MBX 10-K & 10-Q changes, risk factors and insider trading

Since inception, we have incurred significant operating losses. Our net loss was $61.9$87.0 million and $32.6$61.9 million for the years ended December 31, 20242025 and December 31, 2023,2024, respectively. As of December 31, 2024,2025, we had an accumulated deficit of $137.5$224.5 million. We have financed our operations primarily through our issuance and sale of our common stock, including through the sale of common stock in our initial and secondary public offerings and sales of our common stock from time to time in “at-the-market” offerings, convertible preferred stock and convertible promissory notes. Substantially all of our losses have resulted from expenses incurred in connection with our research and development and from general and administrative costs associated with our operations. We expect to continue to incur significant expenses and increasing operating 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 our current product candidates and potential future product candidates. The net losses we incur may fluctuate significantly from quarter to quarter. We anticipate that our expenses will increase substantially for the foreseeable future if and as we:

As of December 31, 2024,2025, our cash, cash equivalents and marketable securities were $262.1$373.7 million. We expect that our existing cash, cash equivalents, and marketable securities will enable us to fund our operating expenses and capital expenditure requirements into mid-2027.2029. However, our operating plan may change as a result of factors currently unknown to us, and we may need to seek funding sooner than planned. Our future capital requirements will depend on many factors, including:

We are an early-stage company. We commenced our operations in August 2018. Our operations to date have been limited to organizing and staffing our company, business planning, raising capital, and research and development activities such as developing our platform and technology and identifying and beginning to advance preclinical and clinical testing of our product candidates. TwoThree of our product candidates, canvuparatidecanvuparatide, (MBX 2109)imapextide and MBX 14164291 are in clinical development, while MBX 4291 has recently completed IND-enabling studies and our other development programs in our obesity portfolio remain in the research or lead optimization stage of development. We have not yet demonstrated an ability to complete any large-scale, pivotal clinical trials, advance any product candidate beyond Phase 2, obtain regulatory approvals, manufacture our product candidates at commercial scale, arrange for a third party to do so on our behalf or conduct sales and marketing activities necessary for successful commercialization.

We are in the early stages of our development efforts and have only twothree product candidates, canvuparatide (MBX 2109), imapextide (MBX 1416), and MBX 1416,4291 in clinical development, and one product candidate that has completed IND-enabling studies. All of our other development programs are stillremain in the preclinicalresearch or druglead discoveryoptimization stage.stage of development. To date, as an organization, we have not completed the development of any product candidates. Our future success and ability to generate revenue from our product candidates is dependent on our ability to successfully develop, obtain regulatory approval for and commercialize one or more of our product candidates. All of our product candidates will require substantial additional investment for clinical development, regulatory review and approval in one or more jurisdictions. If any of our product candidates encounters safety or efficacy problems, development delays or regulatory issues or other problems, our development plans and business would be materially harmed.

Although the development and commercialization of canvuparatide, MBX 1416imapextide and MBX 4291 and the other development candidates in our obesity portfolio are our initial focus, as part of our longer-term growth strategy, we plan to continue to develop our additional assets in earlier stages of development and to build fully functional internal discovery capabilities to develop other product candidates. We intend to evaluate internal opportunities from our existing product candidates or other potential product candidates. We have historically relied on the discovery capabilities of our co-founder, Dr. Richard DiMarchi. Dr. DiMarchi is a current consultant to the Company, as well as the principal investigator under our research agreement with the Trustees of Indiana University, under which we retain intellectual property developed on our behalf by Dr. DiMarchi, but the consulting agreement and research agreement are both terminable by either party. We are continuing to expand our laboratory capabilities and expect to continue to enhance our internal discovery efforts. If we are unable to complete this internalization, we may not be able to add internally-developed product candidates to our pipeline and will have to rely on our existing product candidates, additional product candidates we may in-license, or additional candidates we may develop through third-party research partners.

clinical trial results may show the product candidates to be less effective than expected (for example, a clinical trial could fail to meet its primary or key secondary endpoint(s)) or have an unacceptable safety or tolerability profile or may not show an appropriate dose to fit a target profile, or may not be consistent with our pharmacokinetic modeling;

Our failure to successfully initiate and complete clinical trials and to demonstrate the efficacy and safety necessary to obtain regulatory approval to market our product candidates would significantly harm our business. Our product candidate development costs will also increase if we experience delays in testing or regulatory approvals and we may be required to obtain additional funds to complete clinical trials. We cannot be certain that our clinical trials will begin as planned or be completed on schedule, if at all, or that we will not need to restructure or otherwise modify our trials after they have begun. For instance, we havepreviously adjusted our protocol for canvuparatideour Phase 2 trial to take into account feedback from our CRO. Significant clinical trial delays also could shorten any periods during which we may have the exclusive right to commercialize our product candidates or allow our competitors to bring products to market before we do and impair our ability to successfully commercialize our product candidates, which may harm our business and results of operations. In addition, many of the factors that cause, or lead to, delays of clinical trials may ultimately lead to the denial of regulatory approval of our product candidates.

Undesirable side effects caused by any of our product candidates could cause us or regulatory authorities to interrupt, delay or halt clinical trials and could result in a more restrictive label or the delay or denial of regulatory approval by the FDA or comparable foreign regulatory authorities. Certain side effects have been observed in our product candidates to date. For example, injection site reactions were commonly observed in subjects dosed with MBX 1416imapextide in the single and multiple ascending dose cohorts of our Phase 1 trial of MBX 1416.imapextide. Although MBX 1416imapextide was generally well-tolerated, these ISRs were mostly mild to moderate, and PBH is a severe orphan disease with no FDA approved treatment options, if we are unable to identify a dose of MBX 1416imapextide with a tolerable side-effect profile, the commercial success of MBX 1416,imapextide, if approved, could be limited. In addition, in our Phase 1 clinical trial of canvuparatide, the most common treatment-related adverse events observed were injection site reactions, though these were infrequent, less than 5 cm in size, and similar to those seen in other PTH agents, and we observed events of hypercalcemia at the top doses in three subjects each in the single and multiple ascending dose cohort. We also anticipate that, inIn our Avail trial in patients with HP, because patients are randomized into three dose levels while study investigators are reducing active vitamin D and calcium supplements and identifying an appropriate dose level based on a titration algorithm, we mayalso observe someobserved incidents of hypocalcemia in four patients and hypercalcemia.hypercalcemia in nine patients. If we are unable to identify a dose of canvuparatide, or any of our other potential candidates with a tolerable side-effect profile, or are limited in our ability for our product candidates to be used with certain other drugs, the commercial success of such product candidates, if approved, could be limited.

As we progress our programs, we may not be able to initiate or continue clinical trials for our product candidates if we are unable to locate and enroll a sufficient number of eligible patients to participate in these trials as required by the FDA or other comparable regulatory authorities outside the United States, or as needed to provide appropriate statistical power for a given trial. Enrollment may be particularly challenging for some of the rare diseases we are targeting in our programs such as canvuparatide and MBX 1416.imapextide. For instance, in our Phase 1 trial of canvuparatide, we added one new site to the trial following slow enrollment at the originally selected sites, in order to meet our enrollment requirements. Enrollment may also be challenging for product candidates targeting prevalent diseases, such as MBX 4291 or other product candidates in our obesity portfolio, due to the intense competition in the field. In addition, if patients are unwilling to participate in our trials because of negative publicity from adverse events, competitive clinical trials for similar patient populations, clinical trials in competing product candidates, commercially available competing products or for other reasons, the timeline for recruiting patients, conducting studies and obtaining regulatory approval of our product candidates may be delayed. Moreover, some of our competitors may have commercially available products, such as Yorvipath, or ongoing clinical trials for product candidates, such as AstraZeneca’s PTH analog, AZP-3601, that would treat the same indications as our product candidates, and patients who would otherwise be eligible for our future clinical trials may instead utilize competitors’ approved products or enroll in clinical trials of our competitors’ product candidates.

