DYN US Equity☆

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

The following discussion and analysis of our financial condition and results of operations should be read in conjunction with our consolidated financial statements and related notes appearing at the end of this Annual Report on Form 10-K. Some of the information contained in this discussion and analysis or set forth elsewhere in this Annual Report on Form 10-K, including information with respect to our plans and strategy for our business, includes forward-looking statements that involve risks and uncertainties. As a result of many factors, including those factors set forth in the “Risk Factors” section of this Annual Report on Form 10-K, our actual results could differ materially from the results described in, or implied by, the forward-looking statements contained in the following discussion and analysis.

Overview

We are a clinical-stage company focused on delivering functional improvement for people living with genetically driven neuromuscular diseases. Our proprietary FORCE platform is designed to leverage the transferrin receptor 1, or TfR1, to deliver targeted therapeutics to muscle tissue and the central nervous system, or CNS. The FORCE platform utilizes an antigen-binding fragment antibody, or Fab, targeting TfR1 conjugated to a payload that we rationally design to target the genetic basis of the disease we are seeking to treat. With our FORCE platform, we have the flexibility to deploy different classes of payloads (such as oligonucleotides and enzymes) with specific mechanisms of action that modify target functions. We currently leverage this modularity to focus on neuromuscular diseases with high unmet need, with etiologic targets and with clear translational potential from preclinical disease models to well-defined clinical development and regulatory pathways.

Using our FORCE platform, we are assembling a broad portfolio of product candidates, including product candidates being developed for Duchenne muscular dystrophy, or DMD, myotonic dystrophy type 1, or DM1, facioscapulohumeral dystrophy, or FSHD, and Pompe disease. In addition, we plan to expand our portfolio through development efforts focused on diseases involving the CNS, rare skeletal muscle diseases, and cardiac and metabolic muscle diseases, including some with larger patient populations. We have identified product candidates for each of our DMD, DM1, FSHD and Pompe programs that are in varying stages of preclinical and clinical development.

DMD

We are developing zeleciment rostudirsen, or z-rostudirsen (also known as DYNE-251), for the treatment of exon 51 skip amenable DMD. Z-rostudirsen is designed to enable the production of near full-length dystrophin in muscle and the CNS to provide functional improvement. Z-rostudirsen has received Breakthrough Therapy, Fast Track and Rare Pediatric Disease designations from the U.S. Food and Drug Administration, or FDA, as well as Orphan Drug designation from the FDA, the European Medicines Agency and the Japanese Ministry of Health, Labour and Welfare for the treatment of individuals with DMD, amenable to exon 51 skipping. Additionally, we are advancing four development candidates (DYNE-253, DYNE-245, DYNE-244 and DYNE-255) for the treatment of DMD amenable to skipping of exons 53, 45, 44, 55, respectively, into IND-enabling studies.

Z-rostudirsen is currently being evaluated in the DELIVER trial, a global Phase 1/2 clinical trial which is designed to be registrational. We plan to submit a biologics license application, or BLA, to the FDA for U.S. Accelerated Approval in the second quarter of 2026 based on dystrophin as a surrogate endpoint. We continue to expect a potential U.S. launch of z-rostudirsen in the first quarter of 2027, assuming FDA grants priority review and FDA approval is received on the anticipated timeline. Further, we plan to initiate a global confirmatory Phase 3 clinical trial of z-rostudirsen in the second quarter of 2026, and we have aligned with the FDA on the Phase 3 trial design and protocol. We continue to pursue approval pathways outside of the United States for z-rostudirsen.

DM1

We are developing zeleciment basivarsen, or z-basivarsen (also known as DYNE-101), for the treatment of DM1. Z-basivarsen is designed to deliver functional improvement in individuals living with DM1 by

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reducing toxic nuclear DMPK RNA to release splicing proteins and allow normal mRNA processing. Z-basivarsen has been granted Breakthrough Therapy, Orphan Drug and Fast Track designations by the FDA and Orphan Drug designation by the European Medicines Agency and the Japanese Ministry of Health, Labour and Welfare for the treatment of DM1.

Z-basivarsen is being evaluated in the ACHIEVE trial, a global Phase 1/2 clinical trial which is designed to be registrational. We anticipate a potential U.S. launch of z-basivarsen in the first quarter of 2028, assuming we receive favorable data, priority review is granted, and FDA approval is received on the anticipated timeline. We plan to initiate a Phase 3 clinical trial of z-basivarsen in March 2026, and we have aligned with the FDA on the Phase 3 trial design and protocol. We continue to pursue approval pathways outside of the United States for z-basivarsen.

FSHD

We are developing DYNE-302 for the treatment of FSHD. DYNE-302 is designed to deliver functional improvement in individuals living with FSHD by reducing aberrant DUX4 expression. We are progressing DYNE-302 toward clinical development.

In June 2024 and June 2025, we announced preclinical data for DYNE-302, our product candidate for FSHD, that demonstrated robust and durable DUX4 suppression and functional benefit in a mouse model. We generated these data using an innovative hTfR1/iFLExD mouse model we developed that expresses TfR1 and enables tunable DUX4 induction in skeletal muscle. In hTfR1/iFLExD mice, a single intravenous dose of DYNE-302 resulted in dose-dependent and robust reduction of the DUX4 transcriptome that lasted up to three months, with benefit on muscle structure. DYNE-302 also demonstrated prevention as well as reversal of muscle weakness.

Pompe

We are developing a product candidate, DYNE-401, to deliver an enzyme replacement therapy to address the deficiency of the lysosomal enzyme, GAA, that causes Pompe disease. We engineered FORCE-GAA by leveraging the FORCE platform and evaluated efficacy in vivo using hTfR1/6Neo mice, that were developed by crossing the well-established 6Neo mouse model of Pompe with mice expressing human transferrin receptor 1. Using this approach, intravenous administration cleared glycogen in muscle and the CNS and normalized lysosomal size in hTfR1/6Neo mice. This approach reduced serum neurofilament light chain, a biomarker of axonal injury, providing evidence of benefit in the CNS and displayed superior dose potency compared to GAA alone. Additional data with this approach supported the potential for monthly dosing which is less frequent than approved enzyme replacement therapies for Pompe.

We were incorporated and commenced operations in 2017. Since our incorporation, we have devoted substantially all of our financial resources and efforts to organizing and staffing our company, business planning, raising capital, conducting research and development activities and filing and prosecuting patent applications. We do not have any products for sale and have not generated any revenue from product sales or otherwise. To date, we have principally raised capital through sales of equity securities and our borrowing under our Loan and Security Agreement, or the Loan Agreement, with Hercules Capital, Inc., or Hercules.

Since our inception, we have incurred significant operating losses. Our ability to generate any product revenue or product revenue sufficient to achieve profitability will depend on the successful development and eventual commercialization of one or more product candidates. For the years ended December 31, 2025, 2024 and 2023, we reported net losses of $446.2 million, $317.4 million and $235.9 million, respectively. As of December 31, 2025, we had an accumulated deficit of $1.4 billion.

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We expect to continue to incur significant expenses and increasing operating losses for the foreseeable future. We expect that our expenses and capital expenditure requirements will increase substantially in connection with our ongoing activities, particularly if and as we:

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advance our product candidates for DMD, DM1, FSHD and Pompe and conduct research programs in additional indications;

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expand the capabilities of our proprietary FORCE platform;

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seek marketing approvals for any product candidates that successfully complete clinical trials;

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obtain, expand, maintain, defend and enforce our intellectual property portfolio;

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hire additional clinical, regulatory and scientific personnel;

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establish manufacturing sources for any product candidate we may develop, including the Fab antibody, linkers and therapeutic payload that will comprise the product candidate, and secure supply chain capacity to provide sufficient quantities for preclinical and clinical development and commercial supply;

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ultimately establish a sales, marketing and distribution infrastructure to commercialize any products for which we may obtain marketing approval; and

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add operational, legal, compliance, financial and management information systems and personnel to support our research, product development and future commercialization efforts, as well as to support our operations as a public company.

We will not generate revenue from product sales unless and until we successfully complete clinical development and obtain regulatory approval for any product candidates we may develop. If we obtain regulatory approval for or otherwise commercialize any product candidates we may develop, we expect to incur significant expenses related to developing our commercialization capabilities to support product sales, marketing and distribution. Further, we expect to continue to incur additional costs associated with operating as a public company.

As a result, we will need substantial additional funding to support our continuing operations and pursue our growth strategy. Until such time as we can generate significant revenue from product sales, if ever, we expect to finance our operations through a combination of equity offerings, debt financings, collaborations, strategic alliances and licensing arrangements, and terms loans under our Loan Agreement with Hercules. We may be unable to raise additional funds or enter into such other agreements or arrangements when needed, on favorable terms, or at all. If we fail to raise capital or enter into such agreements or arrangements as and when needed, we may have to significantly delay, reduce or eliminate the development or future commercialization of one or more product candidates we may develop.

Because of the numerous risks and uncertainties associated with product development, we are unable to accurately predict the timing or amount of increased expenses or when, or if, we will be able to achieve profitability. Even if we do achieve profitability, we may not be able to sustain or increase profitability on a quarterly or annual basis. If we fail to become profitable or are unable to sustain profitability on a continuing basis, then we may be unable to raise capital, maintain our research and development efforts, expand our business or continue our operations at planned levels, and as a result we may be forced to substantially reduce or terminate our operations.

We believe that our existing cash, cash equivalents and marketable securities will enable us to fund our operating expenses, debt service obligations and capital expenditure requirements into the first quarter of 2028.

