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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 financial statements and related notes appearing elsewhere in 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 these forward-looking statements.

Overview

We are a life sciences company focused on advancing a portfolio of current and future gene therapy candidates, which we refer to collectively as our Candidates, including SGT-003 for the treatment of Duchenne muscular dystrophy, or Duchenne, SGT-212 for the treatment of Friedreich's ataxia, or FA, SGT-501 for the treatment of Catecholaminergic polymorphic ventricular tachycardia, or CPVT, SGT-601 for the treatment of TNNT2-mediated dilated cardiomyopathy, or TNNT2 DCM, and additional assets for the treatment of genetic cardiac and other diseases, at different stages of development, with varying levels of investment. We are advancing our diverse pipeline across rare neuromuscular and cardiac diseases, bringing together experts in science, technology, disease management and care. Patient-focused and founded by those directly impacted by Duchenne, our mission is to improve the daily lives of patients living with these devastating diseases.

Solid was purpose-built to advance the best science and accelerate the discovery and development of treatments that may benefit all patients with Duchenne. As we expand to bring meaningful treatments to patients living with other neuromuscular and cardiac diseases, the values and guiding principles that drive us continue. Our corporate vision is to build an innovation platform enabling the discovery and development of high-value genetic medicines for neuromuscular and cardiac diseases by integrating internal capabilities, including a vector core, use of validated animal models, optimized expression cassettes, novel capsids and regulatory expertise, and collaborations with leaders in related clinical and research fields. Our mission, which guides our operations, is to treat and change the course of neuromuscular and cardiac diseases at all stages. Underscoring this mission, our disease-focused business model is founded on the following fundamental principles:

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identify and develop meaningful therapies for underserved patients with sometimes fatal neuromuscular and cardiac diseases;

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build innovative libraries of delivery capsids and other enabling technologies with the potential to have broad impact on the gene therapy field at large:

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bring together the leading experts in neuromuscular and cardiac diseases, science, technology, disease management and care; and

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be guided by the needs of these patients.

We are continuing to advance our pipeline of Candidates. The U.S. Food and Drug Administration, or the FDA, has granted orphan drug designation, Rare Pediatric Disease designation and Fast Track designation for SGT-003 for Duchenne. The FDA has granted Fast Track Designation for SGT-212 for the treatment of FA. The FDA and the European Medicines Agency, or EMA, have granted orphan drug designation to SGT-501 for the treatment of CPVT and the FDA has granted Rare Pediatric Disease Designation for SGT-501.

SGT-003

Patient dosing in the Phase 1/2 INSPIRE DUCHENNE trial of SGT-003 began in the second quarter of 2024. The INSPIRE DUCHENNE trial is a Phase 1/2 first-in-human, open-label, single-dose, multicenter trial designed to evaluate the safety, tolerability and efficacy of SGT-003 in pediatric patients with Duchenne at a dose of 1E14vg/kg. SGT-003 is administered as a one-time intravenous infusion. In September 2024, we amended the INSPIRE DUCHENNE clinical trial protocol to increase the anticipated participant enrollment size, expand the participant cohort age groups, and extend the timepoints of certain secondary objective measurements. In connection with the expanded clinical trial, we have initiated work for additional GMP batches of SGT-003.

On February 18, 2025, we announced positive initial data from the Phase 1/2 INSPIRE DUCHENNE trial as of the data cutoff date of February 11, 2025. Interim biopsy data reported in the first three participants showed an average microdystrophin expression of 110%, as measured by western blot, and improvements in multiple biomarkers that are indicators of muscle integrity, health and resilience.

SGT-003 was well-tolerated in the first six participants dosed as of February 11, 2025. For a full description of the initial results from the INSPIRE DUCHENNE trial, see Part I, Item I, “Business” appearing in this Annual Report on Form 10-K.

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Enrollment in the INSPIRE DUCHENNE trial is ongoing, with at least 10 total participants in the trial anticipated to be dosed by early in the second quarter of 2025 and approximately 20 total participants anticipated to be dosed by the fourth quarter of 2025.

INSPIRE DUCHENNE currently has a total of six active clinical sites in the United States and Canada and approved clinical trial applications in the United Kingdom and Italy. We expect to activate additional trial sites by the end of 2025. In mid-2025, we plan to request a meeting with the U.S. Food and Drug Administration, or the FDA, to discuss the potential for accelerated approval regulatory pathways for SGT-003.

SGT-212

In January 2025, we announced that the FDA cleared our investigational new drug, or IND, for SGT-212 for the treatment of FA. We anticipate initiating an open-label, multi-center Phase 1b clinical trial of SGT-212 in non-ambulatory and ambulatory adult patients living with FA in the second half of 2025. The FDA has granted Fast Track designation to SGT-212 for the treatment of FA.

SGT-501

We have conducted preclinical studies of SGT-501, including three-and six-month good laboratory practices, or GLP, toxicology studies. IND-enabling GLP toxicology studies of SGT-501 in non-human primates, including the in-life portion of the six-month toxicology, were completed in the first quarter of 2025. We expect to submit an IND to the FDA for SGT-501 for the treatment of patients with RYR2-mediated CPVT in the first half of 2025.

Other Cardiac Programs

We are currently developing a preclinical stage product candidate, SGT-601, for the treatment of TNNT2 DCM. Efficacy studies in mice suggest that SGT-601 treatment resulted in a restoration of ejection fraction function and a stabilization in cardiac function over time. We anticipate submitting an IND to the FDA for SGT-601 for the treatment of TNNT2 DCM in the second half of 2026.

Capsid

Solid's proprietary capsid used in SGT-003, AAV-SLB101, was well tolerated in the first patients dosed in the INSPIRE DUCHENNE trial as well as in NHP and mouse studies.

We are focused on developing transformative treatments to improve the lives of patients with rare neuromuscular and cardiac diseases. The majority of our current programs are designed to treat these diseases with gene transfer products. Gene transfer, a type of gene therapy, is designed to address diseases caused by mutated genes through the delivery of functional versions of those genes, called transgenes. The transgenes are then utilized by the body to produce proteins that act therapeutically to treat the condition. In addition to a transgene, our gene transfer Candidates include a viral capsid or vector (a protein shell utilized as a vehicle to deliver a transgene to cells in the body) and a promoter (a specialized DNA sequence that directs cells to produce the protein in specific tissues). The capsid is modified to no longer self-replicate yet still retain its ability to introduce new genetic material directly into patients’ cells. Adeno-associated virus, or AAV, capsids have been approved for use to deliver transgenes to patients, including via systemic delivery as well as stereotactic neurosurgical administration to the brain. The use of AAV capsids to deliver gene therapies has also been extensively studied by third parties in human clinical trials for multiple disease indications, and in certain of these trials AAV was delivered systemically to the patient.

Our Operations

Due to our significant research and development expenditure, licensing and patent investment, and general and administrative costs associated with our operations, we have generated substantial operating losses in each period since our inception. Our net losses were $124.7 million and $96.0 million for the years ended December 31, 2024 and 2023, respectively. As of December 31, 2024, we had an accumulated deficit of $783.5 million. We expect to incur significant expenses and operating losses for the foreseeable future.

As we seek to develop and commercialize our Candidates, we anticipate that our expenses will increase significantly and that we will need substantial additional funding to support our continuing operations. Until such time as we can generate significant revenue from product sales, if ever, we expect to finance our operations through a combination of public or private equity financings, debt financings or other sources, which may include licensing agreements or strategic collaborations. We may be unable to raise additional funds or enter into such agreements or arrangements when needed on favorable terms, if at

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all. If we fail to raise capital or enter into such agreements as and when needed, we may have to significantly delay, scale back or discontinue the development or commercialization of our Candidates.

Because of the numerous risks and uncertainties associated with product development, we are unable to predict the timing or amount of increased expenses or determine when or if we will be able to achieve or maintain profitability. Even if we are able to generate revenue from product sales, we may not become profitable. If we fail to become profitable or are unable to sustain profitability on a continuing basis, we may be unable to continue our operations at planned levels and be forced to reduce or terminate our operations.

As of December 31, 2024, we had cash, cash equivalents, and available-for-sale securities of $148.9 million, excluding restricted cash of $2.0 million. In February 2025, we issued and sold in an underwritten offering, or the February 2025 Offering, 35,739,810 shares of our common stock at a price per share of $4.03, and, to certain investors in lieu of shares of common stock, pre-funded warrants to purchase 13,888,340 shares of our common stock at a price per warrant of $4.029. We received net proceeds of approximately $187.5 million, after deducting underwriting discounts and commissions and estimated offering costs. We believe that our cash, cash equivalents, and available-for-sale securities as of December 31, 2024, together with the net proceeds from the February 2025 Offering, will enable us to fund our operating expenses and capital expenditure requirements into the first half of 2027. We have based this estimate on assumptions that may prove to be wrong, and we could use our available capital resources sooner than we currently anticipate.