In addition, if we are unable to enroll a sufficient number of eligible patients in these trials in the United States, we may lookexpect to enroll in sites outside of the United States. Our ability to successfully initiate, enroll and complete a clinical trial in any foreign country is subject to numerous risks unique to conducting business in foreign countries, some of which may include:

Due to the significant resources required for the development of our product candidates, we must decide which product candidates and indications to pursue and advance and the amount of resources to allocate to each. Our decisions concerning the allocation of research, development, collaboration, management and financial resources toward particular product candidates, therapeutic areas or indications may not lead to the development of viable commercial products and may divert resources away from better opportunities. For instance, we have elected to evaluate MBX 1416imapextide as a treatment for PBH, but there may be better indications for which to evaluate MBX 1416,imapextide, and this decision may divert resources away from better opportunities for MBX 1416.imapextide. If we make incorrect determinations regarding the viability or market potential of any of our product candidates or misread trends in the pharmaceutical industry, in particular for the rare diseases we are pursuing, our business, financial condition and results of operations could be materially and adversely affected. As a result, we may fail to capitalize on viable commercial products or profitable market opportunities, be required to forego or delay pursuit of opportunities with other product candidates or other diseases and disease pathways that may later prove to have greater commercial potential than those we choose to pursue, or relinquish valuable rights to such product candidates through collaboration, licensing or royalty arrangements in cases in which it would have been advantageous for us to invest additional resources to retain sole development and commercialization rights.

In addition, a product known as Yorvipath has received orphan medicine designation for hypoparathyroidism in the EU and was granted a marketing authorization in November 2023. In the EU, orphan medicines benefit from 10 years of market exclusivity once they receive a marketing authorization in the EU (which may be extended by two additional years when the results of specific studies are reflected in the summary of product characteristics ("SmPC") addressing the paediatricpediatric population and completed in accordance with a fully compliant paediatricpediatric investigation plan). This market exclusivity prevents the EMA and all EU Member States from accepting an application or granting a marketing authorization for a “similar medicinal product” for the same therapeutic indication as the authorized orphan medicine, subject to certain specific derogations. Regulation (EC) 847/2000 defines a “similar medicinal product” as one which contains a similar active substance or substances as contained in an authorized orphan medicinal product and which is intended for the same therapeutic indication. A “similar active substance” is defined in the same Regulation as an identical active substance, or an active substance with the same principal molecular structural features (but not necessarily all of the same molecular structural features) and which acts via the same mechanism. There are some limited derogations to the market exclusivity granted to orphan medicinal products in the EU. Specifically, a company may be able to market a similar medicinal product to an authorized orphan product if: (i) the marketing authorization holder for the authorized orphan product consents to the grant of a marketing authorization for the similar product; (ii) the marketing authorization holder for the authorized orphan product is unable to supply sufficient quantities of its product; or (iii) the later applicant can establish that its product, although similar to the authorized orphan product, is safer, more effective or otherwise clinically superior. Regulation (EC) 847/2000 provides details on what would constitute clinical superiority in this context, including that direct comparative clinical trials may be required to demonstrate greater efficacy or safety to the authorized orphan product. As a result, while we have secured orphan drug designation in Europe, this still needs to be converted to orphan drug status at the time of a marketing authorization application, and we may not be able to gain approval for canvuparatide in the EU until expiry of the market exclusivity period for Yorvipath (palopegteriparatide) (which could run until 2035 at the latest), unless we can demonstrate that canvuparatide is either not a similar medicinal product to Yorvipath (i.e. the active substance in canvuparatide, if not identical to Yorvipath, does not have the same principal molecular structural features and act via the same mechanism as Yorvipath) or, if it is, that canvuparatide is safer, more effective or otherwise clinically superior. Any comparative studies required to demonstrate clinical superiority could be costly and time-consuming, and there is no certainty that we would succeed in adequately demonstrating that our product is clinically superior to Yorvipath.

Our current and future product candidates could fail to receivereceive, or be significantly delayed in receiving, regulatory approval for many reasons, including the following:

Our product candidates are sensitive to temperature, storage and handling conditions. They must be stored at very low temperatures in specialized freezersfreezers, refrigerators or specialized shipping containers until immediately prior to use. The handling and administration of the therapy product, if approved, may need to be performed according to specific instructions and in some steps within specific time periods. Failure to correctly handle our product could negatively impact the efficacy and or safety of our product, or cause a loss of product. In addition, if approved, certain of our products may need to be frozen or refrigerated using specialized equipment and maintained following specific procedures in order to be stored without damage in a cost-efficient manner and without degradation. We will need to scale-up a cost-effective and reliable cold-chain distribution and logistics network, which we may be unable to accomplish. Failure to effectively scale-up our cold-chain supply logistics, by us or third parties, could in the future lead to additional manufacturing costs and delays in our ability to supply required quantities for commercial supply. For these and other reasons, we may not be able to manufacture our current or future product candidates at commercial scale or in a cost-effective manner. Even if we are able to manufacture and distribute the product candidates, if our products require specific procedures to maintain and use them, we may be limited in commercial opportunity.

The general approach for FDA approval of a new drugdrug, isat least until recently, has been dispositive data from two or more adequate and well-controlled clinical trials of the product candidate in the relevant patient population. AdequateWhile the FDA has recently announced one adequate and well-controlledcontrolled clinicaltrial may be acceptable to support an NDA, these trials typically involve a large number of patients, have significant costs and take years to complete.complete and will still need to be supported by other appropriate data as part of any future NDA. The FDA or other regulatory authorities may disagree with us about whether a clinical trial is adequate and well-controlled or may request that we conduct additional clinical trials prior to regulatory approval. In addition, there is no assurance that the doses, endpoints and trial designs that we intend to use for our planned clinical trials, including those that we have developed based on feedback from regulatory agencies or those that have been used for the approval of similar drugs, will be acceptable for future approvals.

We may in the future choose to conduct one or more additional clinical trials outside the United States, including, among other places, in the EU, South America, Australia and/or Asia. The acceptance of study data from clinical trials conducted outside the United States or another jurisdiction by the FDA or comparable foreign regulatory authority may be subject to certain conditions or may not be accepted at all. In cases where data from foreign clinical trials are intended to serve as the basis for regulatory approval in the United States, the FDA will generally not approve the application based on foreign data alone unless: (i) the data is applicable to the U.S. population and U.S. medical practice; and (ii) the trials were performed by clinical investigators of recognized competence and pursuant to GCP regulations. Additionally, the FDA’s clinical trial requirements, including sufficient size of patient populations and statistical powering, must be met. Many foreign regulatory authorities have similar approval requirements. In addition, such foreign trials would be subject to the applicable local laws of the foreign jurisdictions where the trials are conducted. There can be no assurance that the FDA or any comparable foreign regulatory authority will accept data from trials conducted outside of the United States or the applicable jurisdiction. If the FDA or any comparable foreign regulatory authority does not accept such data, it would result in the need for additional trials, which could be costly and time-consuming, and which may result in drug candidates that we may develop not receiving approval for commercialization in such jurisdiction. Additionally, recent policy proposals in the U.S., if enacted in the future, may make acceptance by the FDA or inclusion in a marketing application of foreign data more difficult or costly.

