New York Stock Exchange or another exchange or marketplace approved the Board or (b) the affirmative vote or written consent of the majority preferred stockholders. All outstanding convertible preferred stock was converted into common stock immediately prior to the closing of the Company's IPO.

Liquidation preference

In the event of any voluntary or involuntary liquidation, dissolution or winding up of the Company, the holders of shares of Series A, Series B and Series C Convertible Preferred Stock then outstanding would have been entitled to be paid out of the assets of the Company available for distribution to its stockholders, and in the event of a Deemed Liquidation Event (as defined in the Company’s Charter), the holders of shares of Series A, Series B and Series C Convertible Preferred Stock then outstanding would have been entitled to be paid out of the consideration payable to stockholders in such Deemed Liquidation Event or out of the available proceeds, as applicable, before any payment shall be made to the holders of common stock by reason of their ownership thereof, an amount per share equal to the greater of (i) the Series A, Series B and Series C Convertible Preferred Stock original issue prices, plus any dividends declared but unpaid thereon, or (ii) such amount per share as would have been payable had all shares of Series A, Series B and Series C Convertible Preferred Stock been converted into common stock immediately prior to such liquidation, dissolution, winding up or Deemed Liquidation Event.

11.

Common stock

On August 30, 2024, the Company’s stockholders approved the fourth amended and restated certificate of incorporation, which was filed upon the closing of the IPO on September 16, 2024, and which, among other things, increased the number of shares of common stock authorized for issuance to 500,000,000 shares of common stock, $0.0001 par value.

On September 16, 2024, the Company completed the IPO of its common stock and issued and sold 11,730,000 shares of its common stock at a price of $16.00 per share. As a result, the Company received $170.5 million in net proceeds, after deducting underwriting discounts and commissions and offering costs of $17.2 million.

On September 26, 2025, the Company completed the September 2025 Offering and issued and sold 11,108,055 shares of its common stock at a price of $18.00 per share. As a result, the Company received $187.4 million in net proceeds, after deducting underwriting discounts and commissions and offering costs of $12.5 million.

As of December 31, 2025, and December 31, 2024, there were 44,927,953 and 33,421,525 shares of common stock issued and outstanding, respectively. Shares of common stock issued and outstanding as of December 31, 2025, include 694 shares of restricted stock related to the unvested portion of early exercised common stock options. Shares of common stock issued and outstanding as of December 31, 2024 include 12,608 shares of restricted stock related to the unvested portion of early exercised common stock options. These are included in shares of common stock as they are considered to be legally outstanding as of December 31, 2025, and December 31, 2024, respectively. These shares are subject to the Company’s option to repurchase and are not transferrable until such time as they are fully vested.

F-18

Common stock reserved

The number of shares of common stock that have been reserved for future issuance in connection with outstanding stock options granted under the Company's 2019 Stock Option and Grant Plan (the "2019 Plan") and the 2024 Stock Option and Incentive Plan (the "2024 Plan"), stock options available for grant under the 2019 Plan and 2024 Plan and shares available for future issuance under the Company's 2024 Employee Stock Purchase Plan (the "2024 ESPP") as of December 31, 2025 and December 31, 2024, are as follows:

December 31,

12.

Stock-Based Compensation

2019 Stock Option and Grant Plan ("2019 Plan")

The Company’s 2019 Plan, as amended, provides for the Company to sell or issue common stock or restricted common stock or to grant incentive stock options or nonqualified stock options for the purchase of common stock, to employees, members of the Board, and consultants of the Company. The 2019 Plan is administered by the Board or at the discretion of the Board by a committee of the Board. The exercise prices, vesting periods, and other restrictions are determined at the discretion of the Board or a committee of the Board, except that the exercise price per share of stock options may not be less than 100% of the fair market value of the share of common stock on the date of grant and the contractual term of stock option may not be greater than 10 years. Stock options granted to date typically vest and become exercisable over four years from the date of grant.

As of the date the 2024 Plan became effective, there will be no further awards granted under the 2019 Plan, but all outstanding awards under the 2019 Plan will continue to be governed by their existing terms. 2,458,082 stock options to purchase common stock were outstanding under the 2019 Plan as of December 31, 2025.