We have based our estimate as to how long we expect we will be able to fund our operations, debt service obligations and capital expenditure requirements on assumptions that may prove to be wrong. We could use our available capital resources sooner than we currently expect, in which case we would be

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required to obtain additional financing, which may not be available to us on acceptable terms, or at all. Our failure to raise capital as and when needed would have a negative impact on our financial condition and our ability to pursue our business strategy. See “—Liquidity and capital resources” below. These estimates do not give effect to any additional funding tranches we may obtain access to under our Loan Agreement with Hercules, subject to the achievement of specified clinical, regulatory and commercial milestones, and do not give effect to any revenue we may generate on commercial sales of any products for which we obtain regulatory approval.

Impact of Tariffs

The U.S. administration has announced or imposed a series of tariffs on U.S. trading partners. In response, several countries have threatened or imposed retaliatory measures. While we have not experienced, and do not currently expect to experience, any significant direct impact from these tariffs and retaliatory measures, we could experience a negative impact on our costs of materials and production processes and supply chain disruptions. Supply chain disruptions may impact the development, testing and clinical trials of our product candidates, and regulatory approval or commercial launch of any resulting product may be delayed or not obtained, which could significantly harm our business. The full extent of the future impact of these and other threatened measures remains uncertain. We continue to monitor these tariffs and retaliatory measures and their possible effects on our business.

Components of our results of operations

Revenue

We have not generated any revenue since our inception and do not expect to generate any revenue from the sale of products until at least 2027, if at all. If our development efforts are successful and we commercialize products, or if we enter into collaboration or license agreements with third parties, we may generate revenue in the future from product sales, as well as upfront, milestone and royalty payments from such collaboration or license agreements, or a combination thereof.

Research and development expenses

Research and development expenses consist primarily of costs incurred for our research activities and development of our product candidates. These expenses include:

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development and operation of our proprietary FORCE platform;

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employee-related expenses, including salaries, related benefits and stock-based compensation expense, for employees engaged in research and development functions;

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expenses incurred in connection with our research programs and development of our product candidates, including those incurred under agreements with third parties, such as consultants and contract research organizations, or CROs, to conduct preclinical studies and clinical trials;

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the cost of laboratory supplies and acquiring, developing and manufacturing materials for use in our research, preclinical studies and clinical trials, including those incurred under agreements with third parties, such as consultants and contract manufacturing organizations, or CMOs;

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facilities, depreciation and other expenses, which include direct or allocated expenses for rent and maintenance of facilities and insurance; and

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costs related to compliance with regulatory requirements.

We expense research and development costs as incurred. Advance payments that we make for goods or services to be received in the future for use in research and development activities are recorded as prepaid expenses. The prepaid amounts are expensed as the related goods are delivered or the services are performed.

Our direct external research and development expenses consist of costs that include fees, reimbursed materials and other costs paid to consultants, contractors, CMOs and CROs in connection with our

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development, manufacturing and clinical activities. We have not allocated our direct external research and development costs to specific programs or product candidates that are not in clinical development.

Product candidates in later stages of clinical development generally have higher development costs than those in earlier stages of clinical development, primarily due to the increased size and duration of later-stage clinical trials. Accordingly, we expect that our research and development expenses will increase substantially as we advance z-rostudirsen and z-basivarsen through clinical trials, in connection with our preclinical and clinical development activities of DYNE-302, our FSHD product candidate, and DYNE-401, our Pompe disease product candidate, and if and as we advance any other product candidates through preclinical studies and clinical trials. At this time, we cannot accurately estimate or know the nature, timing and costs of the efforts that will be necessary to complete the preclinical and clinical development of any product candidates we may develop. The successful development of any product candidate is highly uncertain. This is due to the numerous risks and uncertainties associated with product development, including the following:

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the timing and progress of preclinical and clinical development activities;

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the number and scope of programs we decide to pursue and their regulatory paths to market;

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the need to raise funding to complete preclinical and clinical development of any product candidates we may develop;

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our ability to establish new licensing or collaboration arrangements and the progress of the development efforts of third parties with whom we may enter into such arrangements;

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our ability to maintain our current research and development programs and to establish new programs;

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the successful initiation, enrollment and completion of clinical trials with safety, tolerability and efficacy profiles that are satisfactory to the FDA or any comparable foreign regulatory authority;

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the receipt and related terms of regulatory approvals from applicable regulatory authorities for any product candidates we may develop;

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the availability of specialty raw materials for use in production of any product candidate we may develop;

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establishing agreements with third-party manufacturers for supply of product candidate components for our clinical trials;

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our ability to obtain and maintain patents, trade secret protection and regulatory exclusivity, both in the United States and internationally;

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our ability to protect our other rights in our intellectual property portfolio;

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commercializing product candidates, if and when approved, whether alone or in collaboration with others; and

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obtaining and maintaining third-party insurance coverage and adequate reimbursement for any approved products.

A change in the outcome of any of these variables with respect to the development of any product candidate we may develop could significantly change the costs and timing associated with the development of that product candidate. We may never succeed in obtaining regulatory approval for any product candidate we may develop.

General and administrative expenses

General and administrative expenses consist primarily of employee-related expenses, including salaries, related benefits and stock-based compensation for employees in executive, finance, corporate and business development, commercial and administrative functions. General and administrative expenses also include legal fees relating to patent and corporate matters; professional fees for accounting, auditing, tax and administrative consulting services; insurance costs; administrative travel expenses; commercial

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readiness activities; and facility-related expenses, which include allocated expenses for rent, depreciation and maintenance of facilities and other operating costs.

We anticipate that our general and administrative expenses will increase in the future as we increase our headcount to support our growth strategy. In addition, if we obtain regulatory approval for a product candidate and do not enter into a third-party commercialization collaboration, we expect to incur significant expenses related to building a sales and marketing team to support product sales, marketing and distribution activities.

Interest income

Interest income consists of interest earned on our cash, cash equivalents and marketable securities.

Interest expense

Interest expense consists of amortization of debt issuance costs and discount and interest expense under the Loan Agreement with Hercules.

Other income (expense), net

Other income (expense), net consists of realized gains and losses on sales of marketable securities and foreign currency gains and losses.

Income taxes

Since our inception, we have not recorded any U.S. federal or state income tax benefits for the net losses we have incurred in any year or for our earned research and development tax credits, due to our uncertainty of realizing a benefit from those items. As of December 31, 2025, we had federal and state net operating loss carryforwards of $981.6 million and $1.0 billion, respectively. The federal net operating loss carryforwards are indefinite lived and the state net operating loss carryforwards begin to expire in 2038. As of December 31, 2025, we also had federal and state research and development tax credit carryforwards of $49.0 million and $6.2 million which begin to expire in 2039 and 2033, respectively.

Results of operations

Comparison of the years ended December 31, 2025 and 2024

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

Year Ended December 31,

Operating expenses:

Other (expense) income:

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Research and development expenses

The following table summarizes our research and development expenses for the years ended December 31, 2025 and 2024:

Year Ended December 31,

Direct research and development expenses by product candidate:

Unallocated research and development expenses:

Expenses related to z-rostudirsen increased in the year ended December 31, 2025 compared to the year ended December 31, 2024. This was attributable to an increase in clinical trial activity for the DELIVER trial's registrational expansion cohort and Phase 3 start-up costs in advance of anticipated commencement in the second quarter of 2026, as well as increased analytical work to support planned regulatory activities, including preparations for a BLA submission in the second quarter of 2026. Expenses related to z-basivarsen increased in the year ended December 31, 2025 compared to the year ended December 31, 2024. This was attributable to higher manufacturing activity in 2025 related to process performance qualification batches to support a potential future BLA filing for U.S. accelerated approval, higher manufacturing activity to ensure a sufficient clinical supply of drug product for the ongoing ACHIEVE trial and an increase in clinical trial activity for the ACHIEVE trial's registrational expansion cohort and Phase 3 start-up costs in advance of anticipated commencement in the first quarter of 2026.

The increase in platform and external research and development expenses in the year ended December 31, 2025 was primarily due to increased external research activity associated with our preclinical programs and product candidates, primarily DYNE-302 and DYNE-401. The increase in personnel-related expenses was primarily due to increased headcount in our research and development function of 37 employees and higher stock-based compensation expense for awards granted to new hires and existing employees, as well as the acceleration of vesting terms and modification of previously granted awards in connection with entering into separation and consulting agreements with our former chief medical officer in the year ended December 31, 2025. The increase in facility-related and other expenses was primarily due to the increased costs of supporting a larger number of research and development personnel.

General and administrative expenses

The following table summarizes our general and administrative expenses for the years ended December 31, 2025 and 2024:

Year Ended December 31,

The increase in personnel-related expenses in the year ended December 31, 2025 compared to the year ended December 31, 2024 was due to increased headcount in our general and administrative function of

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30 employees in the year ended December 31, 2025. The decrease in stock-based compensation expense in the year ended December 31, 2025 was primarily the result of acceleration of vesting terms and modification of previously granted awards in connection with entering into separation and consulting agreements with our former chief executive officer, former chief business officer and former chief operating officer in the year ended December 31, 2024. Professional and consulting fees increased in the year ended December 31, 2025 due to the higher consulting costs for commercial preparation activities and to support the overall growth of the organization in 2025. Facility-related and other expenses increased due to the increased costs of supporting a larger number of general and administrative personnel.

Interest income

Interest income for the years ended December 31, 2025 and 2024 was $29.9 million and $26.9 million, respectively, due to interest earned on invested cash balances. The increase in interest income was due to increased cash, cash equivalents and marketable securities balances in the year ended December 31, 2025.

Interest expense

Interest expense for the year ended December 31, 2025 was $6.2 million due to our entry into the Loan Agreement with Hercules in June 2025 and related amendment in December 2025. No interest expense was incurred in the year ended December 31, 2024.

Other expense, net

Other expense for the year ended December 31, 2025 was $1.7 million primarily due to foreign currency gains and losses. Other expense for the year ended December 31, 2024 was $0.5 million primarily due to foreign currency gains and losses.