Similarly, in the EU, the European Commission ("EC") grants orphan medicinal product designation after receiving the opinion of the EMA’s Committee for Orphan Medicinal Products on an orphan medicinal product designation application. Orphan medicinal product designation may be granted in respect of medicinal products that are intended for the diagnosis, prevention or treatment of life threatening or chronically debilitating conditions affecting not more than five (5) in ten thousand (10,000) persons in the EU or for products intended for the diagnosis, prevention, or treatment of a life threatening, seriously debilitating or serious and chronic condition when, without incentives, it is unlikely that sales of the product in the EU would generate sufficient return to justify the necessary investment in developing the product. In each case, there must be no satisfactory method of diagnosis, prevention, or treatment authorized for marketing in the EU (or, if such a method exists, the product would be of significant benefit to those affected by the condition). In the EU, orphan medicinal product designation entitles a party to financial incentives such as reduction of fees or fee waivers.

Generally, if a drug with an Orphan Drug Designation subsequently receives the first marketing approval for the indication for which it has such designation, the drug is entitled to a period of marketing exclusivity, which precludes the EC or the competent authorities of the EU member states, or the FDA from approving another marketing application for the same drug and indication for that time period, except in limited circumstances. The applicable period is seven years in the U.S. and ten years in the EU. The EU exclusivity period can be reduced to six years if a drug no longer meets the criteria for orphan medicinal product designation or if the drug is sufficiently profitable so that market exclusivity is no longer justified.

The ability of the FDA to review and approve new products can be affected by a variety of factors, including government budget and funding levels, ability to hire and retain key personnel and accept the payment of user fees, and statutory, regulatory, and policy changes. Average review times at the agency have fluctuated in recent years as a result. In addition, government funding of other government agencies on which our operations may rely, including those that fund research and development activities, is subject to the political process, which is inherently fluid and unpredictable. Disruptions at the FDA or other government agencies may also slow the time necessary for new drugs to be reviewed and/or approved by necessary government agencies, which would adversely affect our business. For example, over the last several years, the U.S. government has shut down several times and certain regulatory agencies, such as the FDA, have had to furlough critical employees and stop critical activities. If a prolonged government shutdown occurs, including as a result of reaching the debt ceiling, it could significantly impact the ability of the FDA to timely review and process our regulatory submissions, which could have a material adverse effect on our business. Further, future government shutdowns could impact our ability to access the public markets and obtain necessary capital in order to properly capitalize and continue our operations.

Any regulatory approvals that we receive for our product candidates may be subject to limitations on the approved indicated uses for which the product may be marketed or to the conditions of approval, or contain requirements for potentially costly post-marketing testing, including Phase 4 clinical trials and surveillance to monitor the safety and efficacy of the product candidate. Certain endpoint data we hope to include in any approved product labeling also may not make it into such labeling, including exploratory or secondary endpoint data such as patient-reported outcome measures. The FDA may also require a risk evaluation and mitigation strategies,strategies or REMS,("REMS") program as a condition of approval of our product candidates, which could entail requirements for long-term patient follow-up, a medication guide, physician communication plans or additional elements to ensure safe use, such as restricted distribution methods, patient registries and other risk minimization tools. In addition, if the FDA or a comparable foreign regulatory authority approves our product candidates, we will have to comply with requirements including submissions of safety and other post-marketing information and reports and registration.

Our internal computer and information technology systems, or those of our third-party vendors, collaborators, contractors, consultants or other third parties, may fail, become unavailable, or suffer securitycybersecurity incidents, compromises, or data breaches, loss or leakage of data and other disruptions, which could result in a material disruption of our product development programs, compromise confidential, sensitive or personal information related to our business or prevent us from accessing critical information, potentially exposing us to liability or otherwise adversely affecting our business.

Our internal computer and information technology systems and those of our current and any future third-party vendors, collaborators, contractors, consultants or other third parties, are vulnerable to damage or interruption from, among other things, computer viruses, computer hackers, social engineering (including phishing attacks,attacks), attacks enhanced or facilitated by AI, ransomware, malware, social engineering, service interruptions, system malfunction, malicious code, employee theft, fraud, misconduct or misuse, wrongful conduct by insider employees or vendors, denial-of-service attacks, sophisticated nation-state and nation-state-supported actors, data breaches, unauthorized access, natural disasters, terrorism, war and telecommunication and electrical failures. While we seek to protect our information technology systems from system failure, accident and security breach, we have in the past and may in the future experience phishing and other security incidents which could result in a disruption of our development programs and our business operations, whether due to a loss of our trade secrets or other proprietary, personal or confidential information or other disruptions. For example, the loss of clinical trial data from future clinical trials could result in delays in our regulatory approval efforts and significantly increase our costs to recover or reproduce the data.

If we were to experience a cybersecurity incident, breach, compromise or other security event relating to our information systems or data, the costs, time and effort associated with the investigation, remediation and potential notification of the breach to counterparties, regulators and data subjects could be material. We may incur significant costs in an effort to detect and prevent security incidents or compromises, and we may face increased costs and requirements to expend substantial resources in the event of an actual or perceived security incident or compromise. In addition, techniques used to sabotage or to obtain unauthorized access to networks in which data is stored or through which data is transmitted change frequently, become more complex over time and generally are not recognized until launched against a target. The risk of a cybersecurity breach, incident, compromise or disruption, particularly through cyberattacks including supply chain attacks or cyber intrusion, including by computer hackers, foreign governments, and cyber terrorists, has generally increased as the number, intensity, and sophistication of attempted attacks and intrusions from around the world have increased. Attempts to disrupt or gain unauthorized access to our and our third-party service providers’ information systems from malicious third parties or insider threats may incorporate widely varying and frequently changing tactics, which may be enhanced or facilitated by AI. As a result, we and our third-party vendors may be unable to anticipate these techniques or implement adequate preventative measures quickly enough to prevent either an electronic intrusion into our systems or services or a compromise of critical information. We cannot guarantee that we will be able to detect or prevent any such incidents, and, our remediation efforts may not be successful or timely. Our efforts to improve our cybersecurity and protect data from compromise may also identify previously undiscovered instances of data breaches, compromises or other cybersecurity incidents. If we do not allocate and effectively manage the resources necessary to build and sustain the proper technology and cybersecurity infrastructure, we could suffer significant business disruption, including transaction errors, supply chain or manufacturing interruptions, processing inefficiencies, data loss or the loss of or damage to intellectual property or other proprietary, personal or confidential information. Our contracts may not contain limitations of liability, and even where they do, there can be no assurance that limitations of liability in our contracts are sufficient to protect us from liabilities, damages, or claims related to our privacy and data security obligations. Although we currently maintain cybersecurity insurance, the insurance we maintain against the risk of this type of loss may not be sufficient to cover actual losses, or may not apply to the circumstances relating to any particular loss.

To the extent that any disruption or security breach were to result in a loss of, or damage to, our or our third-party vendors’, collaborators’, contractors’, employees’, consultants’ or other third parties’ data, including personal data, or applications or inappropriate disclosure, loss, destruction or alteration of, or access to, confidential, personal or proprietary information, we could incur significant liability including litigation exposure, substantial penalties and fines, we could become the subject of regulatory action, inquiry or investigation, our competitive position could be harmed, we could incur significant reputational damage and the further development and commercialization of any product candidates we may develop could be delayed. Any of the above could have a material adverse effect on our business, financial condition, results of operations or prospects.