Financial Operations Overview

Revenue

We have not generated any commercial product revenue to date and do not expect to generate any product revenue from the sale of our products for the foreseeable future, if ever. If our development efforts for our Candidates are successful and result in marketing approval, we may generate commercial product revenue in the future from product sales.

Operating Expenses

We classify our operating expenses into two categories: research and development and general and administrative expenses. Personnel costs, including salaries, benefits, bonuses, and equity-based compensation expense comprise a significant component of both expense categories. We allocate expenses associated with personnel costs based on the nature of work associated with these resources.

Research and Development Expenses

Research and development expenses consist primarily of costs incurred for our research activities, including our discovery efforts, and clinical and preclinical development activities for our Candidates and include:

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expenses incurred under agreements with third parties, including contract research organizations, or CROs, that conduct research, preclinical and clinical activities on our behalf, as well as contract manufacturing organizations, or CMOs, that manufacture SGT-003, SGT-501, and other Candidates for use in our preclinical studies and clinical trials;

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salaries, benefits and other related costs, including equity-based compensation expense, for personnel engaged in research and development functions;

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costs of outside consultants, engaged to assist in our research and development activities, including their fees, equity-based compensation and related travel expenses;

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costs of laboratory supplies and acquiring, developing and manufacturing preclinical study and clinical trial materials;

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costs incurred in seeking regulatory approval of our Candidates;

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expenses incurred under our intellectual property licenses; and

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facility-related research and development expenses, which include direct depreciation costs and allocated expenses for rent and maintenance of facilities and other operating costs.

Research and development activities are central to our business model. We are still in the early stages of development of our Candidates. Candidates in later stages of clinical development generally have higher development costs than those in preclinical development or in earlier stages of clinical development, primarily due to the increased size and duration of later-stage clinical trials. We expect that our research and development expenses will continue to increase for the foreseeable

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future if and as we conduct clinical trials for SGT-003, initiate clinical trials for our other Candidates, including our planned Phase 1b clinical trial of SGT-212, and continue to identify and develop additional Candidates.

We typically use our employee and infrastructure resources across our Candidates. We track outsourced development costs and milestone payments made under our licensing arrangements by Candidate, but we do not allocate personnel costs, license payments made under our licensing arrangements or other internal costs to Candidates on a program-specific basis. These costs are included in unallocated research and development expenses in the table below.

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

Year Ended December 31,

Allocated research and development expenses:

Total allocated research and development expenses 52,122 34,927

Unallocated research and development expenses:

Total unallocated research and development expenses 44,309 41,636

Total research and development expenses $ 96,431 $ 76,563

We cannot determine with certainty the duration, costs, and timing of clinical trials of ongoing and planned SGT-003, SGT-212, SGT-501, or our other Candidates, or if, when, or to what extent we will generate revenue from the commercialization and sale of any of our Candidates for which we obtain marketing approval or our other research and development expenses. We may never succeed in obtaining marketing approval for any of our Candidates. The duration, costs, and timing of clinical trials and development of our Candidates will depend on a variety of factors, including:

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the scope, rate of progress, expense, and results of any clinical trials of our Candidates and other research and development activities that we may conduct;

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the imposition of regulatory restrictions on clinical trials, including full and partial clinical holds and the time and activities required to lift any such holds;

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uncertainties in clinical trial design and patient enrollment or drop out or discontinuation rates;

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significant and changing government regulation and regulatory guidance;

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potential additional studies or clinical trials requested by regulatory agencies;

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the timing and receipt of any marketing approvals; and

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the expense of filing, prosecuting, defending and enforcing any patent claims and other intellectual property rights.

General and Administrative Expenses

General and administrative expenses consist primarily of salaries and other related costs, including equity-based compensation, for personnel in our executive, finance, business development and administrative functions. General and administrative expenses also include legal fees relating to patent and corporate matters, professional fees for accounting, auditing, tax and consulting services, insurance costs, travel expenses, and facility-related expenses.

We expect that our general and administrative expenses will increase in the future as we support our research and development activities and activities related to our INSPIRE DUCHENNE trial, our planned Phase 1b clinical trial of SGT-212, and any other planned or future clinical trials for and potential commercialization of our Candidates.

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Other Income, Net

Other income, net consists primarily of interest income. Interest income consists of income earned on our cash and cash equivalents, available-for-sale securities, and restricted cash.

Income Taxes

We account for income taxes using an asset and liability approach, which requires recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the consolidated financial statements but have not been reflected in taxable income. A valuation allowance is established to reduce deferred tax assets to their estimated realizable value.

We account 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.

Critical Accounting Policies and Use of Estimates

Our management’s discussion and analysis of financial condition and results of operations is based on our consolidated financial statements, which have been 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 assumptions that affect the reported amounts of assets and liabilities, costs and expenses and the disclosure of contingent assets and liabilities in our consolidated 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 materially from these estimates.

While our significant accounting policies are described in more detail in the notes to our consolidated financial statements appearing at the end of this Annual Report on Form 10-K, we believe that the following accounting policies are those most critical to the judgments and estimates used in the preparation of our consolidated financial statements and that involve a significant level of estimation uncertainty.

Accrued Research and Development Expenses

As part of the process of preparing our consolidated 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 personnel to identify services that have been performed on our behalf and estimating the level of service performed and the associated costs incurred for the services when we have not yet been invoiced or otherwise notified of the 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 advanced payments. We make estimates of our accrued expenses as of each balance sheet date in our consolidated financial statements based on facts and circumstances known to us at that time. Examples of estimated accrued research and development expenses include fees paid to:

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CROs in connection with performing research activities, clinical trials and preclinical studies on our behalf;

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vendors in connection with preclinical development and clinical activities;

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vendors related to product manufacturing and development and distribution of clinical and preclinical supplies; and

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third parties under our intellectual property licenses.

We base our expenses related to preclinical studies and clinical trials on our estimates of the services rendered and efforts expended pursuant to quotes and contracts with multiple CROs that 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

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services provided and result in a prepayment of the expense. In accruing 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 our estimate, we adjust the accrual or amount of prepaid expense accordingly. Although we do not expect our estimates to be materially different from amounts actually incurred, our understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and could result in us reporting amounts that are too high or too low in any particular period.

Equity-Based Compensation

We have equity plans under which we make equity awards to employees, directors and non-employees. We measure all stock options and other stock-based awards granted to employees, directors and non-employees based on the fair value on the date of the grant and recognize compensation expense of those awards, over the requisite service period, which is generally the vesting period of the respective award. Forfeitures are accounted for as they occur. We apply the straight-line method of expense recognition to all awards with only service-based vesting conditions. For performance-based restricted stock unit awards, which are subject to the achievement of performance milestones, the fair value is recognized as expense over the requisite service periods when the achievement of such performance milestones is determined to be probable. If a performance milestone is not determined to be probable or is not met, no equity-based compensation expense is recognized, and any previously recognized expense is reversed. For stock-based awards granted to non-employees, compensation expense is recognized over the period during which services are rendered by such non-employees until completed.

The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model. In the first quarter of 2024, we determined that we have adequate historical stock price data to utilize solely our stock for historical volatility purposes. The expected term of stock options with service-based vesting conditions and options granted to non-employees 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. We use a 0% expected dividend yield in our determination of fair value based on the fact that we have never paid cash dividends and do not expect to pay any cash dividends in the foreseeable future, if ever.

Derivative Liabilities

In connection with the asset purchase agreement with FA212 LLC, or FA212, certain development milestone payments to FA212 are payable in either cash, equity, or a combination of both, at our discretion. Such contingent payments were determined to be derivative liabilities.

Derivative liabilities are recorded at fair value based on the probability weighted present value of the estimated cash flows pursuant to the contractual terms of each agreement. The derivative liabilities are remeasured quarterly with changes in fair value recorded in change in fair value of derivative liabilities in the consolidated statements of operations.

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Results of Operations

Comparison of the Years Ended December 31, 2024 and 2023

The following table summarizes our results of operations for the years ended December 31, 2024 and 2023 (in thousands, except percentages):

Year Ended December 31,

Operating expenses:

Other income, net:

Change in fair value of derivative liabilities (4,750 ) — (4,750 ) (100.0 )%

Research and Development Expenses

The following table summarizes our research and development expenses by Candidate for the respective periods (in thousands, except percentages):

Year Ended December 31,

Allocated research and development expenses:

Unallocated research and development expenses:

Research and development expenses for the year ended December 31, 2024 were $96.4 million, compared to $76.6 million for the year ended December 31, 2023. The increase of $19.9 million in research and development expenses was primarily related to a $14.0 million increase in costs for SGT-501 from increased manufacturing and study related costs, a $4.6 million increase in costs for SGT-212 related to the entry into the asset purchase agreement with FA212, and a $6.7 million increase in license fees and research and consulting costs for other development programs, partially offset by a $5.7 million decrease in costs for SGT-003 related to manufacturing and study related costs.

General and Administrative Expenses

General and administrative expenses were $33.3 million for the year ended December 31, 2024, compared to $27.8 million for the year ended December 31, 2023. The increase of $5.5 million was primarily related to a $4.1 million increase in personnel costs and a $1.4 million increase in legal fees.

