ASSEMBLY BIOSCIENCES, INC.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

For the quarterly period ended March 31,2026

OR

For the transition period from to.

Commission file number:001-35005

(Exact name of Registrant as specified in its charter)

(833)509-4583

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes☐No☒

As of May 1, 2026, there were 15,892,608 shares of the registrant’s common stock outstanding.

Index

References to Assembly Biosciences, Inc.

Throughout this Quarterly Report on Form 10-Q, the “Company,” “Assembly,” “we,” “us,” and “our,” except where the context requires otherwise, refer to Assembly Biosciences, Inc. and its consolidated subsidiaries, and “board of directors” refers to the board of directors of Assembly Biosciences, Inc.

Forward-Looking Statements

This Quarterly Report on Form 10-Q contains “forward-looking statements” that are subject to certain risks and uncertainties, including, without limitation, those set forth in Part I, Item 1A of our Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission (SEC) on March 19, 2026 (2025 Annual Report) and Part II, Item 1A of this Quarterly Report on Form 10-Q under the heading “Risk Factors,” that could cause actual results to materially differ. Such risks and uncertainties include, among other things:

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our ability to realize the potential benefits of our collaboration with Gilead Sciences, Inc. (Gilead), including all financial aspects of the collaboration and equity investments;

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our ability to initiate and complete clinical studies involving our therapeutic product candidates, including studies contemplated by our collaboration with Gilead, in the currently anticipated timeframes or at all;

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safety and efficacy data from clinical or nonclinical studies may not warrant further development of our product candidates;

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clinical and nonclinical data may not differentiate our product candidates from other companies’ candidates;

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our ability to maintain financial resources and secure additional funding necessary to continue our research activities, clinical studies and other business operations;

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potential effects of changes in government regulation; and

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results of nonclinical studies may not be representative of disease behavior in a clinical setting and may not be predictive of the outcomes of clinical studies.

You are urged to consider statements that include the words may, will, would, could, should, might, believes, hopes, estimates, projects, potential, enable, expects, plans, anticipates, intends, continues, forecast, designed, goal or the negative of those words or other comparable words to be uncertain and forward-looking. In particular, forward-looking statements include, but are not limited to, statements regarding the timing of commencement of future clinical studies involving our therapeutic product candidates or therapeutic product candidates that Gilead has licensed from us; and our ability to successfully complete, and receive favorable results in, clinical studies for our product candidates. We intend such forward-looking statements to be covered by the safe harbor provisions contained in Section 27A of the Securities Act of 1933, as amended (the Securities Act), and Section 21E of the Securities Exchange Act of 1934, as amended (the Exchange Act). Except as required by law, we assume no obligation to update publicly any forward-looking statements, whether as a result of new information, future events or otherwise.

Risk Factors Summary

The following is a summary of the principal risks that could adversely affect our business, operations and financial results. For more information, see Part II, Item 1A in this Quarterly Report on Form 10-Q for the period ended March 31, 2026.

Risks Related to Our Business

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We have no approved products and depend on the future success of the product candidates in our research and development pipeline.

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We are not currently profitable and might never become profitable, and we will need additional financing to complete the development of any product candidates and fund our activities into the future.

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We expect our collaboration with Gilead to be a critical part of the development, manufacture and commercialization of our product candidates.

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Nonclinical and clinical studies required for our product candidates are expensive and time-consuming and may fail to demonstrate the level of safety and efficacy necessary for product approval.

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We rely on contract resource organizations (CROs) to conduct some of our nonclinical and clinical studies due to our lack of suitable facilities and resources. In addition, parts of our business are reliant on CROs, vendors, suppliers and other service providers in locations outside of the United States, including China.

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Top-line, preliminary or interim data may not accurately reflect the final results of a particular study.

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We rely on third parties to formulate and manufacture our product candidates and products that we study in combination with our product candidates. Our use of third parties may increase the risk that we will not have sufficient quantities of our product candidates or other products on time or at an acceptable cost.

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If we lose key management personnel and cannot recruit and retain similarly qualified replacements, our business may materially suffer.

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Our collaboration partners might delay, prevent or undermine the success of our product candidates.

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We may not be successful in establishing and maintaining collaborations, which could adversely affect our ability to develop certain of our product candidates.

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We rely on data provided by third parties that has not been independently verified.

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Research, development and commercialization goals, including data releases, may not be achieved in the timeframes that we publicly estimate, which could have an adverse impact on our business and could cause our stock price to decline.

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Competitors' developments may render our product candidates or technologies obsolete or non-competitive.

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Other companies with products using the same or similar mechanisms of action as ours may produce negative clinical data, which would adversely affect public and clinical communities’ perceptions of our product candidates, and may negatively impact regulatory approval of, or demand for, our potential products.

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Significant disruptions of information technology systems or breaches of data security, including cybersecurity incidents, could materially and adversely affect our business.

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Our ability to use our net operating loss and credit carryforwards and certain other tax attributes may be limited.

Risks Related to Our Regulatory and Legal Environment

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We are and will be subject to extensive and costly government regulation, and the failure to comply with these regulations may have a material adverse effect on our operations and business.

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The regulatory approval processes of the FDA and comparable foreign authorities are lengthy, time consuming and inherently unpredictable.

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We and our third-party partners and service providers are subject to stringent privacy laws, information security laws, regulations, policies and contractual obligations related to data privacy and security, and compliance with such laws, regulations, policies and contractual obligations could result in additional costs and liabilities to us and failure to comply could adversely affect our business.

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We and our collaborators may be subject, directly or indirectly, to applicable U.S. federal and state anti-kickback, false claims laws, physician payment transparency laws, other fraud and abuse laws or similar healthcare and security laws and regulations, and health information privacy and security laws, which could expose us or them to criminal sanctions, civil penalties, exclusion or suspension from federal and state healthcare programs, contractual damages, reputational harm and diminished profits and future earnings.

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We face the risk of product liability claims and might not be able to obtain insurance.

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We might be exposed to liability claims associated with the use of hazardous materials and chemicals.

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Our employees, independent contractors, consultants, collaborators and CROs may engage in misconduct or other improper activities, including noncompliance with regulatory standards and requirements for which we may be held responsible and which could result in significant liability for us and harm our reputation.

Risks Related to Our Intellectual Property

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Our business depends on protecting our intellectual property.

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We may incur substantial costs as a result of litigation or other proceedings relating to our patents and other intellectual property rights.

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We may infringe the intellectual property rights of others, which may prevent or delay our product development efforts and stop us from commercializing or increase the costs of commercializing our product candidates.

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The cost of maintaining our patent protection globally is high and requires continuous review and compliance.

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Intellectual property rights do not address all potential threats to any competitive advantage we may have.

Risks Related to Our Common Stock

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The price of our common stock has in the past and may continue to fluctuate significantly.

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Our bylaws provide that the Court of Chancery of the State of Delaware will be the sole and exclusive forum for certain types of actions and proceedings that may be initiated by our stockholders, which could limit our stockholders’ ability to bring a claim in a judicial forum they find favorable.