We are subject to data privacy and protection laws, rules, regulations, policies, standards and contractual obligations that apply to the collection, transmission, storage, use, disclosure, transfer, maintenance and other processing of sensitive, personal and personally-identifying information, which, among other things, impose certain requirements relating to the privacy, security, transmission and other processing of personal information. The legislative and regulatory landscape for privacy and data protection continues to evolve in jurisdictions worldwide, and there has been an increasing focus on privacy and data protection issues with the potential to affect our business. However, our data privacy program is in its early stages and we have not yet assessed the applicability of and our compliance with data privacy-related laws, rules and regulations. As a result, we cannot guarantee that we are and have been in compliance with all applicable data privacy and protection laws, rules, regulations, policies and standards, and we may need to expend significant resources to implement privacy compliance measures. Additionally, we rely on certain third-party vendors to process certain confidential, sensitive or personal information on our behalf. Failure by us or our third-party vendors to comply with any of these laws, rules, regulations, contractual obligations or standards could result in notification obligations, enforcement actions, regulatory investigations or inquiries, significant fines, imprisonment of company officials and public censure, litigation and claims for damages by affected individuals, customers or business partners, damage to our reputation and loss of goodwill, any of which could have a material adverse effect on our business, financial condition, results of operations or prospects.

There are numerous U.S. federal and state laws, rules and regulations related to the privacy and security of personal information. In particular, regulations promulgated pursuant to the Health Insurance Portability and Accountability Act of 1996 ("HIPAA") establish privacy and security standards that limit the use and disclosure of individually identifiable health information, or protected health information, and require the implementation of administrative, physical and technological safeguards to protect the privacy of protected health information and ensure the confidentiality, integrity and availability of electronic protected health information. The Genetic Information Nondiscrimination Act of 2008 ("GINA") clarified that genetic information is protected under HIPAA and restricts the use and disclosure of genetic information. Even when HIPAA does not apply, according to the Federal Trade Commission (“FTC”), failing to take appropriate steps to keep consumers’ personal information secure constitutes unfair acts or practices in or affecting commerce in violation of Section 5(a) of the Federal Trade Commission Act. The FTC’s current guidance for appropriately securing consumers’ personal information is similar to what is required by the HIPAA security regulations, but this guidance may change in the future, resulting in increased complexity and the need to expend additional resources to ensure we are complying with the FTC Act.

Data privacy remains an evolving landscape at both the domestic and international level, with new laws, rules and regulations coming into effect and continued legal challenges. At the state level, numerous states have enacted or are in the process of enacting or considering comprehensive data privacy and security laws, rules and regulations while other states have focused on more narrow aspects of privacy. For example, in California, the California Consumer Privacy Act, or CCPA, which came into effect on January 1, 2020, established a comprehensive privacy framework for covered businesses by creating an expanded definition of personal information, providing new data privacy rights for consumers and imposing new operational requirements for companies. The CCPA requiredrequires covered companies to provide certain disclosures to consumers about their data collection, use and sharing practices, and to provide affected California residents with ways to opt-out of certain sales or transfers of personal information. In particular, the CCPA gavegives California residents expanded rights to access and delete their personal information, opt out of certain personal information sharing, and to receive detailed information about how their personal information is used. Laws similar to the CCPA have been passed or proposed in numerous other states, including Colorado, Virginia, Utah, Connecticut, New Jersey, New Hampshire and more. Such laws addadding complexity, varyvarying requirements, restrictions and potential legal risk, requireand requiring additional investment of resources in compliance programs,programs. The introduction of these laws across the country may impact strategies and the availability of previously useful data and could result in increased compliance costs and/or changes in business practices and policies.

Several states are also specifically regulating health information. For example, Washington state passed a health privacy law that will regulate the collection and sharing of consumer health information, and the law also has a private right of action, which further increases the relevant compliance risk. Connecticut and Nevada have also passed similar laws regulating consumer health data, and a similar law is awaiting the governor’s signature in New York.data. In addition, other states have proposed and/or passed legislation that regulates the privacy and/or security of certain specific types of information. For example, a number of statesstates, including Illinois and Texas, have passed laws that regulate biometric data specifically. These various privacy and security laws may impact our business activities, including our identification of research subjects, relationships with business partners and ultimately the marketing and distribution of our products. State laws are changing rapidly and there ishave discussionbeen discussions in the U.S. Congress of comprehensive federal data privacy laws to which we could become subject, if enacted. The existence of different privacy laws in various jurisdictions in the country would make our compliance obligations more complex and costly and may increase the likelihood that we may be subject to enforcement actions or otherwise incur liability for noncompliance. Although many of the existing state privacy laws exempt clinical trial information and health information governed by HIPAA, future privacy and data protection laws may be broader in scope.

Regulators and legislators in the U.S. are also increasingly scrutinizing and restricting certain personal data transfers and transactions involving foreign countries. For example, Executivethe Order 1147Department of FebruaryJustice’s 28,January 2024,8, 2025, rule on “Preventing Access to Americans’ BulkU.S. Sensitive Personal Data and United States Government-Related Data by Countries of Concern or Covered Persons,” as implemented by Department of Justice regulations issued in December 2024, prohibits data brokerage and data sharing transactions involving certain sensitive personal data categories, including health data, genetic data, and biospecimens, to countries of concern, including China. The regulations also restrict certain investment agreements, employment agreements and vendor agreements involving such data and countries of concern, absent specified cybersecurity controls. Actual or alleged violations of these regulations may be punishable by criminal and/or civil sanctions, and may result in exclusion from participation in federal and state programs.

We may choose to integrate AI into our operations,operations both in our own development and implementation of AI and through the adoption of commercially available tools, and this innovation presents risks and challenges that could affect its adoption, and therefore our business. There are significant risks involved in utilizing AI and no assurance can be provided that the usage of AI will enhance our business or assist our business in becoming more efficient or profitable. The use of certain AI technology can give rise to intellectual property risks, including compromisesby todisclosing or otherwise compromising our confidential or proprietary intellectual property and intellectual property infringement and misappropriation.misappropriation, Otheror knownby risksundermining our ability to assert or defend ownership rights in intellectual property created with the assistance of AI currentlytools. includeDevelopment, inaccuracy,use, and deployment of these technologies could pose cybersecurity, data privacy, IT, intellectual property, regulatory, legal, operational, competitive, reputational, and other risks and challenges that could affect our business. Specifically, risks related to bias, toxicity,AI hallucinations, discrimination, harmful content, misinformation, fraud, scams, targeted attacks such as model poisoning or data privacypoisoning, surveillance, data leakage, loss of consensus reality, inequality, environmental harms, and cybersecurityother issues,harms andmay dataflow provenancefrom disputes.our development, use, or deployment of AI technologies. In addition, AI may have errors or inadequacies that are not easily detectable. AI may also be subject to data herding and interconnectedness (i.e., multiple market participants utilizing the same data), which may adversely impact our business. If the data used to train AI or the content, analyses, or recommendations that AI applications assist in producing are or are alleged to be deficient, inaccurate, incomplete, overbroad or biased, our business, financial condition, and results of operations may be adversely affected.