Comparison of the years ended December 31, 2024 and 2023

Discussion and analysis of the results of operations for the year ended December 31, 2024 as compared to the results of operations for the year ended December 31, 2023 is included under the heading “Item 7.Management’s Discussion and Analysis of Financial Condition and Results of Operations” in our Annual Report on Form 10-K for the year ended December 31, 2024, as filed with the SEC on February 27, 2025.

Liquidity and capital resources

Sources of liquidity

Since our inception, we have incurred significant operating losses. We expect to incur significant expenses and operating losses for the foreseeable future as we support our continued research activities and development of our product candidates and platform. We have not yet commercialized any product candidates, and we do not expect to generate revenue from sales of any product candidates until at least 2027, if at all. To date, we have funded our operations primarily with proceeds from sales of equity securities and our borrowing under the Loan Agreement with Hercules. As of December 31, 2025, we had cash, cash equivalents and marketable securities of $1.1 billion.

In November 2021, we entered into an Open Market Sale AgreementSM, or the Sales Agreement, with Jefferies LLC, or Jefferies. On March 5, 2024, we filed a universal shelf registration statement on Form S-3, or the 2024 Shelf Registration Statement, pursuant to which we may offer and sell debt securities, common stock, preferred stock, units and/or warrants from time to time at an indeterminate aggregate offering price in one or more offerings. In November 2024, we filed a prospectus supplement relating to the Sales Agreement, pursuant to which, in accordance with the Sales Agreement, we may offer and sell shares of our common stock having an aggregate offering price of up to $300.0 million, which we refer to as our at-the-market offering program. Sales of common stock under the Sales Agreement through Jefferies may be made by any method that is deemed an “at-the-market” offering as defined in Rule 415(a)(4) under the Securities Act.

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During the year ended December 31, 2025, we issued and sold an aggregate of 10,660,159 shares of common stock pursuant to the Sales Agreement for aggregate net proceeds of $140.6 million, after deducting commissions and offering expenses payable by us. We sold such shares at a weighted average price of $13.60 per share.

In June 2025, we entered into the Loan Agreement with Hercules, in its capacity as administrative agent and collateral agent and as a lender, and certain other financial institutions that from time to time become parties to the Loan Agreement as lenders, which we refer to collectively as the Lenders. In December 2025, we entered into the First Amendment to the Loan Agreement with Hercules. The Loan Agreement, as amended by the First Amendment, provides for term loans in an aggregate principal amount of up to $275.0 million under multiple tranches, available as follows: (i) an initial term loan tranche funded on the closing date of the Loan Agreement in aggregate principal amount of $100.0 million; (ii) subject to the achievement of specified clinical, regulatory and commercial milestones, and after the borrowing of the second term loan tranche of $50.0 million in December 2025, two additional term loan tranches totaling up to $75.0 million; and (iii) subject to approval by the Lenders’ investment committee in their discretion, a final term loan tranche of up to $50.0 million. In the year ended December 31, 2025, we received net proceeds of $148.3 million from the first and second term loan tranches, after deducting debt issuance costs payable by us. Refer to Note 7, “Long-Term Debt” in the accompanying notes to the condensed consolidated financial statements for a discussion of the Loan Agreement with Hercules.

In July 2025, we completed a follow-on public offering, pursuant to which we issued and sold 27,878,788 shares of our common stock. We received net proceeds from the offering of $215.8 million, after deducting underwriting discounts and commissions and offering expenses paid by us.

In December 2025, we completed a follow-on public offering, pursuant to which we issued and sold 21,827,549 shares of our common stock. We received net proceeds from the offering of $377.7 million, after deducting underwriting discounts and commissions and offering expenses paid by us.

Cash flows

The following table summarizes our sources and uses of cash for each of the periods presented:

Year Ended December 31,

Net cash used in operating activities $ (403,207 ) $ (292,369 )

Net cash used in investing activities (28,751 ) (204,076 )

Net increase in cash, cash equivalents and restricted cash $ 458,349 $ 313,450

Operating activities

During the year ended December 31, 2025, operating activities used $403.2 million of cash, due to our net loss of $446.2 million and changes in our operating assets and liabilities of $3.4 million, partially offset by non-cash charges of $46.4 million. Net cash used in changes in our operating assets and liabilities primarily consisted of a $12.6 million increase in non-current assets, partially offset by an $8.3 million increase in accounts payable and other liabilities and a $1.0 million decrease in prepaid expenses and other current assets. During the year ended December 31, 2024, operating activities used $292.4 million of cash, due to our net loss of $317.4 million and changes in our operating assets and liabilities of $19.5 million, partially offset by non-cash charges of $44.5 million. Net cash used in changes in our operating assets and liabilities primarily consisted of a $9.0 million decrease in accounts payable and other liabilities and a $10.5 million increase in prepaid expenses and other current assets. Changes in our operating assets and liabilities during these periods were generally due to the growth of our business, increased clinical trial activity, increased manufacturing activities, advancement of our product candidates, the timing of vendor invoices and payments and annual bonus payments.

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Investing activities

During the year ended December 31, 2025, net cash used in investing activities was $28.8 million due to purchases of marketable securities of $180.5 million, an advance payment for long-lead equipment of $18.8 million and purchases of property and equipment of $1.9 million, partially offset by maturities of marketable securities of $154.6 million and sales of marketable securities of $17.9 million. During the year ended December 31, 2024, net cash used in investing activities was $204.1 million due to purchases of marketable securities of $317.4 million and purchases of property and equipment of $2.4 million, partially offset by maturities of marketable securities of $105.2 million and sales of marketable securities of $10.6 million

Financing activities

During the year ended December 31, 2025, net cash provided by financing activities was $890.3 million, consisting of $594.0 million in aggregate net proceeds from sales of common stock in our July 2025 and December 2025 offerings, $140.6 million in aggregate net proceeds from sales under our at-the-market offering program, $148.3 million in net proceeds from the first two tranches under the Loan Agreement with Hercules and $8.0 million in proceeds received from stock option exercises. These cash inflows were partially offset by $0.6 million in payment of debt issuance costs.

During the year ended December 31, 2024, net cash provided by financing activities was $809.9 million, consisting of $675.2 million in aggregate net proceeds from sales of common stock in our January 2024 and May 2024 offerings, $97.9 million in aggregate net proceeds from sales under our at-the-market offering program and $36.8 million in proceeds received from stock option exercises.

A discussion of changes in our financial condition for the year ended December 31, 2024 as compared to the year ended December 31, 2023 is included under the heading “Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations” in our Annual Report on Form 10-K for the year ended December 31, 2024, as filed with the SEC on February 27, 2025.

Funding requirements

We expect our expenses to increase in connection with our ongoing activities, particularly as we advance the clinical development of z-rostudirsen and z-basivarsen, the development of our FSHD and Pompe programs and additional research programs. The timing and amount of our operating expenditures will depend largely on:

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the identification of additional product candidates;

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the scope, progress, costs and results of preclinical and clinical development of any product candidates we may develop;

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the costs, timing and outcome of regulatory review of any product candidates we may develop;

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our decision to initiate a clinical trial, not to initiate a clinical trial or to terminate an existing clinical trial;

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changes in laws or regulations applicable to any product candidates we may develop, including but not limited to clinical trial requirements for approvals;

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the cost and timing of obtaining materials to produce adequate product supply for any preclinical or clinical development of any product candidate we may develop;

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the costs and timing of future commercialization activities, including product manufacturing, marketing, sales and distribution, for any product candidate we may develop for which we obtain marketing approval;

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the legal costs involved in prosecuting patent applications and enforcing patent claims and other intellectual property claims;

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additions or departures of key scientific or management personnel;

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our ability to establish and maintain collaborations on favorable terms, if at all, as well as the costs and timing of any collaboration, license or other arrangement, including the terms and timing of any milestone payments thereunder; and

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the costs of operating as a public company.

We believe that our existing cash, cash equivalents and marketable securities will enable us to fund our operating expenses, debt service obligations, and capital expenditure requirements into the first quarter of 2028. We have based this estimate on assumptions that may prove to be wrong, and we could exhaust our available capital resources sooner than we expect.

Until such time, if ever, as we can generate substantial product revenue, we expect to finance our cash needs through a combination of equity offerings, debt financings, collaborations, strategic alliances, and marketing, distribution or licensing arrangements with third parties. To the extent that we raise additional capital through the sale of equity or convertible debt securities, the ownership interest of our stockholders may be materially diluted, and the terms of such securities could include liquidation or other preferences that adversely affect the rights of holders of our common stock. Debt financing and preferred equity financing, if available, may involve agreements that include restrictive covenants that limit our ability to take specified actions, such as incurring additional debt, making capital expenditures or declaring dividends. If we raise funds through collaborations, strategic alliances or marketing, distribution or licensing arrangements with third parties, we may have to relinquish valuable rights to our technologies, future revenue streams, research programs or product candidates or grant licenses on terms that may not be favorable to us. We may be unable to raise additional funds or enter into such other agreements or arrangements when needed, on favorable terms, or at all. If we fail to raise capital or enter into such agreements other arrangements as and when needed, we may have to significantly delay, reduce or eliminate the development or future commercialization of one or more of our product candidates we may develop. See Item 1A. “Risk factors” in this Annual Report on Form 10-K for additional risks associated with our substantial capital requirements.

Contractual and other obligations

We enter into contracts in the normal course of business with CROs, CMOs and other third parties for preclinical research studies, clinical trials and testing and manufacturing services. Except for the master manufacturing services agreements described below, these contracts typically do not contain minimum purchase commitments and are generally cancelable by us upon written notice. Payments due upon cancellation consist of payments for services provided or expenses incurred, including noncancelable obligations of our service providers, up to the date of cancellation and in the case of certain arrangements with CROs and CMOs may include non-cancelable fees.