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Restructuring Expense

There was no restructuring expense during the year ended December 31, 2024, compared to $(0.1) million of restructuring expense for the year ended December 31, 2023. The restructuring expense was related to severance and other employee-related costs we recorded in the year ended December 31, 2022, in connection with a restructuring that occurred in December 2022. We paid $0.3 million and $3.7 million in severance and other employee-related costs during the years ended December 31, 2024 and 2023, respectively. See Note 16 to our consolidated financial statements appearing at the end of this Annual Report on Form 10-K.

Other Income, Net

Other income, net was $5.0 million and $8.2 million for the years ended December 31, 2024 and 2023, respectively. The decrease of $3.2 million was primarily related to a $4.8 million expense for a change in fair value of derivative liabilities, partially offset by a $1.9 million increase in interest income primarily related to available-for-sale securities included within our portfolio.

Liquidity and Capital Resources

Sources of Liquidity

To date, we have financed our operations primarily through the sale of redeemable preferred units and member units, the sale of securities in private placements and follow-on offerings, the sale of common stock in our initial public offering, and sales of common stock under our “at-the-market offering” sales agreement with Jefferies LLC, or Jefferies, or the ATM Sales Agreement. Through December 31, 2024, we raised an aggregate of $144.6 million of gross proceeds from our sales of preferred units prior to the completion of our initial public offering, and an aggregate of $668.9 million of net proceeds from the sale of our common stock through public offerings, including our IPO and follow-on public offering, private placements, the ATM Sales Agreement, and pursuant to the stock purchase agreements.

On March 13, 2019, we entered into the ATM Sales Agreement, which was amended and restated in March 2024, under which we may offer and sell, from time to time, shares of our common stock through Jefferies as sales agent. Any such sales being made by any method that is deemed an “at-the-market offering” as defined in Rule 415 promulgated under the Securities Act. We will pay Jefferies a commission of up to 3% of the gross proceeds of any sales of common stock pursuant to the ATM Sales Agreement. During the years ended December 31, 2024 and 2023, we sold 2,212,937 and 602,030 shares of common stock, respectively, pursuant to the ATM Sales Agreement resulting in net proceeds of $18.4 million and $3.0 million, respectively. During the three months ended December 31, 2024, we sold 1,004,650 shares pursuant to the ATM Sales Agreement resulting in net proceeds of $6.9 million.

On January 11, 2024, we issued and sold 16,973,103 shares of our common stock at a price per share of $5.53 and, to one investor in lieu of shares of common stock, pre-funded warrants to purchase 2,712,478 shares of common stock at a price of $5.529 per pre-funded warrant, in a private placement, which we refer to as the January 2024 Private Placement. We received $103.7 million of net proceeds from the January 2024 Private Placement after deducting offering costs.

As of December 31, 2024, we had cash, cash equivalents and available-for-sale securities of $148.9 million, excluding restricted cash of $2.0 million, and had no debt outstanding.

On February 19, 2025, we issued and sold in the February 2025 Offering 35,739,810 shares of our common stock at a price of $4.03 per share, and, to certain investors in lieu of shares of common stock, pre-funded warrants to purchase 13,888,340 shares of our common stock at a price of $4.029 per pre-funded warrant. We received approximately $187.5 million of net proceeds from the February 2025 Offering, after deducting underwriting discounts and commissions and estimated offering costs.

Summary of Cash Flows

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

Year Ended December 31,

Net cash used in operating activities $ (100,012 ) $ (94,180 )

Net cash (used in) provided by investing activities (16,086 ) 9,689

Net cash provided by financing activities 122,437 3,122

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Operating Activities

During the year ended December 31, 2024,operating activities used $100.0 million of cash, primarily resulting from our net loss of $124.7 million offset by non-cash charges of $21.8 million due primarily to equity-based compensation of $10.5 million, an increase in the fair value of the derivative liabilities of $4.8 million, non-cash acquired in-process research and development of $3.4 million, depreciation expense of $2.5 million, non-cash lease expense of $2.4 million, and a non-cash up-front equity payment for a collaboration and license agreement of $2.0 million, partially offset by amortization of discount on available-for sale-securities of $3.6 million. Net cash provided by changes in our operating assets and liabilities was $2.9 million which included an increase of $4.8 million in accrued expenses and other current and non-current liabilities, and an increase in accounts payable of $2.2 million, partially offset by an increase in prepaid expenses and other current and non-current assets of $2.4 million and a decrease in operating lease liability of $1.7 million.

During the year ended December 31, 2023,operating activities used $94.2 million of cash, primarily resulting from our net loss of $96.0 million offset by non-cash charges of $10.7 million due primarily to equity-based compensation of $7.6 million and depreciation and impairment expense of $2.6 million, non-cash lease expense of $2.5 million, partially offset by amortization of discount on available-for sale-securities of $2.4 million. Net cash used by changes in our operating assets and liabilities was $8.9 million which included a decrease of $6.9 million in accrued expenses and other current and non-current liabilities, a decrease in operating lease liability of $1.7 million, and a decrease in accounts payable of $0.8 million, partially offset by a decrease in prepaid expenses and other current and non-current assets of $0.6 million.

Investing Activities

During the year ended December 31, 2024, investing activities used $16.1 million of cash, resulting from the purchases of available-for sale securities of $204.3 million and the purchases of property and equipment of $0.7 million, partially offset by the maturity of available-for sale securities of $188.9 million.

During the year ended December 31, 2023, investing activities provided cash of $9.7 million, consisting primarily of the sale of available-for-sale securities of $128.6 million, partially offset by net purchases of available-for-sale securities of $117.4 million and the purchase of property and equipment of $1.5 million primarily related to the corporate headquarters lease.

Financing Activities

During the year ended December 31, 2024, financing activities provided $122.4 million of cash, primarily resulting from the net proceeds from the sale of common stock and pre-funded warrants to purchase shares of common stock in the January 2024 Private Placement of $103.7 million and net proceeds from the sale of common stock under the ATM Sales Agreement of $18.4 million, proceeds from the exercise of common stock options of $0.5 million, and proceeds from the issuance of shares under the Company's Amended and Restated 2021 Employee Stock Purchase Plan, or ESPP, of $0.3 million, partially offset by payments of the principal portion of finance lease obligations of $0.5 million.

During the year ended December 31, 2023, financing activities provided $3.1 million of cash as a result of proceeds from the issuance of common stock of $3.0 million under the ATM Sales Agreement and from the issuance of shares of common stock of $0.1 million under the ESPP.

Funding Requirements

We expect our expenses to increase substantially in connection with our ongoing development activities related to our Candidates. In addition, we have incurred and expect to continue to incur costs associated with operating as a public company. We expect that our expenses will increase substantially if and as we:

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continue to enroll patients in our INSPIRE DUCHENNE trial and advance clinical development of SGT-003;

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advance our other Candidates into clinical trials, including our planned Phase 1b clinical trial of SGT-212;

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continue research and preclinical development of our Candidates and adjacent technologies such as assays;

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seek to identify additional candidates;

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engage in regulatory interactions with the FDA and other regulatory authorities;

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submit regulatory filings relating to the development of our Candidates and seek marketing approvals for our Candidates that successfully complete clinical trials, if any;

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

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scale up our manufacturing processes and arrange manufacturing for larger quantities of our product candidates for preclinical and clinical development and potential commercialization;

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

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hire and retain additional clinical, quality control and scientific personnel;

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build out new facilities or expand existing facilities to support our activities;

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acquire or in-license other drugs, drug candidates, technologies and intellectual property; and

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add operational, financial and management information systems and personnel.

As of December 31, 2024, we had cash, cash equivalents and available-for-sale securities of $148.9 million, excluding restricted cash of $2.0 million. Based on our current operating plan, we believe that our cash, cash equivalents and available-for-sale securities as of December 31, 2024, together with the net proceeds from our February 2025 Offering, will be sufficient to fund our operating expenses and capital requirements into the first half of 2027. As a result, in order to continue to operate our business beyond that time, we will need to raise additional funds. However, there can be no assurance that we will be able to generate funds on terms acceptable to us, on a timely basis, or at all. In addition, we have based this estimate on assumptions that may prove to be wrong, and we could use our available capital resources sooner than we currently anticipate.