A growing number of legislators and regulators are adopting laws and regulations and have focused enforcement efforts on the adoption of AI, and use of such technologies in compliance with ethical standards and societal expectations. These developments may increase our compliance burden and costs in connection with use of artificial intelligence and lead to legal liability if we fail to meet evolving legal standards or if use of such technologies results in harms or other causes of action we did not predict. For example, the EU’sEU began implementing the Artificial Intelligence Act ("the “AI Act"”) entered into force on August 1, 2024 and,2024, with somea exceptions,significant willpart becomeof fullythe applicablelaw 24scheduled monthsto thereafter.come Thisinto legislationeffect in August 2026. As currently enacted, the AI Act, which may be amended as part of the EU’s Digital Omnibus, imposes significant obligations on providers and deployers of high risk AI systems, and encourages providers and deployers of AI systems to account for certain ethical principles in their design, development and use of these systems. The scope of requirements depends on legal and risk determinations that rely on novel legal provisions that have not yet been interpreted by courts or regulators, and non-compliance can lead to significant fines. Likewise, in the U.S., several states, including Colorado and California, passed laws that will take effect in 2026, to regulate various uses of artificial intelligence, including to make consequential decisions. In addition, various federal regulators have issued guidance and focused enforcement efforts on the use of AI in regulated sectors. If we develop or use AI systems governed by these laws or regulations, we will need to meet higher standards of data quality, transparency, monitoring and human oversight, and we would need to adhere to specific and potentially burdensome and costly ethical, accountability, and administrative requirements, with the potential for significant enforcement or litigation in the event of any perceived non-compliance.

Our vendors may also incorporate AI tools into their own offerings, and the providers of these AI tools may not meet existing or rapidly evolving regulatory or industry standards, including with respect to intellectual property, privacy and data security. Further, bad actors around the world use increasingly sophisticated methods, including the use of AI, to engage in illegal activities involving the theft and misuse of personal information, confidential information and intellectual property. In addition, the use of generative AI models in our internal or third-party systems may create new attack surfaces or methods for adversaries, which could impact us and our vendors. Any of these effects could damage our reputation, result in the loss of valuable property and information, cause us to breach applicable laws and regulations, and adversely impact our business.

The advancement of our product candidates and development programs and the potential commercialization of our current and future product candidates will require substantial additional cash to fund expenses. For some of our programs, we may decide to collaborate with other pharmaceutical and biotechnology companies with respect to development and potential commercialization. Likely collaborators may include large and mid-size pharmaceutical companies, regional and national pharmaceutical companies and biotechnology companies.companies, and academic research centers. In addition, if we are able to obtain regulatory approval for product candidates from foreign regulatory authorities, we may enter into collaborations with international biotechnology or pharmaceutical companies for the commercialization of such product candidates.

We remain responsible for ensuring that each of our trials is conducted in accordance with the applicable protocol, legal and regulatory requirements and scientific standards. Our failure or the failure of third parties to comply with the applicable protocol, legal and regulatory requirements and scientific standards can result in rejection of our clinical trial data or other sanctions. If we or our third-party clinical trial providers or third-party CROs do not successfully carry out these clinical activities, our clinical trials or the potential regulatory approval of a product candidate may be delayed or be unsuccessful. Additionally, if we or our third-party contractors fail to comply with applicable GCPs, the clinical data generated in our clinical trials may be deemed unreliable and the FDAFDA, or other applicable regulatory agencies, may require us to perform additional clinical trials before approving our product candidates, which would delay the regulatory approval process. We cannot be certain that, upon inspection, the FDA will determine that any of our clinical trials comply with GCPs. We are also required to register certain clinical trials and post the results of completed clinical trials on a government-sponsored database, ClinicalTrials.gov, within certain timeframes. Failure to do so can result in fines, adverse publicity and civil and criminal sanctions.

Additionally, if any third-party manufacturer with whom we contract fails to perform its obligations, we may be forced to manufacture the materials ourselves, for which we may not have the capabilities or resources, or enter into an agreement with a different manufacturer. In either scenario, our clinical trials supply could be delayed significantly as we establish alternative supply sources. In some cases, the technical skills required to manufacture our product candidates may be unique or proprietary to the original manufacturer and we may have difficulty, or there may be contractual restrictions prohibiting us from, transferring such skills to a back-up or alternate supplier, or we may be unable to transfer such skills at all. In addition, if we are required to change third-party manufacturers for any reason, we will be required to verify that the new manufacturer maintains facilities and procedures that comply with quality standards and with all applicable regulations. We will also need to verify, such as through a manufacturing comparability study, that any new manufacturing process will produce our product candidate according to the specifications previously submitted to the FDA or another regulatory authority. We may be unsuccessful in demonstrating the comparability of clinical supplies, which could require the conduct of additional clinical trials. Regional or single-source dependencies may in some cases accentuate these risks. For example, the pharmaceutical industry generally, and in some instances our Company or our collaborators or other third-parties on which we rely, depend on China-based suppliers or services providers for certain raw materials, products and services, or other activities. Our ability or the ability of our collaborators or such other third-parties to continue to engage these China-based suppliers or services providers for certain preclinical research programs and clinical development programs could be restricted due to geopolitical developments between the United States and China, including as a result of the escalation of tariffs or other trade restrictions or ifas thea previouslyresult proposedof federalrecently enacted legislation known aslike the BIOSECURE Act (described below). On December 18, 2025, the National Defense Authorization Act for Fiscal Year 2026 ("NDAA") was enacted, which includes Section 851, commonly referred to as the "BIOSECURE ACT." The BIOSECURE Act restricts U.S. government agencies from procuring biotechnology equipment or services from, or entering into contracts contracting with, entities that use biotechnology equipment or services from, designated "biotechnology companies of concern" ("BCCs"), and from expending federal loans or grant funds for such equipment or services. The enacted version of the BIOSECURE Act does not identify any specific companies by name in the legislative text, but provides for automatic designation as a similarBCC lawif werea tocompany is included on the Department of Defense's Section 1260H list of "Chinese military companies." Companies can also be enacted.designated Theas delaysa associatedBCC withthrough a criteria-based pathway administered through an interagency process led by the verificationOffice of aManagement newand third-partyBudget manufacturer could negatively affect our ability to develop product candidates or commercialize our products in a timely manner or within budget. Furthermore, a third-party manufacturer may possess technology related to the manufacture of our product candidate that such third party owns independently. This would increase our reliance on such third-party manufacturer or require us to obtain a license from such third-party manufacturer in order to have another third party manufacture our product candidates.("OMB").

Our commercial success depends, in large part, on our ability to obtain and maintain intellectual property rights protection through patents, trademarks, and trade secrets in the United States and other countries with respect to our technology and product candidates. If we do not adequately protect our intellectual property rights, competitors or other third parties may be able to erode, negate or preempt any competitive advantage we may have, which could harm our business and ability to achieve profitability. To protect our proprietary position, we have filed patent applications and may file other patent applications in the United States or abroad related to our product candidates that are important to our business; we also license and may purchase patents or patent applications filed by others. In particular, we are heavily reliant on patent rights we have exclusively in-licensed from IURTC pursuant to the IURTC License Agreement. The patent application process is expensive, time-consuming and complex. We may not be able to file, prosecute, maintain, enforce or license all necessary or desirable patent applications at a reasonable cost or in a timely manner. Our owned and in-licensed patent portfolio is generally at a very early stage. In particular, we do not currently own or in-license any issued patents relating to any of our product candidates and we also do not own or in-license any issued U.S. patents relating to our PEP™ technology or otherwise. Further, the only pending patent applications we currently own are two U.S. provisional patent applications relating to one of our product candidates.