We have also entered into a license agreement with the University of Mons under which we are obligated to make specified milestone and royalty payments. The payment obligations under this agreement are contingent upon future events, such as our achievement of specified development, regulatory and commercial milestones, or generating product sales. We are unable to estimate the timing or likelihood of achieving these milestones or generating future product sales. For additional information about our license agreement with the University of Mons and amounts that could become payable in the future under that agreement, see Item 1. “Business—Intellectual Property—License Agreement with the University of Mons” in this Annual Report.

On December 4, 2020, we entered into a lease agreement for office and laboratory space, which was amended in January 2021, March 2021, and June 2021. The lease has a term of 8.5 years that commenced when we gained access to the office and laboratory space in September 2021. Our obligation for the payment of the base rent began in April 2022 and is $0.4 million per month, increasing to $0.5 million per month during the term of the lease. We have two options to extend the term of the lease, each for a period of an additional five years.

On January 15, 2025, we entered into a master manufacturing services agreement with a CMO which secures capacity at the CMO's manufacturing facilities for certain of our product candidates and

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components thereof. As of December 31, 2025, we have paid $31.2 million towards non-current assets under this agreement and pursuant to a mutually agreed rolling forecast we have committed to pay an additional $109.5 million in fees through December 2027. In specified termination circumstances, the agreement requires us to pay the CMO for services completed, the cost of the CMO's raw materials that cannot be repurposed and specified cancellation fees. This agreement formalizes and supersedes a letter agreement that we entered into with the CMO on July 18, 2024.

On October 31, 2025, we entered into another master manufacturing services agreement with a CMO which also secures capacity at the CMO's manufacturing facilities for certain of our product candidate components. The agreement obligates us to compensate the CMO for producing certain of our product candidate components pursuant to a mutually agreed rolling forecast. Upon execution, we committed to compensate the CMO at least $28.4 million in fees through March 2027. In specified termination circumstances, the agreement requires us to pay the CMO for services completed, the cost of the CMO's raw materials that cannot be repurposed, capital equipment and certain manufacturing activities previously committed to.

Critical accounting estimates

Our consolidated financial statements are prepared in accordance with generally accepted accounting principles in the United States. The preparation of our consolidated financial statements and related disclosures requires us to make estimates and judgments that affect the reported amounts of assets, liabilities, costs and expenses, and the disclosure of contingent assets and liabilities in our financial statements. We base our estimates on historical experience, known trends and events and various other factors that we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. We evaluate our estimates and assumptions on an ongoing basis. Our actual results may differ from these estimates under different assumptions or conditions.

We define our critical accounting policies as those accounting principles generally accepted in the United States of America that require us to make subjective estimates and judgments about matters that are uncertain and are likely to have a material impact on our financial condition and results of operations as well as the specific manner in which we apply those principles. Management has determined that our most critical accounting policies are those relating to accrued research and development expenses and stock-based compensation. As we advance our product candidates into and through clinical development, we expect research and development expenses and, in particular, our accounting for accrued research and development expenses to be an increasingly important critical accounting policy. We believe the following accounting estimates used in the preparation of our consolidated financial statements have the most significant level of estimation uncertainty and have and are reasonably likely to have a material impact on our financial condition and results of operations. For a more detailed description of our significant accounting policies, refer to Note 2, “Summary of Significant Accounting Policies,” in the accompanying notes to the consolidated financial statements.

Accrued research and development expenses

As part of the process of preparing our financial statements, we are required to estimate our accrued research and development expenses. This process involves reviewing open contracts and purchase orders, communicating with our service providers and applicable personnel to identify services that have been performed on our behalf and estimating the level of service performed and the associated cost incurred for the service when we have not yet been invoiced or otherwise notified of actual costs. The majority of our service providers invoice us in arrears for services performed, on a pre-determined schedule or when contractual milestones are met; however, some require advance payments. We make estimates of our accrued expenses as of each balance sheet date in the financial statements based on facts and circumstances known to us at that time. We periodically confirm the accuracy of these estimates with the service providers and make adjustments, if necessary. Examples of estimated accrued research and development expenses include fees paid to:

•

CROs in connection with the DELIVER and ACHIEVE clinical trials;

144

•

CROs and investigative sites in connection with research activities;

•

CMOs in connection with the production of research materials; and

•

vendors in connection with preclinical development activities.

We measure the expense recognized based on our estimates of the services received and efforts expended pursuant to quotes and contracts with multiple CMOs and CROs that supply, conduct and manage preclinical studies and clinical trials on our behalf. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows. There may be instances in which payments made to our vendors will exceed the level of services provided and result in a prepayment of the expense. Payments under some of these contracts depend on factors such as the successful enrollment of patients and the achievement of specified milestones. In accruing service fees, we estimate the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from the estimate, we adjust the accrual or the amount of prepaid expenses accordingly. Although we do not expect our estimates to be materially different from amounts actually incurred, if our estimates of the status and timing of services performed differ from the actual status and timing of services performed, it could result in us reporting amounts that are too high or too low in any particular period. To date, there have been no material differences between our estimates of such expenses and the amounts actually incurred.

Stock-based compensation

We measure stock-based awards granted to employees and directors based on fair value on the date of the grant using the Black-Scholes option-pricing model for options with service-based vesting, and we measure awards of restricted stock units based on the closing price of our common stock on the date of grant. Compensation expense for these awards is recognized over the requisite service period, which is generally the vesting period of the respective award. We use the straight-line method to record the expense of awards with service-based vesting conditions. We use the graded-vesting method to record the expense of awards with both service-based and performance-based vesting conditions, commencing when achievement of the performance condition becomes probable. In July 2025, we granted stock options with a combination of service-based vesting and the achievement of certain market conditions.

The fair value of each stock option grant with service-based vesting conditions is estimated on the date of grant using the Black-Scholes option-pricing model, which uses as inputs the fair value of our common stock and assumptions we make for the volatility of our common stock, the expected term of our stock options, the risk-free interest rate for a period that approximates the expected term of our stock options and our expected dividend yield. The fair value of market-based stock options is estimated using a Monte Carlo valuation method, incorporating various option pricing inputs.

Prior to our IPO, there was no public market for our common stock, and consequently, the estimated fair value of our common stock was determined by our board of directors as of the date of each option grant, with input from management, considering third-party valuations of our common stock as well as our board of directors’ assessment of additional objective and subjective factors that it believed were relevant and which may have changed from the date of the most recent third-party valuation through the date of the grant. Since our IPO, we have determined the fair market value of our common stock using the closing price of our common stock as reported on the Nasdaq Global Select Market.

Recently issued accounting pronouncements

Refer to Note 2, “Summary of Significant Accounting Policies,” in the accompanying notes to the consolidated financial statements for a discussion of significant accounting policies. There are no recently issued accounting pronouncements that have not yet been adopted that are expected to have a material impact on our financial statements.

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

Interest Rate Risk

We are exposed to interest rate market risk as part of our treasury and investment portfolio, which includes cash, cash equivalents, and marketable securities held in readily available checking and money market accounts, as well as debt securities. As part of our investment portfolio, we own financial instruments that are sensitive to market risks. The investment portfolio is used to preserve our capital, provide adequate liquidity and earn returns commensurate with our risk appetite. We invest in instruments that meet the credit quality standards outlined in our investment policy, which also limits the amount of credit exposure to any one issue or type of instrument. These instruments primarily include securities issued by the U.S. government and its agencies, investment-grade corporate bonds and commercial paper, certificates of deposit and money market funds. These investments are denominated in U.S. Dollars and none are held for trading purposes.

For the years ended December 31, 2025, 2024 and 2023, changes in interest rates did not have a material impact on our historical financial position, our business, our financial condition, our results of operations or our cash flows. Due to the short-term duration of our investment portfolio and the low risk profile of our investments, an immediate 10% change in interest rates would not have a material effect on the fair market value of our investment portfolio. However, there can be no assurance that changes in interest rates will not have a material adverse impact on us in the future.

Foreign Currency Exchange Risk

We are exposed to market risk related to changes in foreign currency exchange rates from contracts with vendors located outside of the United States, for which certain invoices are denominated in foreign currencies. We currently do not have a foreign currency hedging program. Changes in the relative values of currencies occur regularly and, in some instances, could materially adversely affect our business, our financial condition, our results of operations or our cash flows.

For the years ended December 31, 2025, 2024 and 2023, changes in foreign currency exchange rates did not have a material impact on our historical financial position, our business, our financial condition, our results of operations or our cash flows. Due to the relatively small number of contracts with vendors located outside of the United States denominated in foreign currencies, an immediate 10% change in a foreign currency exchange change would not have a material effect on our historical financial position, our business, our financial condition, our results of operations or our cash flows. However, there can be no assurance that changes in foreign currency exchange rates will not have a material adverse impact on us in the future.

Item 8. Financial Statements and Supplementary Data.

The financial statements required to be filed pursuant to this Item 8, together with the report of our independent registered public accounting firm, are appended to this Annual Report on Form 10-K. An index of those financial statements is found in Item 15 of Part IV of this Annual Report on Form 10-K.

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

None.

Item 9A. Controls and Procedures.

Evaluation of Disclosure Controls and Procedures

Our management, under the supervision and with the participation of our Chief Executive Officer and Chief Financial Officer (our principal executive officer and principal financial officer, respectively), evaluated the effectiveness of our disclosure controls and procedures as of December 31, 2025. The term “disclosure controls and procedures,” as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act means controls and other procedures of an issuer that are designed to ensure that information required to be disclosed by an issuer in the reports that it files or submits under the Exchange

146

Act is recorded, processed, summarized and reported, within the time periods specified in the SEC’s rules and forms. Disclosure controls and procedures include, without limitation, controls and procedures designed to ensure that information required to be disclosed by an issuer in the reports that it files or submits under the Exchange Act is accumulated and communicated to the issuer’s management, including its principal executive and principal financial officers, or persons performing similar functions, as appropriate to allow timely decisions regarding required disclosure.