2024 Stock Option and Incentive Plan ("2024 Plan")

In August 2024, the Company's board of directors adopted, and its stockholders approved, the 2024 Plan, which became effective in September 2024. The 2024 Plan allows the Company to make equity-based and cash-based incentive awards to its officers, employees, directors and consultants. The 2024 Plan provides for the grant of incentive stock options, stock options, stock appreciation rights, restricted shares of common stock, restricted stock units, dividend equivalent rights and cash bonuses. The number of shares initially reserved for issuance under the 2024 Plan is 3,065,000 shares. In addition, the number of shares reserved and available for issuance under the 2024 Plan will automatically increase on January 1, 2025 and each January 1 thereafter, by five percent (5%) of the sum of the outstanding number of shares of common stock and the numbers of shares of common stock issuable pursuant to the exercise of any outstanding warrants to acquire common stock for a nominal exercise price on the immediately preceding December 31 or such lesser number of shares as determined by the compensation committee. The number of shares reserved under the 2024 Plan is subject to adjustment in the event of a stock split, stock dividend or other change in our capitalization. As of December 31, 2025, 2,174,566 stock options to purchase common stock were outstanding under the 2024 Plan and 2,745,748 shares remained available for future grant under the 2024 Plan. The shares available for issuance under the 2024 Plan may be authorized but unissued shares or shares reacquired by the Company.

The shares of common stock underlying any awards under the 2024 Plan and the 2019 Plan that are forfeited, cancelled, held back upon exercise or settlement of an award to satisfy the exercise price or tax withholding, reacquired by the Company prior to vesting, satisfied without the issuance of stock, expire or are otherwise terminated (other than by exercise) will be added back to the shares of common stock available for issuance under the 2024 Plan.

2024 Employee Stock Purchase Plan ("2024 ESPP")

In August 2024, the Company's board of directors adopted, and its stockholders approved, the 2024 ESPP, which became effective in September 2024. A total of 289,436 shares of common stock were initially reserved for issuance under the 2024 ESPP. The 2024 ESPP provides that the number of shares reserved and available for issuance will automatically increase on January 1, 2025 and each January 1 thereafter, by the least of (i) 578,872 shares of common stock, (ii) one percent (1%) of the

F-19

number of shares of common stock issued and outstanding on the immediately preceding December 31, or (iii) such lesser number of shares of common stock as determined by the administrator of the 2024 ESPP. The number of shares reserved under the 2024 ESPP is subject to adjustment in the event of a stock split, stock dividend or other change in our capitalization. As of December 31, 2025, 623,651 shares remained available for issuance under the 2024 ESPP. No shares were issued under the 2024 ESPP during the years ended December 31, 2025 and 2024.

Stock option valuation

The determination of the grant date fair value of stock-based awards granted to employees, directors and nonemployees during the years ended December 31, 2025, and 2024, is estimated using the Black-Scholes option-pricing model and was calculated based on the following assumptions.

Years ended December 31,

MBX US Equity

MBX · 10-K · period ended 2025-12-31

Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations.

Item 7A. Quantitative and Qualitative Disclosures About Market Risk.

Item 8. Financial Statements and Supplementary Data.

Item 9. Changes in and Disagreements With Accountants on Accounting and Financial Disclosure.

Item 9A. Controls and Procedures.

Item 9B. Other Information.

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections.

Item 10. Directors, Executive Officers and Corporate Governance.

Item 11. Executive Compensation.

Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters.

Item 13. Certain Relationships and Related Transactions, and Director Independence.

Item 14. Principal Accounting Fees and Services.

Item 15. Exhibits, Financial Statement Schedules.

Item 16. Form 10-K Summary

MBX US Equity☆

MBX · 10-K · period ended 2025-12-31

Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations.

Item 7A. Quantitative and Qualitative Disclosures About Market Risk.

Item 8. Financial Statements and Supplementary Data.

Item 9. Changes in and Disagreements With Accountants on Accounting and Financial Disclosure.

Item 9A. Controls and Procedures.

Item 9B. Other Information.

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections.

Item 10. Directors, Executive Officers and Corporate Governance.

Item 11. Executive Compensation.

Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters.

Item 13. Certain Relationships and Related Transactions, and Director Independence.

Item 14. Principal Accounting Fees and Services.

Item 15. Exhibits, Financial Statement Schedules.

Item 16. Form 10-K Summary

MBX US Equity