It is possible that defects of form in the preparation or filing of our patent portfolio may exist, or may arise in the future, for example with respect to proper priority claims, inventorship, claim scope, or requests for patent term adjustments. If we or our partners, collaborators, or licensees whether current or future, fail to establish, maintain or protect such patents and other intellectual property rights, such rights may be reduced or eliminated. If our partners, collaborators, or licensees are not fully cooperative or disagree with us as to the prosecution, maintenance or enforcement of any patent rights, such patent rights could be compromised. If there are material defects in the form, preparation, prosecution, or enforcement of our patent portfolio, such patents may be invalid and/or unenforceable, and such applications may never result in valid, enforceable patents. Periodic maintenance fees, renewal fees, annuity fees and various other government fees on patents and/or applications will be due to be paid to the USPTO and various government patent agencies outside of the United States over the lifetime of our owned or licensed patents and patent applications. We rely on our outside counsel or our licensing partners to pay these fees due to U.S. and non-U.S. patent agencies. The USPTO and various non-U.S. government patent agencies require compliance with several procedural, documentary, fee payment and other similar provisions during the patent application process. While an inadvertent lapse can, in many cases, be cured by payment of a late fee or by other means in accordance with the applicable rules, there are situations in which non-compliance can result in abandonment or lapse of the patent or patent application, resulting in partial or complete loss of patent rights in the relevant jurisdiction. Non-compliant events that could result in abandonment or lapse of a patent or patent application include, but are not limited to, failure to respond to official actions within prescribed time limits, non-payment of fees and failure to properly legalize and submit formal documents. Any of these outcomes could impair our ability to prevent competition from third parties, which may have an adverse impact on our business.

Although we exclusively in-license pending patent applications relating to our canvuparatide, MBX 1416,imapextide, and MBX 4291 product candidates and we own two pending provisional patent applications relating to our canvuparatidevarious product candidate,candidates, we cannot provide assurances that any of our patent applications will be found to be patentable, including over our own prior art publications or patent literature, or will issue as patents. Neither can we make assurances as to the scope of any claims that may issue from our pending and future patent applications nor to the outcome of any proceedings by any potential third parties that could challenge the patentability, validity or enforceability of our patent portfolio in the United States or foreign jurisdictions. Any such challenge, if successful, could limit patent protection for our product candidates and/or materially harm our business.

In the United States, the Drug Price Competition and Patent Term Restoration Act of 1984 permits a Patent Term Extension,Extension or PTE,("PTE") of up to five years beyond the normal expiration of the patent to compensate patent owners for loss of enforceable patent term due to the lengthy regulatory approval process. A PTE grant cannot extend the remaining term of a patent beyond a total of 14 years from the date of the product approval. Further, PTE may only be applied once per product, and only with respect to an approved indication—in other words, only one patent (for example, covering the product itself, an approved use of said product, or a method of manufacturing said product) can be extended by PTE. Moreover, the scope of protection during the period of the PTE does not extend to the full scope of the claim, but instead only to the scope of the product as approved. We anticipate applying for PTE in the United States. Similar extensions may be available in other countries where we are prosecuting patents and we likewise anticipate applying for such extensions.

Geopolitical actions in the United States and in foreign countries could increase the uncertainties and costs surrounding the prosecution or maintenance of our patent applications or those of any current or future licensors and the maintenance, enforcement or defense of our issued patents or those of any current or future licensors. For example, further to the United States and foreign government actions related to Russia’sthe invasionmilitary conflict in Ukraine and Russia may limit or prevent filing, prosecution and maintenance of Ukraine,patent theapplications Kremlinin Russia. Government actions may also prevent maintenance of issued Decreepatents 299in statingRussia. thatThese Russianactions companiescould andresult individualsin can use patented inventions without the owner’s permissionabandonment or compensation,lapse ifof theour patents or patent isapplications, heldresulting byin ownerspartial fromor “unfriendlycomplete countries,”loss which include the United States. As a result, we would not be able to enforce our otherwise validof patent rights againstin Russia. If such an infringerevent inwere Russia.to occur, it could have a material adverse effect on our business. Accordingly, our competitive position may be impaired, and our business, financial condition, results of operations and prospects may be adversely affected.

While we perform periodic searches for relevant patents and patent applications with respect to our product candidates, including canvuparatide, MBX 1416,imapextide, and MBX 4291, we cannot guarantee the completeness or thoroughness of any of our patent searches or analyses including, but not limited to, the identification of relevant patents, the scope of patent claims or the expiration of relevant patents, nor can we be certain that we have identified each and every patent and pending application in the United States and abroad that is relevant to or necessary for the commercialization of any of our product candidates in any jurisdiction. Patent applications in the United States and elsewhere are typically published approximately 18 months after the earliest filing for which priority is claimed, with such earliest filing date being commonly referred to as the priority date. Certain U.S. applications that will not be filed outside the U.S. can remain confidential until patents issue. As a result, we may be unable to identify such patents or patent applications despite our best efforts. In addition, patent applications can take many years to issue, there may be currently pending patent applications which may later result in issued patents that any of our product candidates may be accused of infringing. Generative AI resources that are publicly available also present a risk that a company may inadvertently obtain, incorporate or use a third party's intellectual property. In addition, third parties may obtain patents in the future and claim that use of our technologies infringes upon these patents. Accordingly, third parties may assert infringement claims against us based on intellectual property rights that exist now or arise in the future. The outcome of intellectual property litigation is subject to uncertainties that cannot be adequately quantified in advance. The pharmaceutical and biotechnology industries have produced a significant number of patents, and it may not always be clear to industry participants, including us, which patents cover various types of products or methods of use or manufacture. The scope of protection afforded by a patent is subject to interpretation by the courts, and the interpretation is not always uniform. If we were sued for patent infringement, we would need to demonstrate that the relevant product or methods of using the product either do not infringe the patent claims of the relevant patent or that the patent claims are invalid or unenforceable, and we may not be able to do this. Proving invalidity is difficult. For example, in the United States, proving invalidity requires a showing of clear and convincing evidence to overcome the presumption of validity enjoyed by issued patents. Even if we are successful in these proceedings, we may incur substantial costs and the time and attention of our management and scientific personnel could be diverted in pursuing these proceedings, which could significantly harm our business and operating results. In addition, parties making claims against us may be able to sustain the costs of complex patent litigation more effectively than we can because they have substantially greater resources, and we may not have sufficient resources to bring these actions to a successful conclusion.

Pursuant to SOX Section 404, we will beare required to furnish a report by our management on our internal control over financial reporting beginning with our second filing of anthis Annual Report on Form 10-K with the SEC after we become a public company.SEC. However, while we remain an emerging growth company, we will not be required to include an attestation report on internal control over financial reporting issued by our independent registered public accounting firm. To achieve compliance with SOX Section 404 within the prescribed period, we have engaged and will becontinue engagedto engage in a process to document and evaluate our internal control over financial reporting, which is both costly and challenging. In this regard, we will need to continue to dedicate internal resources, potentially engage outside consultants, adopt a detailed work plan to assess and document the adequacy of internal control over financial reporting, continue steps to improve control processes as appropriate, validate through testing that controls are functioning as documented and implement a continuous reporting and improvement process for internal control over financial reporting. Despite our efforts, there is a risk that we will not be able to conclude, within the prescribed timeframe or at all, that our internal control over financial reporting is effective as required by SOX Section 404. This could result in an adverse reaction in the financial markets due to a loss of confidence in the reliability of our financial statements.