Management recognizes that any disclosure controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving their objectives and management necessarily applies its judgment in evaluating the cost-benefit relationship of possible controls and procedures. Based on the evaluation of our disclosure controls and procedures as of December 31, 2025, our Chief Executive Officer and Chief Financial Officer concluded that, as of such date, our disclosure controls and procedures were effective at the reasonable assurance level.

Management’s Annual Report on Internal Control Over Financial Reporting

Our management is responsible for establishing and maintaining adequate internal control over financial reporting (as defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act). Our internal control over financial reporting is a process designed under the supervision of our principal executive and principal financial officer to provide reasonable assurance regarding the reliability of our financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. Management assessed our internal control over financial reporting as of December 31, 2025. Management based its assessment on criteria established in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission. Based on that evaluation, our management concluded that our internal control over financial reporting was effective as of December 31, 2025.

Deloitte & Touche LLP, the independent registered public accounting firm that audited the Consolidated Financial Statements included in this Annual Report on Form 10-K, has issued an audit report on the effectiveness of our internal control over financial reporting as of December 31, 2025, which is included herein.

Changes in Internal Control over Financial Reporting

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

147

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Stockholders and Board of Directors of Dyne Therapeutics, Inc.

Opinion on Internal Control over Financial Reporting

We have audited the internal control over financial reporting of Dyne Therapeutics, Inc. and subsidiary (the "Company") as of December 31, 2025, based on criteria established in Internal Control — Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO). In our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control — Integrated Framework (2013) issued by COSO.

We have also audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the consolidated financial statements as of and for the year ended December 31, 2025, of the Company and our report dated March 2, 2026, expressed an unqualified opinion on those financial statements.

Basis for Opinion

The Company's management is responsible for maintaining effective internal control over financial reporting and for its assessment of the effectiveness of internal control over financial reporting, included in the accompanying Management's Annual Report on Internal Control over Financial Reporting. Our responsibility is to express an opinion on the Company's internal control over financial reporting based on our audit. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audit in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether effective internal control over financial reporting was maintained in all material respects. Our audit included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, testing and evaluating the design and operating effectiveness of internal control based on the assessed risk, and performing such other procedures as we considered necessary in the circumstances. We believe that our audit provides a reasonable basis for our opinion.

Definition and Limitations of Internal Control over Financial Reporting

A company's 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 for external purposes in accordance with generally accepted accounting principles. A company's internal control over financial reporting includes those policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company's assets that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

/s/ Deloitte & Touche LLP

Boston, Massachusetts

March 2, 2026

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Item 9B. Other Information.

Director and Officer Trading Arrangements

None of our directors or officers (as defined in Rule 16a-1(f) under the Securities Exchange Act of 1934, as amended) adopted or terminated a Rule 10b5-1 trading arrangement or a non-Rule 10b5-1 trading arrangement (as defined in Item 408(c) of Regulation S-K) during the fourth quarter of 2025.

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspection

Not applicable.

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PART III

Item 10. Directors, Executive Officers and Corporate Governance.

Except to the extent provided below, the information required by this Item 10 will be included in our definitive proxy statement to be filed with the SEC with respect to our 2026 Annual Meeting of Stockholders which we intend to file not later than 120 days after the end of our fiscal year ended December 31, 2025 and is incorporated herein by reference.

We have adopted a written code of business conduct and ethics that applies to our directors, officers, employees and designated agents, including our principal executive officer, principal financial officer, principal accounting officer, or persons performing similar functions. A current copy of the code is posted on the investor relations section of our website, which is located at http://www.dyne-tx.com. If we make any substantive amendments to, or grant any waivers from, the code of business conduct and ethics for any officer or director, we will disclose the nature of such amendment or waiver on our website.

Item 11. Executive Compensation.

The information required by this Item 11 will be included in our definitive proxy statement to be filed with the SEC with respect to our 2026 Annual Meeting of Stockholders and is incorporated herein by reference.

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

The information required by this Item 12 will be included in our definitive proxy statement to be filed with the SEC with respect to our 2026 Annual Meeting of Stockholders and is incorporated herein by reference.

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

The information required by this Item 13 will be included in our definitive proxy statement to be filed with the SEC with respect to our 2026 Annual Meeting of Stockholders and is incorporated herein by reference.

Item 14. Principal Accounting Fees and Services.

The information required by this Item 14 will be included in our definitive proxy statement to be filed with the SEC with respect to our 2026 Annual Meeting of Stockholders and is incorporated herein by reference.

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PART IV

Item 15. Exhibits and Financial Statement Schedules.

(1) Consolidated Financial Statements

The following documents are included on pages F-1 through F-23 attached hereto and are filed as part of this Annual Report on Form 10-K.

Report of Independent Registered Public Accounting Firm (PCAOB ID No. 34) F-2

Consolidated Balance Sheets F-4

Consolidated Statements of Operations and Comprehensive Loss F-5

Consolidated Statements of Stockholders’ Equity F-6

Consolidated Statements of Cash Flows F-7

Notes to Consolidated Financial Statements F-8

(2) Financial Statement Schedules

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

(3) Exhibits

The following is a list of exhibits filed as part of this Annual Report on Form 10-K.

ExhibitNumber Description

151

10.17#* 2024 Inducement Stock Incentive Plan, as amended.

152

153

101.INS XBRL Instance Document

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

* Filed herewith.

† Portions of this exhibit have been omitted pursuant to Item 601(b)(10)(iv) of Regulation S-K.

# Management contract or compensatory plan or arrangement filed in response to Item 15(a)(3) of the Instructions to the Annual Report on Form 10-K.

Item 16. Form 10-K Summary

None.

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SIGNATURES

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

DYNE THERAPEUTICS, INC.

Date: March 2, 2026 By: /s/ John G. Cox

John G. Cox

President and Chief Executive Officer

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, this Report has been signed below by the following persons on behalf of the Registrant in the capacities and on the dates indicated.

Name Title Date

John G. Cox

Erick Lucera

/s/ Jason Rhodes Director and Chairman of the Board March 2, 2026

Jason Rhodes

/s/ Ed Hurwitz Director March 2, 2026

Ed Hurwitz

/s/ Carlo Incerti, M.D. Director March 2, 2026

Carlo Incerti, M.D.

/s/ Vikram Karnani Director March 2, 2026

Vikram Karnani

/s/ Dirk Kersten Director March 2, 2026

Dirk Kersten

/s/ David Lubner Director March 2, 2026

David Lubner

/s/ Brian Posner Director March 2, 2026

Brian Posner

/s/ Catherine Stehman-Breen, M.D. Director March 2, 2026

Catherine Stehman-Breen, M.D.

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Index to Consolidated Financial Statements

Report of Independent Registered Public Accounting Firm (PCAOB ID No. 34) F-2

Consolidated Balance Sheets F-4

Consolidated Statements of Operations and Comprehensive Loss F-5

Consolidated Statements of Stockholders’ Equity F-6

Consolidated Statements of Cash Flows F-7

Notes to Consolidated Financial Statements F-8

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Stockholders and Board of Directors of Dyne Therapeutics, Inc.

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of Dyne Therapeutics, Inc. and subsidiary (the "Company") as of December 31, 2025 and December 31, 2024, the related consolidated statements of operations and comprehensive loss, stockholders' equity, and cash flows, for each of the three years in the period ended December 31, 2025, and the related notes (collectively referred to as the "financial statements"). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and December 31, 2024, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2025, in conformity with accounting principles generally accepted in the United States of America.

We have also audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the Company's internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control — Integrated Framework (2013)issued by the Committee of Sponsoring Organizations of the Treadway Commission and our report dated March 2, 2026, expressed an unqualified opinion on the Company's internal control over financial reporting.

Basis for Opinion

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

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matter

The critical audit matter communicated below is a matter arising from the current-period audit of the financial statements that was communicated or required to be communicated to the audit committee and that (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

Accrued and Prepaid Research and Development Expense - Refer to Note 2 and 6 to the financial statements

Critical Audit Matter Description

F-2

The Company records accrued expenses and prepaid expenses associated with ongoing research and development costs, including costs associated with outsourced agreements for clinical trials with contract research organizations (CROs) and production of research materials with contract manufacturing organizations (CMOs). Estimates of expenses incurred are determined by analyzing progress of the studies, including phase or completion of events, invoices received, payments made, communication with third-party CROs and CMOs, and internal tracking of work completed to date. Expenses incurred in excess of amounts invoiced are recorded as accrued expenses. Payments made in excess of expenses incurred are recorded as prepaid costs. We note that these balances are included in “Accrued Expenses” and “Prepaid expenses and other current assets,” respectively, in the financial statements. We identified auditing the estimates of the extent of work performed by CROs and CMOs as a critical audit matter because of the level of management judgment required and volume of such estimates made by management. This required a high degree of auditor judgment and an increased extent of effort when performing audit procedures to evaluate the reasonableness of management’s estimates.

How the Critical Audit Matter Was Addressed in the Audit

Our audit procedures related to accrued and prepaid research and development expenses included the following, among others:

•

We tested the design and effectiveness of controls over the estimation of accrued and prepaid research and development expenses.

•

For a sample of studies and clinical trials, we performed the following:

▪

Inspected the related contracts, purchase orders, statements of work and other contractual documentation.

▪

Tested the completeness and accuracy of the underlying data used to develop the estimates.

▪

Performed corroborating inquiries with the Company’s research and development personnel.

▪

Inspected information from third-party service providers to understand the nature and progress of the studies.

▪

Obtained corresponding invoices and evidence of payment to third-party service providers.

/s/ Deloitte & Touche LLP

Boston, Massachusetts

March 2, 2026

We have served as the Company's auditor since 2020.