Due to the numerous risks and uncertainties associated with the development of our Candidates and because the extent to which we may enter collaborations with third parties for development of our Candidates is unknown, we are unable to estimate the timing and amounts of increased capital outlays and operating expenses associated with completing the research and development of our Candidates. Our future capital requirements will depend on many factors, including:

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the progress, costs and results of the INSPIRE DUCHENNE trial, our planned clinical trial of SGT-212, and any future clinical trials of our Candidates;

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the costs, timing and outcome of regulatory review of our Candidates;

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the scope, progress, results and costs of discovery, laboratory testing, manufacturing, preclinical development and clinical trials for our Candidates;

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the costs associated with manufacturing and use of third-party manufacturers;

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the revenue, if any, received from commercial sale of our Candidates, should any of our Candidates receive marketing approval;

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the costs of preparing, filing and prosecuting patent applications, maintaining, defending and enforcing our intellectual property rights and defending intellectual property-related claims;

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the outcome of any lawsuits filed against us;

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the terms of our current and any future license agreements and collaborations;

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our ability to establish and maintain additional strategic collaborations, licensing or other arrangements and the financial terms of such arrangements;

•

the payment or receipt of milestones, royalties and other collaboration-based revenues, if any;

•

the extent to which we acquire or in-license other candidates, technologies and intellectual property; and

•

if and as we need to adapt our business in response to public health emergencies or pandemics and collateral consequences related thereto.

We are supplying, and expect to continue to supply, our ongoing and future pre-clinical and clinical development programs with drug produced at a cGMP compliant facility located at one of our CMOs. We intend to establish the capability and capacity to supply Candidates at commercial scale from multiple sources.

Developing pharmaceutical products, including conducting preclinical studies and clinical trials, is a time-consuming, expensive and uncertain process that takes years to complete, and we may never generate the necessary data or results required to obtain marketing approval for any Candidates or generate revenue from the sale of any products for which we

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may obtain marketing approval. In addition, our Candidates, if approved, may not achieve commercial success. Our commercial revenues, if any, will be derived from sales of products that we do not expect to be commercially available for many years, if ever. Accordingly, we will need to obtain substantial additional funds to achieve our business objectives.

Adequate additional funds may not be available to us on acceptable terms, or at all. We do not currently have any committed external source of funds. To the extent that we raise additional capital through the sale of equity securities, our existing stockholders’ ownership interest may be diluted. Any debt or preferred equity financing, if available, may involve agreements that include restrictive covenants that may limit our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends, which could adversely impact our ability to conduct our business, and may require the issuance of warrants, which could potentially dilute existing stockholders’ ownership interests.

If we raise additional funds through licensing agreements and strategic collaborations with third parties, we may have to relinquish valuable rights to our technology, future revenue streams, research programs, or Candidates or grant licenses on terms that may not be favorable to us. If we are unable to raise additional funds, we may be required to delay, limit, reduce and/or terminate development of our Candidates or any future commercialization efforts or grant rights to develop and market Candidates that we would otherwise prefer to develop and market ourselves.

Contractual Obligations and Commitments

We lease certain office space, lab space and lab equipment in Massachusetts and North Carolina. These leases are used for our continuing operations. For a description of our lease obligations, refer to Note 10 to our consolidated financial statements appearing in this Annual Report on Form 10-K.

Under various agreements with third-party licensors, we have agreed to make milestone payments and pay royalties to third parties based on specified milestones. For a description of our license agreements, see Part I, Item 1, “Business—Strategic Partnerships and Collaborations/Licenses” and see Note 12 of our consolidated financial statements appearing in this Annual Report on Form 10-K.

We enter into contracts in the normal course of business with CROs and CMOs for clinical trials, preclinical research studies and testing, manufacturing and other services and products for operating purposes. These contracts are cancelable by us upon prior notice of 30 days.

Recently Issued Accounting Pronouncements

We have reviewed all recently issued standards and have determined that, other than as disclosed in Note 2 to our consolidated financial statements appearing at the end of this Annual Report on Form 10-K, such standards will not have a material impact on our consolidated financial statements or do not otherwise apply to our operations.

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

Interest Rate Risk

We are exposed to market risk related to changes in interest rates. As of December 31, 2024, our cash equivalents consisted of money market accounts and treasury bills that have contractual maturities of less than 90 days from the date of acquisition. As of December 31, 2024, our investments consisted of treasury bills and government bonds that have contractual maturities of less than one year. Our primary exposure to market risk is interest income sensitivity, which is affected by changes in the general level of U.S. interest rates. However, because of the short-term nature of our portfolio, an immediate 10% change in market interest rates would not have a material impact on the fair market value of our investment portfolio or on our financial position or results of operations.

Inflation Risk

Inflation generally affects us by increasing our cost of labor and research, manufacturing and development costs. We do not believe that inflation had a material effect on our business, financial condition or results of operations in the last two years. However, our operations may be adversely affected by the inflation in the future.

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Item 8. Financial Statements and Supplementary Data.

The information required by this Item 8 is included at the end of this Annual Report on Form 10-K beginning on page F-1.

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

Not applicable.

Item 9A. Controls and Procedures.

Evaluation of Disclosure Controls and Procedures

Our management, with the participation of our Chief Executive Officer and Chief Financial Officer (our principal executive officer and principal financial and accounting officer, respectively), evaluated the effectiveness of our disclosure controls and procedures as of December 31, 2024. The term "disclosure controls and procedures," as defined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as amended, or the Exchange Act, refers to controls and other procedures of a company that are designed to ensure that information required to be disclosed by a company in the reports that it files or submits under the Exchange 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 such information required to be disclosed by a company in the reports that it files or submits under the Exchange Act is accumulated and communicated to a company's management, including its principal executive and principal financial and accounting officers, or persons performing similar functions, as appropriate to allow timely decisions regarding required disclosure.

In designing and evaluating our disclosure controls and procedures, management recognizes that disclosure controls and procedures, no matter how well designed and operated, can provide only reasonable, not absolute, assurance that the objectives of the disclosure controls and procedures are met. Additionally, in designing disclosure controls and procedures, our management necessarily was required to apply its judgment in evaluating the cost-benefit relationship of possible disclosure controls and procedures. The design of any system of controls also is based in part upon certain assumptions about the likelihood of future events, and there can be no assurance that any design will succeed in achieving its stated goals under all potential future conditions; over time, controls may become inadequate because of changes in conditions, or the degree of compliance with policies or procedures may deteriorate. Because of the inherent limitations in a control system, misstatements due to error or fraud may occur and not be detected.

Based on the evaluation of our disclosure controls and procedures, our Chief Executive Officer and Chief Financial Officer concluded that, as of December 31, 2024, our disclosure controls and procedures were designed and operating effectively.

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 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. 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.

Management conducted an evaluation of the effectiveness of our internal control over financial reporting as of December 31, 2024 based on the framework in Internal Control-Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission. Based on that evaluation, management has concluded that the Company's internal control over financial reporting was effective as of December 31, 2024.

As a non-accelerated filer and a “smaller reporting company”, as defined in Rule 12b-2 under the Exchange Act, our independent registered public accounting firm is not required to issue an attestation report on our internal control over financial reporting.

Changes in Internal Control over Financial Reporting

There have been no changes in our internal control over financial reporting (as defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act) that occurred during the three months ended December 31, 2024 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

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Item 9B. Other Information.

(b) Director and Officer Trading Arrangements

None of our directors or officers 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 2024.

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

Not applicable.

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PART III

Item 10. Directors, Executive Officers and Corporate Governance.

Set forth below are the names, ages and positions of our current executive officers and directors as of March 6, 2025.

Name Age Position(s) held

Executive Officers

Alexander Cumbo 54 President, Chief Executive Officer and Director

Gabriel Brooks, M.D. 48 Chief Medical Officer

Jessie Hanrahan, Ph.D. 49 Chief Regulatory Officer

Paul Herzich 47 Chief Technology Officer

David Tyronne Howton 53 Chief Operating Officer and Secretary

Kevin Tan 47 Chief Financial Officer and Treasurer

Non-Employee Directors

Ian F. Smith 59 Executive Chairman of the Board

Martin Freed, M.D. 64 Director

Ilan Ganot 51 Director

Clare Kahn, Ph.D. 73 Director

Georgia Keresty, Ph.D. 63 Director

Sukumar Nagendran, M.D. 59 Director

Adam Stone 45 Director

Lynne Sullivan 58 Director

Executive Officers

Alexander Cumbo has served as our President and Chief Executive Officer and as a director since December 2022. Prior to that, Mr. Cumbo served as the President and Chief Executive Officer and as a director of AavantiBio, a gene therapy company, from October 2020 to December 2022, when we acquired AavantiBio. From January 2013 to October 2020, Mr. Cumbo held positions of increasing responsibility at Sarepta Therapeutics, Inc., or Sarepta, a precision genetic medicine company, ultimately serving as Executive Vice President, Chief Commercial Officer. From 2011 to 2013, Mr. Cumbo served as Vice President of Sales and Treatment Education for Vertex Pharmaceuticals Incorporated, or Vertex, a biotechnology company, launching Incivek, a treatment for hepatitis C, and from 2010 to 2011, he served as area director for Vertex. Prior to Vertex, Mr. Cumbo served in multiple commercial roles supporting the HIV, HBV and cardiovascular franchises at Gilead Sciences, Inc., a biopharmaceutical company. Mr. Cumbo has served on the Board of Directors of Verve Therapeutics, Inc. since June 2022. Mr. Cumbo previously served on the Board of Directors of RA Pharmaceuticals, Inc., a clinical stage biopharmaceutical company acquired by UCB, Brussels, from November 2018 to April 2020. Mr. Cumbo received a Bachelor of Science in Laboratory Technology from Auburn University. Mr. Cumbo is qualified to serve on our Board of Directors based on his extensive and broad range of experience in the biopharmaceutical industry and his deep knowledge of our company as our Chief Executive Officer.