Sales of a substantial number of shares of our common stock in the public market could occur at any time. These sales, or the perception in the market that the holders of a large number of shares of common stock intend to sell shares, could reduce the market price of our common stock. As of December 31, 2024,2025, we have 33,421,52544,927,953 shares of common stock outstanding. Of these shares, the resaleHolders of 21,513,565 shares of our outstanding common stock were restricted under securities laws or as a result of lock-up or other agreements, but are ableup to be sold after the expiration of the lock-up on March 12, 2025 and termination of restrictions under securities laws. Moreover, holders of an aggregate 20,336,599 shares of our common stock have rights, subject to conditions, to require us to file registration statements covering their shares or to include their shares in registration statements that we may file for ourselves or other stockholders. We have also registered all shares of common stock that we may issue under our equity compensation plans or that are issuable upon exercise of outstanding options. These shares can be freely sold in the public market upon issuance and once vested, subject to volume limitations applicable to affiliates and lock-up agreements. If any of these additional shares are sold, or if it is perceived that they will be sold, in the public market, the market price of our common stock could decline.

Ensuring that we have adequate internal financial and accounting controls and procedures in place so that we can produce accurate financial statements on a timely basis is a costly and time-consuming effort that needs to be re-evaluated frequently. Our internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements in accordance with generally accepted accounting principles. We have begunundertaken the process of documenting, reviewing and improving our internal controls and procedures for compliance with SOX Section 404, which will requirerequires annual management assessment of the effectiveness of our internal control over financial reporting starting with our secondthis filing of anour Annual Report on Form 10-K.

We are a clinical-stage biopharmaceutical company focused on the discoverydiscovery, development and developmentcommercialization 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 Peptide™ (the "PEP™") 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,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,hypoparathyroidism or HP.("HP"). Leveraging our proprietary PEP™ platform, we designed canvuparatide to treat the underlying pathophysiology of HP by providing a continuous, infusion-like exposure to parathyroid hormone ("PTH"),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,dose or ("peak-to-trough ratio.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. We are currently evaluating canvuparatide inIn a Phase 2 clinical trial in patients with HP. In March 2025, we announced completion of enrollment of 64 patients with HP, canvuparatide achieved the primary endpoint with a statistically significant responder rate at Week 12 and wefurther anticipatedemonstrated reportingpositive toplinesix-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 2025.2026.

Since our inception, we have devoted substantially all of our resources to drug discovery and development of our product candidates, canvuparatide, MBX 1416imapextide 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 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 $401.8$688.8 million in cumulative, aggregate gross proceeds.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 $61.9$87.0 million and $32.6$61.9 million for the years ended December 31, 20242025 and December 31, 2023,2024, respectively. We had an accumulated deficit of $137.5$224.5 million and $75.6$137.5 million as of December 31, 20242025 and December 31, 2023,2024, respectively.

advance the development of our lead product candidates, canvuparatide, MBX 1416imapextide and MBX 4291, and future product candidates;

We had cash, cash equivalents and marketable securities of $262.1$373.7 million and $80.7$262.1 million as of December 31, 20242025 and December 31, 2023,2024, 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 mid-2027.2029. 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.”

In June 2020, we entered into an Exclusive License Agreement with Indiana University Research and Technology Corporation,Corporation or IURTC,("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. MBXCanvuparatide, 2109, MBX 1416imapextide, 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.

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 totaltotaled 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.

Other income (expense)

Direct research and development program expenses related to canvuparatide increased by $11.7$15.6 million,million primarily due to increased activities related to conduct of the ongoing 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 associatedrelated withto conductingIND-enabling preclinical studies. Direct program expenses related to MBXimapextide 1416 increaseddecreased by $1.4$7.4 million, primarily due to the timing of costs associated with conducting preclinical studies and an increase in costs associated with conductcompletion 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 $9.9$4.7 million primarily due to pipeline candidate development activities, specifically including IND-enabling preclinical studies related to MBX 4291.activities. Personnel-related costs (including stock-based compensation), increased by $4.6$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 $1.3$0.7 million.

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, as compared to $6.8 million for the year ended December 31, 2023.2024. The increase of $4.0$8.1 million was primarily due to higher professional fees related to legallegal, accounting and accountingconsulting 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, 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, as compared to $2.7 million for the year ended December 31, 2023.2024. The increase of $3.5$4.8 million was due to increased interest on our cash, cash equivalents and marketable securities, which increased primarily due to our IPO inthe September 20242025 and the Series C Convertible Preferred Stock financing in August 2024.Offering.

Since our inception, we have incurred significant operating losses. We have historically funded our operations primarily through our IPOIPO, 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 $401.8$688.8 million in cumulative, aggregate gross proceeds.proceeds to date. As of December 31, 20242025 and December 31, 2023,2024, we had $262.1$373.7 million and $80.7$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.

We had $262.1$373.7 million and $80.7$262.1 million in cash, cash equivalents and marketable securities as of December 31, 20242025 and December 31, 2023,2024, 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 mid-2027.2029. 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.

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, 20242025 and 2023,2024, respectively. A portion of our stock option program allowsallowed 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, 2024,2025, the unrecognized stock-based compensation expense related to stock options was $17.9$25.2 million and is expected to be recognized as expense over a weighted-average period of approximately 3.12.7 years. The intrinsic value of all outstanding stock options as of December 31, 20242025 was approximately $34.3$97.8 million, based on the closing NASDAQ stock price of $18.43$31.54 per share as of December 31, 2024.2025.

Since our inception, we have devoted substantially all of our resources to drug discovery and development of our product candidates, canvuparatide, imapextide andimapextide, MBX 4291,4291 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 sold 2,250,986 shares of our common stock under our Open Market Sale AgreementSM with Jefferies, LLC (the "February 2026 ATM Offering"), which generated approximately $87.1 million in aggregate gross proceeds. 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. In March 2026, we filed an automatic shelf registration statement with the Securities and Exchange Commission (File No. 333-294237) and increased the amount available under the Open Market Sales AgreementSM with Jefferies, LLC (the "March 2026 Sales Agreement"), under which we may now, from time to time in one or more offerings, sell and issue shares of our common stock having an aggregate price of up to $250.0 million.

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 $23.5$60.6 million and $23.9$43.3 million for the threesix months ended MarchJune 31,30, 2026 and 2025, respectively. We had an accumulated deficit of $248.0$285.1 million and $224.5 million as of MarchJune 31,30, 2026 and December 31, 2025, respectively.

advance the development of our lead product candidates, canvuparatide, imapextideMBX 4291, MBX 5765 and MBX 4291,6180, and future product candidates;

We had cash, cash equivalents and marketable securities of $440.0$418.6 million and $373.7 million as of MarchJune 31,30, 2026 and December 31, 2025, respectively. We believe 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” from Item 1A Risk Factors in our Annual Report.

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 (MBX 2109), imapextide (MBX 1416), MBX 4291, MBX 5765 and MBX 42916180 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.

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 total 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. In the threefirst monthsquarter ended March 31,of 2026, we triggered a $0.1 million milestone payment to IURTC following the completion of the end of Phase 2 meeting with the FDA related to the Phase 2 clinical trial of canvuparatide, which was included in accrued expenses in the condensed balance sheet as of March 31, 2026 and was paid in the second quarter of 2026. As of MarchJune 31,30, 2026, future remaining clinical and regulatory milestone payments in the IURTC License Agreement and all amendments totaled up to $8.2 million.