F-3

Dyne Therapeutics, Inc.

Consolidated Balance Sheets

December 31,

(in thousands, except share and per share data) 2025 2024

Assets

Current assets:

Prepaid expenses and other current assets 16,025 17,011

Liabilities and Stockholders’ Equity

Current liabilities:

Accrued expenses and other current liabilities 37,548 30,846

Lease liabilities, net of current portion 15,283 19,138

Stockholders’ equity

Accumulated other comprehensive gain 475 6

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

F-4

Dyne Therapeutics, Inc.

Consolidated Statements of Operations and Comprehensive Loss

Year Ended December 31,

(in thousands, except share and per share data) 2025 2024 2023

Operating expenses:

Other (expense) income:

Interest expense (6,192 ) — —

Net loss per share, basic and diluted $ (3.47 ) $ (3.37 ) $ (3.95 )

Comprehensive loss:

Other comprehensive loss:

Unrealized gains on marketable securities, net 469 6 571

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

F-5

Dyne Therapeutics, Inc.

Consolidated Statements of Stockholders’ Equity

(in thousands, except share data) Shares Amount

Vesting of restricted stock units 490,269 — — — — —

Unrealized gains on marketable securities — — — 571 — 571

Vesting of restricted stock units 1,070,788 — — — — —

Unrealized gains on marketable securities — — — 6 — 6

Vesting of restricted stock units 1,274,489 — — — — —

Unrealized gains on marketable securities — — — 469 — 469

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

F-6

Dyne Therapeutics, Inc.

Consolidated Statements of Cash Flows

Year Ended December 31,

Cash flows from operating activities:

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

Accretion of discount on marketable securities (1,835 ) (3,604 ) (1,102 )

Loss (gain) on sale of marketable securities (30 ) (35 ) 23

Non-cash interest expense 118 — —

Loss on disposal of property and equipment 95 72 118

Changes in operating assets and liabilities:

Prepaid expenses and other current assets 986 (10,536 ) 3,337

Other non-current assets (12,641 ) — —

Cash flows from investing activities:

Purchases of property and equipment (1,920 ) (2,376 ) (729 )

Advance payment for long-lead equipment (18,790 ) — —

Cash flows from financing activities:

Proceeds from issuance of long-term debt, net of issuance costs paid 148,256 — —

Payment of debt issuance costs (558 ) — —

Supplemental disclosures of cash flow information:

Purchase of property and equipment in accounts payable $ 65 $ — $ 12

Cash paid for interest 4,339 — —

Debt issuance costs included in accounts payable or accrued expenses 30 — —

Offering costs included in accounts payable or accrued expenses 424 — —

Proceeds from employee stock option exercise in other receivables — 199 —

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

F-7

Dyne Therapeutics, Inc.

Notes to Consolidated Financial Statements

1. Nature of Business and Basis of Presentation

Dyne Therapeutics, Inc. (the “Company”) is a clinical-stage neuromuscular disease company focused on delivering functional improvement for people living with genetically driven neuromuscular diseases. The Company was incorporated in Delaware on December 1, 2017, and has a principal place of business in Waltham, Massachusetts.

The Company is subject to risks and uncertainties common to clinical-stage companies in the biotechnology industry, including, but not limited to, development by competitors of new technological innovations, dependence on key personnel, protection of proprietary technology, risks of failure of preclinical studies and clinical trials, the need to obtain marketing approval for its product candidates, fluctuations in operating results, compliance with government regulations, the ability to establish clinical- and commercial-scale manufacturing processes and the ability to secure additional capital to fund operations. Product candidates and programs currently under development require significant research and development efforts, including extensive preclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities. Even if the Company’s development efforts are successful and product candidates receive regulatory approval, it is uncertain when, if ever, the Company will realize significant revenue from product sales.

The accompanying consolidated financial statements have been prepared on the basis of continuity of operations, realization of assets and the satisfaction of liabilities and commitments in the ordinary course of business. Since inception, the Company has funded its operations with proceeds from the sales of equity securities and its term loan with Hercules Capital, Inc. ("Hercules"). The Company expects to continue to generate operating losses for the foreseeable future. The Company expects that its cash, cash equivalents, and marketable securities will be sufficient to fund its operating expenses and capital expenditure requirements for at least 12 months from the issuance of these consolidated financial statements.

To continue its development efforts, the Company will need to obtain substantial additional funding through public or private equity offerings, debt financings, collaborations, strategic alliances and/or licensing arrangements in order to fund its research and development and ongoing operating expenses. The Company may not be able to obtain financing on acceptable terms, when needed or at all, and the Company may not be able to enter into collaborations, strategic alliances or licensing arrangements. The terms of any financing may adversely affect the holdings or the rights of the Company’s stockholders. Any collaborations, strategic alliances or licensing arrangements may require the Company to relinquish rights to certain of its technologies, future revenue streams, research programs or product candidates or grant licenses on terms that may not be favorable to the Company. If the Company is unable to obtain funding, the Company could be forced to delay, limit, reduce or eliminate some or all of its research and development programs, pipeline expansion or future commercialization efforts or grant rights to develop and market product candidates, which could adversely affect its business prospects. Although management will continue to pursue these plans, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations when needed or at all.

2. Summary of Significant Accounting Policies

The accompanying consolidated financial statements reflect the operations of the Company and the Company’s wholly-owned subsidiary, Dyne Therapeutics Securities Corporation. Intercompany balances and transactions have been eliminated in consolidation. The accompanying consolidated financial statements have been prepared in conformity with generally accepted accounting principles (“GAAP”) in the United States of America. Any reference in these notes to applicable guidance is meant to refer to the

F-8

authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”).

Use of estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, the accrual of research and development expenses and stock-based compensation expense. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates, as there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results may differ from those estimates or assumptions.

Concentrations of credit risk and of significant suppliers

Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents and marketable securities. The Company believes the depository institutions in which the cash and cash equivalents are held are of high-credit quality. The Company has adopted an investment policy that limits the amounts the Company may invest in the securities of any single issuer with the exclusion of the U.S. government. The Company has not experienced any credit losses.

The Company is dependent on a small number of third-party suppliers for its drug substance and drug product. In particular, the Company relies, and expects to continue to rely, on third-party suppliers for certain materials and components required for the development of its programs and future production of any product candidates it may develop for its programs. These programs could be adversely affected by a significant interruption in the supply process.

Marketable securities

The Company’s marketable securities consist of commercial paper, certificates of deposit, U.S. Treasury notes and corporate debt securities and are classified as available-for-sale which are reported at fair value. Unrealized gains or losses on available-for-sale debt securities are reported as a component of accumulated other comprehensive loss in stockholders’ equity. Realized gains and losses are based on the specific identification method and are included as a component of other income (expense), net in the consolidated statements of operations and comprehensive loss.

The Company evaluates its marketable securities with unrealized losses for other-than-temporary impairment. When assessing marketable securities for other-than-temporary declines in value, the Company considers such factors as, among other things, how significant the decline in value is as a percentage of the original cost, how long the market value of the investment has been less than its original cost, the Company’s ability and intent to retain the investment for a period of time sufficient to allow for any anticipated recovery in fair value and market conditions in general. If any adjustment to fair value reflects a decline in the value of the investment that the Company considers to be “other than temporary,” the Company reduces the investment to fair value through a charge to the statement of operations and comprehensive loss. No such adjustments were necessary during the periods presented.

Leases

At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on the unique facts and circumstances presented in the arrangement, including whether the Company controls the use of identified assets. The Company classifies leases with a term greater than one year as either operating or finance leases at the lease commencement date and records a right-of-use assets and current and non-current lease liabilities, as applicable on the balance sheet. The Company has elected not to recognize on the balance sheet leases with terms of one year or less. For

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these leases, payments are recognized as expense on a straight-line basis over the lease term. If a lease includes options to extend the lease term, the Company does not assume the option will be exercised in its initial lease term assessment unless there is reasonable certainty that the Company will renew based on an assessment of economic factors present as of the lease commencement date. The Company monitors its plans to renew its material lease each reporting period.

Lease liabilities and the corresponding right-of-use assets are recorded based on the present value of lease payments over the remaining lease term. The present value of future lease payments are discounted using the interest rate implicit in lease contracts if that rate is readily determinable; otherwise the Company utilizes its incremental borrowing rate (“IBR”), which reflects the fixed rate at which the Company could borrow on a collateralized basis over a similar term, the amount of the lease payments in a similar economic environment. After lease commencement and the establishment of a right-to-use asset and operating lease liability, lease expense is recorded on a straight-line basis over the lease term.

The Company enters into contracts that contain both lease and non-lease components. Non-lease components include costs that do not provide a right-to-use a leased asset but instead provide a service, such as maintenance costs. The Company has elected to account for the lease and non-lease components together as a single component for all classes of underlying assets for its operating leases. Variable costs associated with the lease, such as maintenance and utilities, are not included in the measurement of right-to-use assets and lease liabilities but rather are expensed when the events determining the amount of variable consideration to be paid have occurred.

Property and equipment

Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization expense is recognized using the straight-line method over the estimated useful life of each asset class.

Costs for capital assets not yet placed into service are capitalized as construction-in-process and depreciated once placed into service. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation and amortization are removed from the accounts and any resulting gain or loss is included in loss from operations. Expenditures for repairs and maintenance which do not improve or extend the life of the respective assets are charged to expense as incurred.

Impairment of long-lived assets

Long-lived assets consist of property and equipment. The Company evaluates the recoverability of its long-lived assets when circumstances indicate that an event of impairment may have occurred. The Company recognizes an impairment loss only if the carrying amount of a long-lived asset is not recoverable based on its undiscounted future cash flows. Impairment is measured based on the difference between the carrying value of the related assets and the fair value of such assets. The Company has not recorded any impairment charges in the periods presented in these financial statements.