Gabriel Brooks, M.D. has served as our Chief Medical Officer since October 2023. Prior to that, Dr. Brooks served as Executive Director of Pfizer Inc., or Pfizer, a pharmaceutical company, from September 2020 to October 2023. Prior to joining Pfizer, Dr. Brooks served as Vice President of Research and Development for 4D Molecular Therapeutics, Inc., a biopharmaceutical company, from November 2018 to September 2020. Prior to joining 4D Molecular Therapeutics, Inc., Dr. Brooks served as Medical Director for GE HealthCare Technologies Inc., or GE Healthcare, a medical technology company. Prior to joining GE HealthCare, Dr. Brooks served as Associate Director of Clinical Research at Gilead Life Sciences, Inc., a biopharmaceutical company, from August 2015 to April 2017. Dr. Brooks received a Bachelor of Science in Biology from Carnegie Mellon University, a Doctor of Medicine from Cornell University, and a Master of Applied Sciences of Biostatistics and Epidemiology from the University of California, San Francisco. He completed his training in Internal Medicine at Johns Hopkins Hospital, Baltimore, and fellowships in general Cardiology and Advanced Imaging at the University of California, San Francisco.

Jessie Hanrahan, Ph.D. has served as our Chief Regulatory Officer since December 2022. Prior to that, Dr. Hanrahan served as Chief Regulatory Officer of AavantiBio from May 2021 to December 2022. Prior to joining AavantiBio, Dr. Hanrahan served as the Vice President of Regulatory Science at bluebird bio, Inc., or bluebird, a biotechnology company, from February 2020 to May 2021 and Senior Director of Regulatory Science at bluebird from August 2016 to February 2020. Prior to joining bluebird, Dr. Hanrahan worked at Sanofi Genzyme, a biotechnology company, as Senior Manager of Regulatory Affairs from October 2009 to July 2016 and as Principal Medical Writer from July 2007 to October 2009. Prior to joining Sanofi Genzyme, Dr. Hanrahan served as a Medical Writer at Boston Scientific, a biomedical engineering firm, from May

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2006 to July 2007. Dr. Hanrahan holds a Ph.D., M.S. and M.Ph. in Molecular, Cellular and Developmental Biology from Yale University. Dr. Hanrahan received a Bachelor of Arts in Biology and History from Mount Holyoke College.

Paul Herzich has served as our Chief Technology Officer since December 2022. Prior to that, Mr. Herzich served as Chief Technology Officer of AavantiBio from April 2021 to December 2022. Before joining AavantiBio, Mr. Herzich served as Vice President of CMC at BridgeBio Pharma, Inc., or BridgeBio, a biopharmaceutical company, from August 2020 to April 2021. Previously, Mr. Herzich served as Head of Manufacturing Operations at BridgeBio from July 2019 to July 2020. Before joining BridgeBio, Mr. Herzich served as Senior Director of Manufacturing at LogicBio Therapeutics, Inc., a genetic medicine company, from January 2018 to July 2019. Additionally, Mr. Herzich served as Senior Manager and Director of cGMP Gene Therapy Manufacturing at Pfizer from August 2016 to January 2018. From July 2015 to August 2016, Mr. Herzich served as the head of TD Manufacturing at CSL Seqirus, a pharmaceutical company, after its acquisition of Novartis Vaccines and Diagnostics, Inc., where Mr. Herzich served in various roles of increasing responsibility from December 2007 to July 2015. Mr. Herzich holds a Master of Business Administration from North Carolina State University Poole College of Management and a Bachelor of Science in Biology from Rutgers University.

David Tyronne Howton has served as our Chief Operating Officer since September 2023 and as our Secretary since December 2022. Mr. Howton previously served as our Chief Administrative Officer from December 2022 to September 2023 and as our General Counsel from December 2022 to July 2024. Prior to that, Mr. Howton served as the Chief Operating Officer and General Counsel of AavantiBio from March 2021 to December 2022. From November 2012 to December 2020, Mr. Howton served as Executive Vice President, General Counsel and Corporate Secretary at Sarepta. Prior to joining Sarepta, Mr. Howton served as the Senior Vice President and Chief Legal Officer and Chief Compliance Officer at Vertex. Prior to Vertex, Mr. Howton served in multiple legal roles at Genentech, Inc., a biotechnology company. Mr. Howton has served on the board of Make-A-Wish® Massachusetts and Rhode Island since March 2021. Mr. Howton received a Bachelor of Arts in Political Science from Yale University and a Juris Doctor from Northwestern University School of Law.

Kevin Tan has served as our Chief Financial Officer and Treasurer since January 2023. Prior to that, Mr. Tan served as the Chief Financial Officer at Selecta Biosciences, Inc., or Selecta, a biopharmaceutical company, from September 2021 to November 2022. Prior to joining Selecta, Mr. Tan served as Treasurer at Sarepta from July 2020 to September 2021. Prior to becoming Treasurer at Sarepta, he served as Assistant Treasurer from May 2018 to June 2020. Before joining Sarepta, Mr. Tan worked as a freelance consultant from February 2017 to April 2018, providing independent financial advice and advisory services to individuals and private companies. From June 2012 to November 2016, Mr. Tan served as Senior Portfolio Manager — Public Market Investments at CPP Investments (f/k/a the Canada Pension Plan Investment Board). He has also served in various positions at Macquarie Capital (USA) Inc., Arrowhawk Capital Partners LLC, Lehman Brothers Inc. (subsequently acquired by Barclays Capital Inc.) and UBS Investment Bank. Mr. Tan holds a Bachelor of Commerce degree from Queen's University at Kingston, a Master of Engineering degree from The Graduate School at Princeton University, and a Master of Business Administration degree from the University of Chicago Booth School of Business. Mr. Tan is a Chartered Financial Analyst (CFA) charterholder.

Non-Employee Directors

Ian F. Smith is Executive Chairman of our Board of Directors and has served as a member of our Board of Directors since April 2020 and served as a consultant to us from February 2020 to December 2021. Mr. Smith is also the chairman of the Board of Directors of Rivus Pharmaceuticals, Inc. and iVexSol, Inc, and a member of the Board of Directors of Stoke Therapeutics, Inc., Foghorn Therapeutics Inc., Odyssey Therapeutics, Inc. and Alkeus Pharmaceuticals, Inc., which are all biotechnology companies. He is also a Senior Advisor to Bain Capital Life Sciences. Between 2001 and 2019, Mr. Smith served as Chief Financial Officer and then Chief Operating Officer at Vertex. He received a B.A. with honors in accounting and finance from Manchester Metropolitan University (UK). Mr. Smith is qualified to serve on our Board of Directors because of his more than 25 years of finance and broad operating experience for public companies in the biopharmaceutical industry.

Martin Freed, M.D., F.A.C.P. has served as a member of our Board of Directors since June 2018. Dr. Freed has served as an independent consultant to several private pharmaceutical, biotechnology, and healthcare companies, specializing in clinical and general pharmaceutical development and clinical and regulatory strategy since February 2015. He co-founded and served as Chief Medical Officer of Civitas Therapeutics, Inc., a biopharmaceutical company acquired by Acorda Therapeutics, Inc., from December 2010 to October 2014, and as Senior Vice President, Clinical Development of Acorda Therapeutics, Inc. from October 2014 to January 2015. He has also served as Chief Medical Officer at Adnexus Therapeutics, Inc. (acquired by Bristol-Myers Squibb) and Vitae Pharmaceuticals, Inc. Dr. Freed spent nearly 14 years at GlaxoSmithKline and its predecessor, SmithKline Beecham Pharmaceuticals or SmithKline Beecham, where he served numerous roles including vice president, clinical development and medical affairs in the metabolism therapeutic area. Dr. Freed currently serves on the Board of Directors for Avilar Therapeutics, Inc. He previously served on the Board of Directors for Sojournix, Inc., Dicerna

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Pharmaceuticals and Intekrin Therapeutics. Dr. Freed has been Board Certified in Internal Medicine, Nephrology and Clinical Pharmacology. He performed his internal medicine residency at Temple University Hospital and nephrology fellowship at Yale-New Haven Hospital. A Fellow of the American College of Physicians, Dr. Freed received a B.S. with distinction in biology from the University of Delaware and an M.D. from Pennsylvania State University's College of Medicine. Dr. Freed is qualified to serve on our Board of Directors because of his extensive leadership experience, his public company board experience and his experience working in the healthcare sector.