Comparison of the three months ended MarchJune 31,30, 2026 and 2025

The following table summarizes our results of operations for the three months ended MarchJune 31,30, 2026 and 2025 (in thousands):

Research and development expenses were $18.5$31.0 million for the three months ended MarchJune 31,30, 2026, as compared to $22.4$17.7 million for the three months ended MarchJune 31,30, 2025. The decreaseincrease of $3.9$13.3 million consisted of the following:

Direct research and development program expenses related to canvuparatide decreasedincreased by $0.2$5.0 million, primarily due to substantiallyclinical allstart-up activity related to the conduct of the Phase 2 clinical trial being completed in 2025, offset by increased manufacturing in preparation for the Phase 3 clinical trial, clinical supply manufacturing to support the Phase 3 clinical trial and the ongoing Phase 2 open-label extension clinical trial. Direct program expenses for MBX 4291 decreasedincreased by $3.8$4.5 million primarily due to the timing of preclinical studies and manufacturing activities, partially offset by the ongoing conduct of the Phase 1 clinical trial of MBX 4291. Direct program expenses related to imapextide decreased by $0.9 million, primarily due to the timing of preclinical studies as compared to the first quarter of 2025.trial. Direct program expenses for imapextide and preclinical and other programs increasedremained byrelatively $0.1 million primarily due to pipeline candidate development activities.unchanged. Personnel-related costs (including stock-based compensation), increased by $1.8$3.4 million, primarily due to increased headcount and stock-based compensation expense. Facility-related and other expenses, which include allocated overhead, including rent, repairs and maintenance costs, common facilities and information technology-related expenses allocated to research and development decreasedincreased by $0.8$0.4 million.

General and administrative expenses were $8.8$9.9 million for the three months ended MarchJune 31,30, 2026, as compared to $4.1 million for the three months ended MarchJune 31,30, 2025. The increase of $4.7$5.9 million was primarily due to higher personnel-related costs (including stock-based compensation) resulting from continued expansion of both our executive leadership team and general infrastructure to support growth in our operations and separation related costs.operations.

Interest and other income, net, which includes interest income and amortization of premiums and discounts on our investments in marketable securities, were $3.7$3.8 million for the three months ended MarchJune 31,30, 2026, as compared to $2.6$2.4 million for the three months ended MarchJune 31,30, 2025. The increase of $1.1$1.4 million was due to increased interest on our cash, cash equivalents and marketable securities, which increased primarily due to the September 2025 Offering and the February 2026 ATM Offering.

Since our inception, we have incurred significant operating losses. We have historically funded our operations primarily through our IPO, the September 2025 Offering, the February 2026 ATM Offering, and sales of our convertible preferred stock and convertible notes, which have generated approximately $688.8 million in cumulative, aggregate gross proceeds. As of MarchJune 31,30, 2026 and December 31, 2025, we had $440.0$418.6 million and $262.1$373.7 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.

We had $440.0$418.6 million and $262.1$373.7 million in cash, cash equivalents and marketable securities as of MarchJune 31,30, 2026 and December 31, 2025, 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 unaudited condensed 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.

Net cash used in operating activities for the threesix months ended MarchJune 31,30, 2026 was $20.2$42.8 million. This was primarily due to our net loss of $23.5$60.6 million, partially offset by non-cash charges of $5.0$10.8 million. Non-cash charges primarily consisted of $5.5$11.5 million of stock-based compensation expense andexpense, $0.1 million of depreciation expense related to our property and equipment,equipment and $0.1 million of amortization expense related to our right-of-use assets, partially offset by $0.6$1.0 million of net amortization and accretion of marketable securities. The changes in our net operating assets and liabilities primarily consisted of a $0.9$7.1 million increase in accounts payable and accrued expenses primarily related to balances with CROs and CDMOs andCDMOs, a $0.7$0.5 million increasedecrease in our prepaid expenses and other current assets related to prepaid balances with CROs and CDMOs.CDMOs, and a net increase of $0.3 million related to our operating lease liabilities.

Net cash used in operating activities for the threesix months ended MarchJune 31,30, 2025 was $22.7$40.1 million. This was primarily due to our net loss of $23.9$43.3 million, partially offset by net cash provided by changes in our operating assets and liabilities of $0.6$1.6 million and non-cash charges of $0.6$1.7 million. The changes in our net operating assets and liabilities primarily consisted of a $1.6$0.9 million decreaseincrease in our prepaid expenses and other current assets related to prepaid balances with CROs, partially offset by a $1.0$0.8 million decreaseincrease in accounts payable and accrued expenses primarily related to balances with CDMOs.CROs. Non-cash charges primarily consisted of $1.8$3.8 million of stock-based compensation expense, $0.1 million of depreciation expense related to our property and equipment and $0.1 million of depreciationamortization expense,expense related to our right-of-use asset, partially offset by $1.3$2.3 million of net amortization and accretion of marketable securities.

Net cash used in investing activities for the threesix months ended MarchJune 31,30, 2026 was $97.1$67.9 million, which consisted of purchases of marketable securities of $154.2$208.0 million and purchases of property and equipment of $0.4$1.3 million, partially offset by maturities of marketable securities of $57.5$141.5 million.

Net cash provided by investing activities for the threesix months ended MarchJune 31,30, 2025 was $3.2$29.2 million, which consisted of maturities of marketable securities of $57.2$130.3 million and redemptions of marketable securities of $5.0$6.0 million, partially offset by purchases of marketable securities of $58.9$106.3 million and purchases of property and equipment of $0.8 million.

Net cash provided by financing activities for the threesix months ended MarchJune 31,30, 2026 was $87.4$89.8 million, which consisted of proceeds of $85.4 million from the February 2026 ATM Offering, net of underwriting discounts and commissionscommissions, and $2.4$4.6 million of proceeds from the exercise of common stock options, and $0.3 million of proceeds from the purchase of shares of our common stock pursuant to the 2026 ESPP, partially offset by payments totaling $0.4$0.5 million related to offering costs for the February 2026 ATM Offering.

Net cash provided by financing activities for the threesix months ended MarchJune 31,30, 2025 was immaterial.$1.3 million, which consisted of proceeds from the exercise of common stock options.

We have entered into two separate lease agreements for corporate office space and laboratory space, with terms extending through December 2028 and December 2025, respectively. The lease for our corporate office space was amended in May 2025 as further discussed in Note 9 to our interim unaudited condensed financial statements included elsewhere in this Quarterly Report. As of March 31, 2026, our future remaining operating lease payments were $0.7 million, with $0.2 million payable within the next twelve months, with respect to leases already commenced as of such date. As of December 31, 2025, our future remaining operating lease payments were $0.7 million, with $0.2 million payable within the next twelve months, with respect to leases already commenced as of such date.

InAdditionally, on February 24, 2026, the Companywe entered into aan operating lease agreement with 5 Burlington Woods, LLC to lease new office and laboratory space in Burlington, Massachusetts.Massachusetts ("Burlington Lease"). The lease agreementcommenced provideseffective anApril estimated lease commencement date of May 1,14, 2026, with the rent commencing five months from the lease commencement date.date, which will be September 14, 2026 ("rent commencement date"). The lease term will beis four years from the rent commencement date, with a one-time option to extend the lease term for a period of three years. The option to extend was not considered reasonably certain as of the lease inception. The aggregate base rent over the four-year lease term is approximately $3.4 million.million TheAs Companyof isJune evaluating30, 2026, our future remaining operating lease payments were $4.0 million, with $0.9 million payable within the newnext twelve months, with respect to leases already commenced as of such date. As of December 31, 2025, our future remaining operating lease termspayments pursuantwere $0.7 million, with $0.2 million payable within the next twelve months, with respect to ASCleases 842already andcommenced isas stillof assessingsuch the financial statement impact.date.

During the threesix months ended MarchJune 31,30, 2026, there were no material changes to our critical accounting policies and estimates described under Management’s Discussion and Analysis of Critical Accounting Policies and Estimates which are included in our 2025 Annual Report.

We currently qualify as an “emerging growth company,” as defined in 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 Quarterly 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.