Segment information

Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker, or decision-making group, in making decisions on how to allocate resources and assess performance. The Company’s chief operating decision maker is the chief executive officer (“CEO”). The CEO views the Company’s operations and manages the business as one operating segment.

Research and development costs

Research and development costs are expensed as incurred. Research and development expenses consist of costs incurred in performing research and development activities, including salaries and bonuses, stock-based compensation, employee benefits, facilities costs, laboratory supplies, depreciation

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and amortization, manufacturing expenses and external costs of vendors engaged to conduct clinical and preclinical development activities as well as the cost of licensing technology.

Upfront payments and milestone payments made for the licensing of technology are expensed as research and development expenses in the period in which they are incurred. Advance payments for goods or services to be received in the future for use in research and development activities are recorded as prepaid expenses. The prepaid amounts are expensed as the related goods are consumed or the services are performed.

Research and manufacturing contract costs and accruals

The Company has entered into various research and development and manufacturing contracts. These agreements are generally cancelable, and related payments are recorded as the corresponding expenses are incurred. The Company records accruals for estimated ongoing costs. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the research studies and manufacturing activities, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical accrual estimates have not been materially different from the actual costs.

Patent costs

All patent-related costs incurred in connection with filing and prosecuting patent applications are expensed as incurred due to the uncertainty about the recovery of the expenditure. Amounts incurred are classified as general and administrative expenses.

Income taxes

The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the financial statements or in the Company’s tax returns. Deferred taxes are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect in the years in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes, based upon the weight of available evidence, that it is more likely than not that all or a portion of the deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense. Potential for recovery of deferred tax assets is evaluated by estimating the future taxable profits expected and considering prudent and feasible tax planning strategies.

The Company accounts for uncertainty in income taxes recognized in the financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more-likely-than-not to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties.

Fair value measurements

Certain assets and liabilities are carried at fair value. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at

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fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable:

•

Level 1—Unadjusted quoted prices in active markets that are accessible to the reporting entity at the measurement date for identical assets and liabilities.

•

Level 2—Inputs other than quoted prices in active markets for identical assets and liabilities that are observable either directly or indirectly for substantially the full term of the asset or liability. Level 2 inputs include the following:

•

quoted prices for similar assets and liabilities in active markets;

•

quoted prices for identical or similar assets or liabilities in markets that are not active;

•

observable inputs other than quoted prices that are used in the valuation of the asset or liabilities (e.g., interest rate and yield curve quotes at commonly quoted intervals); and

•

inputs that are derived principally from or corroborated by observable market data by correlation or other means.

•

Level 3—Unobservable inputs for the assets or liability (i.e., supported by little or no market activity). Level 3 inputs include management’s own assumptions about the assumptions that market participants would use in pricing the asset or liability (including assumptions about risk).

Net loss per share

Basic net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding for the period. Diluted net loss is computed by adjusting net loss to reallocate undistributed earnings based on the potential impact of dilutive securities. Diluted net loss per share is computed by dividing the diluted net loss by the weighted average number of shares of common stock outstanding for the period, including potential dilutive common shares assuming the dilutive effect of common stock equivalents.

The following potentially dilutive common stock equivalents, presented based on amounts outstanding at each period end, were excluded from the computation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect:

Year Ended December 31,

Stock-based compensation

The Company accounts for stock option awards at fair value and measures fair value using the Black-Scholes option-pricing model as of the grant date. For restricted stock unit awards, the fair value is based on the closing price of the Company's common stock on the date of grant. Stock-based compensation costs are recognized as expense over the requisite service period, which is generally the vesting period, on a straight-line basis for all time-vested awards. Forfeitures are recognized as they occur for all awards. For stock option awards with market-based vesting conditions, the fair value is estimated using a Monte Carlo valuation method, incorporating various option pricing inputs and expense is recognized over the remaining service period.

Comprehensive loss

Comprehensive loss includes net loss as well as other changes in stockholders’ equity that result from transactions and economic events other than those with stockholders. The Company’s only element of other comprehensive loss was unrealized gains (losses) on marketable securities.

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Recently Issued Accounting Pronouncements Not Yet Adopted

In November 2024, the FASB issued ASU 2024-03, Income Statement-Reporting Comprehensive Income-Expense Disaggregation Disclosures (Topic 220-40). The amendments in this update require new disclosures to disaggregate prescribed natural expenses underlying any income statement caption. ASU 2024-03 is effective for annual periods in fiscal years beginning after December 15, 2026, and interim periods thereafter. Early adoption is permitted. ASU 2024-03 applies on a prospective basis for periods beginning after the effective date. However, retrospective application to any or all prior periods presented is permitted. We are currently assessing the impact ASU 2024-03 will have on the consolidated financial statements and disclosures.

Recently Adopted Accounting Pronouncements

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740). The amendments in this update require enhanced annual income tax disclosures for the effective tax rate reconciliation and income taxes paid. The amendments are effective for the Company in the consolidated financial statements for the year ended December 31, 2025. The Company adopted this ASU for the annual period ended December 31, 2025 and the amendments have been applied retrospectively to all prior periods presented in the financial statements within the footnote disclosure of the reconciliation of the U.S. federal statutory income tax rate to the Company’s effective income tax rate. Refer to the rate reconciliation in Note 9 - Income Taxes for more information.

3. Cash, Cash Equivalents and Restricted Cash

Cash includes cash in readily available checking accounts and cash equivalents include money market funds that invest in U.S. Treasury securities and all highly liquid investments maturing within 90 days from the date of purchase.

Amounts included in restricted cash represent amounts pledged as collateral for letters of credit required for security deposits on the Company’s leased facilities.

Cash, cash equivalents and restricted cash consisted of the following:

December 31, December 31,

4. Fair Value Measurements

The following tables set forth marketable securities for the periods presented:

(in thousands) Amortized Cost Unrealized Gains Unrealized Losses Total

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(in thousands) Amortized Cost Unrealized Gains Unrealized Losses Total

The following tables set forth by level, within the fair value hierarchy (see Note 2), the assets carried at fair value on a recurring basis for the periods presented:

Fair Value Measurements as of December 31, 2025

(in thousands) Level 1 Level 2 Level 3 Total

Assets:

Cash equivalents

Marketable securities

Fair Value Measurements as of December 31, 2024

(in thousands) Level 1 Level 2 Level 3 Total

Assets:

Cash equivalents

Money market funds $ 3,535 $ — $ — $ 3,535

Marketable securities

The fair value of U.S. government Treasury notes and money market funds were determined by the Company based on quoted market prices, which represent a Level 1 measurement within the fair value hierarchy. Commercial paper, certificates of deposit and corporate debt securities were valued by the Company using quoted prices in active markets for similar securities, which represent a Level 2 measurement within the fair value hierarchy.

There were no transfers between Level 1, Level 2, or Level 3 during the periods presented.

The following table summarizes the scheduled maturity for the Company's marketable securities for the periods presented:

(in thousands) December 31,

Maturing in one year or less $ 156,029

Maturing after one year through two years 61,164

Maturing after two years —

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Financial instruments not recorded at fair value

The carrying values of cash, cash equivalents, accounts payable and accrued expenses that are reported on the balance sheets approximate their fair value due to the short-term nature of these assets and liabilities. The carrying amount of the Company's Term Loans under the Hercules Agreement, as defined in Note 7, approximate market rates currently available to the Company.

5. Property and Equipment

Property and equipment consisted of the following:

December 31,

Office and computer equipment 2,548 2,355

Less accumulated depreciation and amortization (8,721 ) (6,773 )

As of December 31, 2025, the Company was deemed to be the owner, for accounting purposes, of $18.8 million of long-lead equipment to be utilized for future manufacturing at a contract manufacturing organization ("CMO") facility.

Depreciation expense totaled $2.0 million, $1.7 million and $1.7 million for the years ended December 31, 2025, 2024, and 2023 respectively.

6. Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following:

December 31,

7. Long-Term Debt

On June 27, 2025 (the “Closing Date”), the Company entered into the loan agreement with Hercules (as subsequently amended, the “Loan Agreement”), in its capacity as administrative agent and collateral agent (the “Agent”) and as a lender, and certain other financial institutions that from time to time become parties to the Loan Agreement as lenders (collectively, the “Lenders”). On December 8, 2025, the Company entered into the First Amendment to the Loan Agreement with Hercules. The Loan Agreement, as amended by the First Amendment, provides for term loans in an aggregate principal amount of up to $275.0 million under multiple tranches (the “Term Loans”), available as follows: (i) an initial term loan tranche funded on the Closing Date in aggregate principal amount of $100.0 million (the “Initial Tranche”); (ii) subject to the achievement of specified clinical, regulatory and commercial milestones, three additional term loan tranches totaling up to $125.0 million; and (iii) subject to approval by the Lenders’ investment committee, in their discretion, a final term loan tranche of up to $50.0 million.

All unpaid principal and accrued and unpaid interest with respect to the Term Loans is due and payable in full on July 1, 2030 (the “Maturity Date”). The outstanding principal balance of the Term Loans bears

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interest at a floating interest rate per annum equal to the Wall Street Journal prime rate, subject to a floor of 7.50%, plus 2.45%. Accrued interest on the outstanding Term Loans is payable monthly. The Company may make payments of interest only until July 1, 2029. The interest only period may be extended until the Maturity Date upon the achievement of specified clinical, regulatory and commercial milestones. At the end of the interest only period, the Company is required to begin repayment of the outstanding principal of the Term Loans in equal monthly installments (or, in a single installment, if the interest-only period has been extended to the Maturity Date).

As collateral for the obligations under the Loan Agreement, the Company has granted to the Agent, for the benefit of the Lenders, a first-priority security interest in substantially all of its property, inclusive of intellectual property, subject to customary permitted liens and other exceptions set forth in the Loan Agreement.