Ilan Ganot is one of our founders and has served as a member of our Board of Directors since our inception in 2013. He also served as our Chief Executive Officer from 2013 to December 2022 and as our President from June 2018 to December 2022. From December 2022 to December 2023, Mr. Ganot assisted with the transition of his duties to Mr. Cumbo and provided other consulting and advisory services, as requested from time to time by us. Mr. Ganot is currently the Chief Executive Officer and a member of the Board of Alesta Therapeutics, a biotechnology company focused on the development of innovative therapies for rare diseases. Mr. Ganot is also a member of the Board of Directors of Minovia Therapeutics, a biotechnology company. Previously, Mr. Ganot served as an investment banker at JPMorgan Chase & Co., Nomura Securities Co., Ltd., and Lehman Brothers. Mr. Ganot received his MBA from London Business School and holds law and business degrees from Reichman University in Herzliya, Israel. Mr. Ganot also practiced corporate law in Israel and was a Captain in the Israeli Defense Forces. He is qualified to serve on our Board of Directors because of his personal dedication to improving treatments available for Duchenne patients, his extensive leadership experience and his extensive knowledge of our company based on his previous role as our Chief Executive Officer.

Clare Kahn, Ph.D. has served as a member of our Board of Directors since March 2021 and has served as a consultant to us since June 2022. Dr. Kahn has served as R&D Strategy Officer at X-VAX Technology Inc., or X-VAX, a biotechnology company developing vaccines against pathogens acquired by mucosal infection such as herpes, since September 2019. She served as Chief Regulatory and Preclinical Development Officer at X-VAX from September 2018 to September 2019. Dr. Kahn has also been the president of Clare Kahn Pharma Consulting LLC, through which she provides consulting services on regulatory strategy since July 2016. Dr. Kahn was previously Vice President, Worldwide Regulatory Strategy, Global Innovative Pharma at Pfizer from January 2014 to June 2016 and Vice President, Worldwide Regulatory Strategy, Specialty Care Business at Pfizer from June 2010 to December 2013. Prior to Pfizer, she was Vice President of Regulatory Affairs for a variety of therapeutic areas including cardiovascular, metabolic, urology, oncology and vaccines at GlaxoSmithKline from 1999 to 2010. Dr. Kahn has a Ph.D. in Biochemical Pharmacology from The Royal Postgraduate Medical School, London and served as Assistant Professor of Pharmacology and of Pathology and Laboratory Medicine at The University of Pennsylvania from 1981 to 1985. Dr. Kahn is qualified to serve on our Board of Directors because of her extensive leadership experience and her experience working in the healthcare sector.

Georgia Keresty, Ph.D., M.PH. has served as a member of our Board of Directors since March 2021. Dr. Keresty served as the Chief Operating Officer at Volnay Therapeutics, a biotechnology start-up company, from March 2023 to November 2024. Prior to this role, Dr. Keresty served as a senior advisor to Takeda R&D in 2021 and was their R&D Chief Operating Officer from 2017 to 2020. From 2003 to 2017 and from 1997 to 1999, she was an executive at Johnson & Johnson. From 1999 to 2003 and from 1983 to 1997, she held roles at Bristol-Myers Squibb Company and Novartis Pharmaceuticals Corporation or Novartis, respectively. Dr. Keresty holds BSc degrees in Chemical Engineering and Computer Science from Clarkson University and Ramapo College of New Jersey, an M.S. degree in Information Systems from Pace University, an MBA in Operations Management from Rutgers University, a Ph.D. in Operations Management from Rutgers University, and an MPH in Global Health Leadership from the University of Southern California. Dr. Keresty currently serves on the Board of Directors of Intellia Therapeutics, Inc. Dr. Keresty previously served on the Board of Directors of Aspen Technology, Inc. and Commissioning Agents, Inc. Dr. Keresty is also an NACD Board Leadership Fellow and Directorship Certified® since September 2020 and earned an NACD CERT Certificate in Cyber-Risk Oversight in January 2024. Dr. Keresty is qualified to serve on our Board of Directors because of her extensive leadership and governance experience, and her experience working in the healthcare sector.

Sukumar Nagendran, M.D. has served as a member of our Board of Directors since September 2018. Since December 2022, Dr. Nagendran has served as President, Head of Research and Development at Taysha Gene Therapies, Inc., a gene therapy company, and he has served as a member of their Board of Directors since July 2020. Prior to that, he was the Chief Medical Officer and President of Research and Development at Jaguar Gene Therapy, or Jaguar, a biotechnology company, from February 2020 to December 2022. Prior to Jaguar, Dr. Nagendran was Chief Medical Officer and Senior Vice President of AveXis Inc., or AveXis, a clinical-stage gene therapy company, from September 2015 to July 2018, prior to the company's acquisition by Novartis. Prior to AveXis, Dr. Nagendran was Vice President of Medical Affairs of Quest Diagnostics, a provider of diagnostic information services, from March 2013 to September 2015. Prior to Quest Diagnostics, Dr. Nagendran held key leadership positions at Pfizer, Novartis, Daiichi Sankyo, and Reata Pharmaceuticals. Prior to moving to the biotech industry, Dr. Nagendran practiced internal medicine, with a focus on diabetes and cardiovascular disease. He is a Mayo Alumni Laureate and founding member of the Robert Wood Johnson Legacy Society. He is also the sponsor for the

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Fonseca-Nagendran Scholar award at the American Diabetes Association to enhance research in minority populations. Dr. Nagendran currently serves on the Board of Directors of SalioGen Therapeutics. Dr. Nagendran received his undergraduate degree in Biochemistry from Rutgers University and his M.D. from Rutgers Medical School and trained in Internal Medicine at Mayo Clinic, Rochester. Dr. Nagendran is qualified to serve on our Board of Directors because of his extensive leadership experience and his experience working in the healthcare sector

Adam Stone has served as a member of our Board of Directors since November 2015. Mr. Stone is currently the Chief Investment Officer of Perceptive Advisors, a life sciences focused investing firm, where he has worked since 2006. Since July 2021 and February 2021, respectively, Mr. Stone has served as a director and Chief Executive Officer of ARYA Sciences Acquisition Corp V and ARYA Sciences Acquisition Corp IV. Mr. Stone is currently a member of the Board of Directors of Immatics N.V., a public biopharmaceutical company, and LianBio and Xontogency LLC, both private companies, and he previously served as a member of the Board of Directors of Renovia Inc. and Prometheus Biosciences, Inc. Mr. Stone received a B.A. in molecular biology from Princeton University. Mr. Stone is qualified to serve on our Board of Directors because of his extensive experience developing early-stage biotech and healthcare companies.

Lynne Sullivan has served as a member of our Board of Directors since November 2015. Ms. Sullivan has served as the Chief Financial Officer for UNITY Biotechnology, Inc., a biotechnology company, since August 2020. Prior to that, Ms. Sullivan served as the Chief Financial Officer for Compass Therapeutics, LLC, or Compass, a biotechnology company, from December 2018 to August 2019. Prior to Compass, Ms. Sullivan served as Biogen Inc.'s senior vice president of Finance from 2016 to December 2018, where she also served as vice president of Tax and Corporate Finance from February 2015 to March 2016 and vice president of Tax from April 2008 to February 2015. Ms. Sullivan is currently a member of the Board of Directors of Inozyme Pharma, Inc., a public biopharmaceutical company. She previously served as a member of the Board of Directors of BiomX Inc. She received an M.S. in Taxation from Bentley University and a B.S.B.A. from Suffolk University. Ms. Sullivan was a Certified Public Accountant for over 20 years. Ms. Sullivan is qualified to serve on our Board of Directors because of her extensive experience in public accounting and financial expertise and her experience working in the healthcare sector.

Composition of the Board of Directors

Our board of directors currently consists of nine members divided into three classes, with members of each class holding office for staggered three-year terms. There are currently two Class I directors (Alexander Cumbo and Sukumar Nagendran), whose terms expire at the 2025 annual meeting of stockholders; three Class II directors (Clare Kahn, Adam Stone and Lynne Sullivan), whose terms expire at the 2026 annual meeting of stockholders; and four Class III directors (Martin Freed, Ilan Ganot, Georgia Keresty and Ian Smith) whose terms expire at the 2027 annual meeting of stockholders (in all cases subject to the election and qualification of their successors or to their earlier death, resignation or removal).

Delinquent Section 16(a) Reports

Section 16(a) of the Exchange Act requires our directors and executive officers and holders of more than 10% of our common stock to file with the SEC initial reports of ownership and reports of changes in ownership of our common stock and other equity securities.

Based solely on a review of our records and representations made by the persons required to file these reports, we believe all directors, executive officers, and 10% owners timely filed all reports regarding transactions in our securities required to be filed by Section 16(a) under the Exchange Act for the fiscal year ended December 31, 2024, with the exception of a Form 4 filed by Adam Stone on November 19, 2024 to report the grant of stock options on June 11, 2024.