The Loan Agreement contains customary representations and warranties, events of default and affirmative and negative covenants, including a minimum cash covenant (the “Minimum Cash Covenant”) requiring the Company to maintain specified levels of cash in accounts subject to a control agreement in favor of the Agent (“Qualified Cash”) during the period commencing on January 1, 2027. The Minimum Cash Covenant will initially be set at 60% of the then outstanding principal balance of the Term Loans, is subject to adjustment and will not be tested at any time when the Company’s market capitalization is greater than $1.65 billion. The Company is also required to maintain minimum net product revenue from the sale of z-rostudirsen and z-basivarsen starting nine months after U.S. Food and Drug Administration approval of z-rostudirsen or z-basivarsen (the “Minimum Revenue Covenant”) if the outstanding principal balance of the Term Loans exceeds $100.0 million. The Minimum Revenue Covenant will not be tested for any month to the extent that for each day during such month either (i) Qualified Cash is at least 100% of the Company’s outstanding obligations under the Loan Agreement or (ii) the Company’s market capitalization is greater than $1.65 billion and Qualified Cash is at least 50% of the Company’s outstanding obligations under the Loan Agreement. Certain negative covenants under the Loan Agreement limit the ability of the Company, among other things, to incur future debt, grant liens, make investments, make acquisitions, distribute dividends and sell assets, subject in each case to certain exceptions.

Upon the occurrence of an event of default, including the failure by the Company to comply with the covenants under the Loan Agreement or the occurrence of a material adverse effect on the business, operations, properties, assets or financial condition of the Company, in each case subject to certain exceptions, and subject to any specified cure periods, all amounts owed by the Company under the Loan Agreement may be declared immediately due and payable by the Agent, and the Agent may foreclose on collateral.

The Loan Agreement requires the Company to pay closing fees, prepayment penalties and an end-of-term charge equal to 5.5% of the amount of Term Loans borrowed, which amount is due at the earlier of prepayment or the Maturity Date. A prepayment penalty applies to any prepayment of the Term Loans prior to the Maturity Date equal to (i) 2.0% of the principal amount prepaid if the prepayment occurs on or prior to the first anniversary of the Closing Date, (ii) 1.5% of the principal amount prepaid if the prepayment occurs after the first anniversary and on or prior to the second anniversary of the Closing Date, and (iii) 0.75% of the principal amount prepaid if the prepayment occurs after the second anniversary through the day before the Maturity Date.

In connection with the execution of the First Amendment to the Loan Agreement, the Company borrowed a second term loan tranche in an aggregate principal amount of $50.0 million. During the year ended December 31, 2025, the average interest rate for the loan was 9.95%.

Unamortized debt discount and issuance costs were recorded as a reduction of the carrying amount on the Term Loans and are amortized as interest expense using the effective-interest method. The Company recorded total debt discount and debt issuance costs of $1.6 million as of December 31, 2025. The Company is accruing the end-of-term charge on its consolidated balance sheet. During the year ended December 31, 2025, the effective interest rate for the loan was 11.5%.

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In addition, debt issuance costs of $0.5 million were recorded in restricted cash and other assets as of December 31, 2025.

As of December 31, 2025, the carrying value of the Term Loans approximates its fair value.

The obligations under the Term Loans as of December 31, 2025 consisted of the following (in thousands):

December 31,

Principal term loan balance $ 150,000

Unamortized debt discount and issuance costs (1,625 )

Accrued end of term fee 546

The annual principal payments due under the Term Loans as of December 31, 2025 were as follows:

Year ending December 31, (in thousands)

The table of future principal payments excludes the end-of-term charge of 5.5% of the principal amount of the Term Loans borrowed, which is due upon the maturity of the Term Loans.

8. Stockholders' Equity

Common Stock

In November 2021, the Company entered into an Open Market Sale Agreement (the "Sales Agreement") with Jefferies LLC ("Jefferies") as the Company's sales agent. On March 5, 2024, the Company filed a universal shelf registration statement on Form S-3, (the “2024 Shelf Registration Statement”), and included a prospectus relating to the Sales Agreement. Under the 2024 Shelf Registration Statement, the Company may offer and sell debt securities, common stock, preferred stock, units and/or warrants from time to time at an indeterminate aggregate offering price in one or more offerings. In November 2024, the Company filed a prospectus supplement relating to the Sales Agreement, pursuant to which, in accordance with the Sales Agreement, the Company may offer and sell shares of its common stock having an aggregate offering price of up to $300.0 million in an “at-the-market” offering.



During the year ended December 31, 2025, the Company issued and sold an aggregate of 10,660,159 shares of common stock pursuant to the Sales Agreement for aggregate net proceeds of $140.6 million, after deducting commissions and offering expenses payable by the Company. The Company sold such shares at a weighted average price of $13.60 per share.

Atlas Venture and related affiliated entities were beneficial owners of approximately 5.5% of the Company's outstanding common stock as of December 31, 2025. The chairman of the Company's board of directors is a partner at Atlas Venture. On January 27, 2025, the Company issued and sold 1,111,111 shares of common stock through its at-the-market offering program that Atlas Venture and related affiliated entities purchased at a purchase price of $13.50 per share for aggregate gross proceeds of $15.0 million. The shares were purchased at the prevailing market price.

In July 2025, the Company completed a follow-on public offering, pursuant to which the Company issued

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and sold 27,878,788 shares of the Company's common stock. The Company received net proceeds of $215.8 million, after deducting underwriting discounts and commissions and offering expenses paid by the Company.

In December 2025, the Company completed a follow-on public offering, pursuant to which the Company issued and sold 21,827,549 shares of the Company's common stock. The Company received net proceeds of $377.7 million, after deducting underwriting discounts and commissions and offering expenses paid by the Company.

2020 Stock Incentive Plan

In August 2020 the Company’s board of directors adopted and the Company’s stockholders approved the 2020 Stock Incentive Plan (the "2020 Plan"), which became effective on September 16, 2020. The 2020 Plan provides for the grant of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock units and other stock-based awards to employees, directors, consultants and advisors of the Company. The 2020 Plan is administered by the Company’s board of directors or by a committee appointed by the board of directors. Upon the effectiveness of the 2020 Plan, the Company ceased granting awards under the 2018 Stock Incentive Plan. The number of shares initially reserved for issuance under the 2020 Plan was 4,884,233. The number of shares of common stock reserved for issuance under the 2020 Plan may automatically increase on the first day of each fiscal year, beginning with the fiscal year commencing on January 1, 2021, and continuing for each fiscal year until, and including the fiscal year commencing on, January 1, 2030, in an amount equal to the lower of (1) 5% of the shares of common stock outstanding on such date and (2) an amount determined by the Company’s board of directors. On January 1, 2026, 8,247,527 shares were added to the shares reserved for issuance under the 2020 Plan in the sixth of these annual increases.

As of December 31, 2025, 5,391,268 shares remained available for future issuance under the 2020 Plan.

2020 Employee Stock Purchase Plan

In August 2020 the Company’s board of directors adopted and the Company’s stockholders approved the 2020 Employee Stock Purchase Plan (the “2020 ESPP”), which became effective September 16, 2020. The 2020 ESPP is administered by the Company’s board of directors or by a committee appointed by the board of directors. The 2020 ESPP initially provides participating employees with the opportunity to purchase up to an aggregate of 488,414 shares of common stock. The number of shares of common stock reserved for issuance under the 2020 ESPP may automatically increase on the first day of each fiscal year, beginning with the fiscal year commencing on January 1, 2021 and continuing for each fiscal year until, and including the fiscal year commencing on, January 1, 2030, in an amount equal to the lowest of (1) 1,953,656 shares of common stock, (2) 1% of the shares of common stock outstanding on such date, and (3) an amount determined by the board of directors.

As of December 31, 2025, no offering periods have commenced under the 2020 ESPP and 488,414 shares remained available for issuance.

2024 Inducement Stock Incentive Plan

In March 2024, the Company's board of directors adopted the 2024 Inducement Stock Incentive Plan (the "2024 Inducement Plan"). The 2024 Inducement Plan provides for the grant of nonstatutory stock options, stock appreciation rights, restricted stock, restricted stock units and other stock-based awards with respect to an aggregate of 900,000 shares of Common Stock (subject to adjustment as provided in the 2024 Inducement Plan). Awards under the 2024 Inducement Plan may only be granted to new employees who were not previously an employee or director of the Company or are commencing employment with the Company following a bona fide period of non-employment, in either case, as an inducement material to the individual’s entering into employment with the Company and in accordance with the requirements of Nasdaq Stock Market Rule 5635(c)(4). In February 2025, the Company's board of directors approved an additional 1,000,000 shares for issuance under the 2024 Inducement Plan. During the year ended December 31, 2025, the Company granted inducement equity awards to four new employees as a

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material inducement to acceptance of their respective employment consisting of stock options to purchase up to an aggregate of 544,700 shares of the Company's common stock and restricted stock units with respect to an aggregate of 168,000 shares of the Company's common stock.

As of December 31, 2025, 440,447shares remained available for future issuance under the 2024 Inducement Plan.

Stock option valuation

The fair value of stock option grants is estimated using the Black-Scholes option-pricing model for stock options with service-based vesting conditions. The fair value is determined based upon the quoted price of the Company’s common stock. The Company lacks company-specific historical and implied volatility information. Therefore, it estimates its expected stock volatility based on the historical volatility of a publicly traded set of peer companies and expects to continue to do so until such time as it has adequate historical data regarding the volatility of its own traded stock price. For options with service-based vesting conditions, the expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. The fair value of market-based stock options is estimated using a Monte Carlo valuation method, incorporating various option pricing inputs.

The assumptions that the Company used to determine the grant-date fair value of options granted were as follows:

Year Ended December 31,