Audit Committee

The members of our audit committee are Ms. Sullivan, Dr. Keresty and Mr. Stone, with Ms. Sullivan serving as chair of the audit committee. Our Board of Directors has determined that each of these individuals meets the independence requirements of the Sarbanes-Oxley Act, Rule 10A-3 under the Exchange Act, and the applicable listing standards of Nasdaq. Each member of our audit committee can read and understand fundamental financial statements in accordance with Nasdaq audit committee requirements. In arriving at this determination, the Board of Directors has examined each audit committee member’s employment and other experience. Our Board of Directors has determined that Ms. Sullivan qualifies as an audit committee financial expert within the meaning of SEC regulations and meets the financial sophistication requirements of the Nasdaq listing rules. In making this determination, our Board of Directors has considered Ms. Sullivan’s formal education and previous and current experience in financial roles. Both our independent registered public accounting firm and management periodically meet privately with our audit committee. Our audit committee met four times during fiscal year 2024.

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Our audit committee’s responsibilities include, among other things:

•

appointing, approving the compensation of, and assessing the independence of our registered public accounting firm;

•

overseeing the work of our independent registered public accounting firm, including through the receipt and consideration of reports from that firm;

•

reviewing and discussing with management and our independent registered public accounting firm our annual and quarterly financial statements and related disclosures;

•

monitoring our internal control over financial reporting, disclosure controls and procedures and Code of Conduct;

•

overseeing our risk assessment and risk management policies;

•

overseeing cybersecurity risks;

•

establishing procedures for the receipt and retention of accounting related complaints and concerns;

•

meeting independently with our internal auditing staff, if any, our independent registered public accounting firm and management;

•

reviewing and approving or ratifying any related person transactions;

•

reviewing on a periodic basis our investment policy; and

•

preparing the audit committee report required by SEC rules.

We believe that the composition and functioning of our audit committee complies with all applicable requirements of the Sarbanes-Oxley Act and all applicable SEC and Nasdaq rules and regulations.

Code of Conduct

We have adopted a Code of Business Conduct and Ethics, or the Code of Conduct, that applies to our directors, executive officers and employees, including our principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions. The Code of Conduct is available on the “Governance & Financials” section of the “Investors & Media” page of our website www.solidbio.com. Our Board of Directors and the audit committee of our Board of Directors are responsible for overseeing the Code of Conduct. We intend to post on our website all disclosures that are required by law or the listing standards of Nasdaq concerning any amendments to, or waivers of, any provision of the Code of Conduct.

Insider Trading Policy

We have adopted an Insider Trading Policy governing the purchase, sale and/or other dispositions of our securities by our directors, officers, employees and other covered persons. We believe the Insider Trading Policy is reasonably designed to promote compliance with insider trading laws, rules and regulations, and Nasdaq listing standards. A copy of our Insider Trading Policy is filed as Exhibit 19.1 to this Annual Report on Form 10-K for the fiscal year ended December 31, 2024. We do not engage in transactions in our securities while in possession of material nonpublic information concerning the company or our securities.

Item 11. Executive Compensation.

Compensation of our Named Executive Officers

The following information describes the material elements of compensation awarded to, earned by or paid to each of our named executive officers, or the Named Executive Officers. Our Named Executive Officers for the year ended December 31, 2024 are:

•

Alexander Cumbo, our President and Chief Executive Officer;

•

Gabriel Brooks, our Chief Medical Officer; and

•

David Tyronne Howton, our Chief Operating Officer and Secretary.

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2024 Summary Compensation Table

The following table contains information about the compensation paid to or earned by each of our Named Executive Officers for the years ended December 31, 2024 and 2023.

Salary Bonus Stock Awards Option Awards All Other Compensation Total

Name and Principal Position Year ($) ($) (1) ($) (2) ($) (3) ($) (4) ($)

(4) Reflects a matching contribution under our 401(k) plan.

Narrative Disclosure to Summary Compensation Table

Base Salary. We use base salaries to recognize the experience, skills, knowledge and responsibilities required of all our employees, including our Named Executive Officers. None of our Named Executive Officers is currently party to an employment agreement or other agreement or arrangement that provides for automatic or scheduled increases in base salary.

In 2024, the annualized base salaries of our Named Executive Officers were as follows: $608,400 for Mr. Cumbo, $468,000 for Dr. Brooks and $473,200 for Mr. Howton. For 2025, our Board of Directors increased the base salary amount for Mr. Cumbo to $650,900, for Dr. Brooks to $502,100 and for Mr. Howton to $513,400.

Annual Bonus. Our Board of Directors may, in its discretion, award bonuses to our Named Executive Officers from time to time. Our employment agreements with our Named Executive Officers provide that they will be eligible for annual performance-based bonuses up to a specified percentage of their salary, subject to approval by our Board of Directors. Performance-based bonuses, which are calculated as a percentage of base salary, are designed to motivate our employees to achieve annual goals based on our strategic, financial and operating performance objectives. From time to time, our Board of Directors has approved discretionary annual cash bonuses to our Named Executive Officers with respect to their prior year performance.

With respect to 2024, our Board of Directors awarded a discretionary bonus of $334,620 to Mr. Cumbo, $187,200 to Dr. Brooks and $189,280 to Mr. Howton, which in each case equaled 100% of their respective target bonuses for 2024.

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With respect to fiscal year 2025 performance, Mr. Cumbo, Dr. Brooks and Mr. Howton are eligible for annual discretionary bonuses of up to 60%, 45% and 45% of their 2025 annual base salary, respectively.

Equity Incentives. Although we do not have a formal policy with respect to the grant of equity incentive awards to our executive officers, or any formal equity ownership guidelines applicable to them, we believe that equity grants provide our executives with a strong link to our long-term performance, create an ownership culture and help to align the interests of our executives and our stockholders. In addition, we believe that equity grants with a time-based vesting feature promote executive retention because this feature incentivizes our executive officers to remain in our employment during the vesting period. Accordingly, our Board of Directors and compensation committee periodically review the equity incentive compensation of our Named Executive Officers and from time to time may grant equity incentive awards to them in the form of stock options or RSUs with time-based and/or performance-based vesting conditions.

In February 2024, we granted options to purchase 240,250, 87,500 and 117,500 shares of our common stock to Mr. Cumbo, Dr. Brooks and Mr. Howton, respectively, and RSUs with respect to 120,125, 43,750 and 58,750 shares of our common stock to Mr. Cumbo, Dr. Brooks and Mr. Howton, respectively. The options vest with respect to 25% of the shares underlying the options on the first anniversary of the grant date and as to an additional 2.0833% of the original number of shares underlying the option monthly thereafter through the fourth anniversary of the grant date. The RSUs vest in equal annual installments over a term of four years from the date of grant.

In June 2024, we granted PSUs with respect to 677,604, 235,389, and 317,365 shares of our common stock to Mr. Cumbo, Dr. Brooks and Mr. Howton, respectively. The PSUs provide for the vesting of 25% of the target number of underlying units granted upon the achievement of each of four independent performance milestones predetermined by the Board of Directors, or the Performance Milestones, subject to continued service with us, or the Approval Conditions.

The Performance Milestones are tied to the achievement of certain business objectives and are non-market and non-financial in nature. The Board of Directors will determine that all Approval Conditions have been satisfied and the number of units that will ultimately vest on the 2026 Evaluation Date, which will occur in the first quarter of 2026, and the 2027 Evaluation Date, which will occur in the first quarter of 2027. A maximum of 25% of the target number of PSUs may vest at the 2026 Evaluation Date and the percentage of the target number of PSUs allocable to any Performance Milestone that has not been achieved on or prior to the 2027 Evaluation Date shall be cancelled.

In January 2025, we granted RSUs with respect to 401,600, 112,900, and 169,100 shares of our common stock to Mr. Cumbo, Mr. Brooks, and Mr. Howton respectively. The RSUs vest in equal annual installments over four years from the date of grant.

Our employees and executives are eligible to receive stock options and other stock-based awards pursuant to our Amended and Restated 2020 Equity Incentive Plan, or the 2020 Plan. We use equity awards to compensate our executive officers in the form of initial grants in connection with the commencement of employment and also at various times, often but not necessarily annually. None of our executive officers is currently party to an employment agreement that provides for an automatic award of stock options, RSUs or PSUs. We have granted stock options and RSUs to our executive officers with time-based vesting. The options that we have granted to our executive officers typically become exercisable as to 25% of the shares underlying the option on the first anniversary of the grant date and as to an additional 2.0833% of the original number of shares underlying the option monthly thereafter through the fourth anniversary of the grant date. The RSUs that we have granted to our executive officers typically become exercisable as to 25% of the shares underlying the RSU on the first anniversary of the grant date and as to an additional 25% of the original number of shares underlying the RSU annually thereafter. In 2024, we also granted to our executive officers the PSUs as described above. Vesting rights cease upon termination of employment and exercise rights cease shortly after termination, except that vesting of certain equity awards is fully accelerated upon certain terminations in connection with a change of control and exercisability is extended in the case of death or disability. Prior to the exercise of an option or the vesting of an RSU or PSU, the holder has no rights as a stockholder with respect to the shares subject to such option or with respect to the RSUs or PSUs, including no voting rights and no right to receive dividends or dividend equivalents.

The exercise price of all stock options granted after the closing of our initial public offering is equal to the fair market value of shares of our common stock on the date of grant, which is determined by reference to the closing market price of our common stock on The Nasdaq Global Select Market on the date of grant.

Employment and Other Agreements

We have entered into employment agreements with each of our executive officers. The employment agreements set forth the terms of the executive officers' compensation, including their base salary and annual performance bonus opportunity. In addition, the employment agreements provide that, subject to eligibility requirements under the plan documents governing such programs and our policies, the executive officers are entitled, on the same basis as our other employees, to participate in

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and receive benefits under, any medical, vision and dental insurance policy maintained by us and we will pay, consistent with our then-current employee benefit policy, a portion of the cost of the premiums for any such insurance policy in which the executive officers elect to participate. Each executive officer is also eligible to receive paid vacation time, sick time, and Company holidays consistent with our policies as then in effect from time to time and equity awards at such times and on such terms and conditions as the Board of Directors may determine. Each executive officer's employment is at will. The employment agreements with Mr. Cumbo, Dr. Brooks and Mr. Howton are summarized below.

On September 29, 2022, we entered into an employment agreement with each of Mr. Cumbo and Mr. Howton pursuant to which, effective as of December 2, 2022, Mr. Cumbo commenced employment as our President and Chief Executive Officer and Mr. Howton commenced employment as our Chief Administrative Officer, General Counsel and Secretary. Mr. Howton now serves as our Chief Operating Officer, and Secretary. On October 2, 2023, we entered into an employment agreement with Dr. Brooks, pursuant to which Dr. Brooks commenced employment as our Chief Medical Officer effective as of October 2, 2023.

Pursuant to their respective employment agreements, Mr. Cumbo was initially entitled to an annual base salary of $585,000, Dr. Brooks was initially entitled to an annual base salary of $450,000 and Mr. Howton was initially entitled to an annual base salary of $455,000. Each of their base salaries for 2024 and 2025 is set forth above under “—Narrative Disclosure to Summary Compensation Table”. Each of their base salaries will be reviewed by our Board of Directors from time to time and is subject to change in the discretion of our Board of Directors.

Mr. Cumbo, Dr. Brooks and Mr. Howton are also eligible to earn an annual performance bonus, with a target bonus amount equal to a specified percentage of their annual base salary, based upon our Board of Directors' assessment of their performance and our attainment of targeted goals as set by our Board of Directors in their sole discretion. The bonus may be in the form of cash, equity award(s), or a combination of cash and equity award(s). Pursuant to their employment agreements, Mr. Cumbo, Dr. Brooks and Mr. Howton are eligible for annual discretionary bonuses of up to 55%, 40% and 40% of their annual base salary, respectively. Mr. Cumbo, Dr. Brooks and Mr. Howton must be employed on the date that bonuses are paid in order to receive their respective bonus, provided that if such executive is terminated by us without cause (as "cause" is defined in their respective employment agreements) between January 1 of the year following the performance year and the date of payment, such executive will be entitled to the same bonus that he would have received had he remained employed through the payment date.

In accordance with Mr. Cumbo's employment agreement, on December 2, 2022, we granted Mr. Cumbo an option, or the Cumbo Option, to purchase 228,900 shares of our common stock, at an exercise price per share equal to $6.77, which vested as to 25% of the shares underlying the Cumbo Option on the first anniversary of the grant date and vests as to an additional 1/48th of the total shares underlying the Cumbo Option upon his completion of each additional month of service over the 36-month period measured from the first anniversary of the grant date. We also granted Mr. Cumbo RSUs with respect to 114,449 shares of our common stock, or the Cumbo RSU, which vests as to 25% of the shares underlying the Cumbo RSU on each anniversary of December 2, 2022, subject to continued service. The Cumbo Option and the Cumbo RSU were granted as an inducement material to Mr. Cumbo's acceptance of employment with us in accordance with Nasdaq Listing Rule 5635(c)(4).

In accordance with Dr. Howton’s employment agreement, on December 2, 2022, we granted Mr. Howton an option, or the Howton Option, to purchase 104,410 shares of our common stock, at an exercise price per share equal to $6.77, which vested as to 25% of the shares underlying the Howton Option on the first anniversary of the grant date and vests as to an additional 1/48th of the total shares underlying the Howton Option upon his completion of each additional month of service over the 36-month period measured from the first anniversary of the grant date. We also granted Mr. Howton RSUs with respect to 52,205 shares of our common stock, or the Howton RSU, which vests as to 25% of the shares underlying the Howton RSU on each anniversary of December 2, 2022, subject to continued service. The Howton Option and the Howton RSU were granted as an inducement material to Mr. Howton's acceptance of employment with us in accordance with Nasdaq Listing Rule 5635(c)(4).

In accordance with Dr. Brook’s employment agreement, on October 18, 2023, we granted Dr. Brooks an option, or the Brooks Option, to purchase 78,000 shares of our common stock, at an exercise price per share equal to $2.15, which vested as to 25% of the shares underlying the Brooks Option on the first anniversary of the grant date and vests as to an additional 1/48th of the total shares underlying the Brooks Option upon his completion of each additional month of service over the 36-month period measured from the first anniversary of the grant date. We also granted Dr. Brooks RSUs with respect to 39,000 shares of our common stock, or the Brooks RSU, which vests as to 25% of the shares underlying the Brooks RSU on each anniversary of October 18, 2023, subject to continued service.

Mr. Cumbo, Dr. Brooks and Mr. Howton are bound by proprietary rights, non-disclosure, developments, non-competition and non-solicitation obligations pursuant to the restrictive covenants provided for in their respective employment agreements.

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Under these restrictive covenants, each executive agrees not to compete with us during his employment and for a period of one year after the termination of his employment, not to solicit our employees, consultants, or actual or prospective customers or business relations during his employment and for a period of one year after the termination of his employment, and to protect our confidential and proprietary information indefinitely. In addition, under these restrictive covenants, each executive agrees that we own all inventions that are developed by him during a specified period of time with respect to any inventions made by him that are related to his activities while employed by us.

The employment of each of Mr. Cumbo, Dr. Brooks and Mr. Howton may be terminated as follows: (1) upon the death of the executive or at our election due to the executive's "disability" (as disability is defined in the applicable employment agreement); (2) at our election, with or without "cause” (as cause is defined in the applicable employment agreement); and (3) at such executive's election, with or without "good reason" (as good reason is defined in the applicable employment agreement).

In the event of the termination of employment of Mr. Cumbo, Dr. Brooks or Mr. Howton by us without cause, or by such executive for good reason, prior to, or more than 12 months, in the case of Mr. Cumbo and Mr. Howton, and 18 months, in the case of Dr. Brooks, following a "change in control" (as change in control is defined in the applicable employment agreement), the executive is entitled to receive his base salary that has accrued and to which he is entitled as of the termination date, to the extent consistent with our policy, accrued but unused paid time off through and including the termination date, unreimbursed business expenses for which expenses the executive has timely submitted appropriate documentation, and other amounts or benefits to which the executive is entitled in accordance with the terms of the benefit plans then-sponsored by us, which we refer to collectively as the Accrued Obligations. In addition, subject to the executive's execution and nonrevocation of a release of claims in our favor, the executive is entitled to (1) continued payment of his base salary, in accordance with our regular payroll procedures, for a period of 12 months, (2) in the case of Dr. Brooks, a lump sum payment equal to 100% of his target bonus for the year in which his employment is terminated, or, if higher, his target bonus immediately prior to the change in control, prorated through his date of termination and (3) provided he is eligible for and timely elects to continue receiving group medical insurance under COBRA and the payments would not result in the violation of nondiscrimination requirements of applicable law, payment by us of the portion of health coverage premiums we pay for similarly-situated, active employees who receive the same type of coverage, for a period of up to 12 months following his date of termination.

In the event of the termination of employment of Mr. Cumbo, Dr. Brooks or Mr. Howton by us without cause, or by such executive for good reason, within 12 months, in the case of Mr. Cumbo and Mr. Howton, and 18 months, in the case of Dr. Brooks, following a change in control, the executive is entitled to receive the Accrued Obligations. In addition, subject to the executive’s execution and nonrevocation of a release of claims in our favor, the executive is entitled to (1) continued payment of his base salary, in accordance with our regular payroll procedures, for a period of 18 months, in the case of Mr. Cumbo, and 12 months, in the case of Mr. Tan and Mr. Howton, (2) provided the executive is eligible for and timely elects to continue receiving group medical insurance under COBRA and the payments would not result in the violation of nondiscrimination requirements of applicable law, payment by us of the portion of health coverage premiums we pay for similarly-situated, active employees who receive the same type of coverage, for a period of up to 18 months, in the case of Mr. Cumbo, and 12 months, in the case of Dr. Brooks and Mr. Howton, following his date of termination, (3) a lump sum payment equal to 150%, in the case of Mr. Cumbo, and 100%, in the case of Dr. Brooks and Mr. Howton, of the executive's target bonus for the year in which his employment is terminated or, if higher, the executive's target bonus immediately prior to the change in control and (4) full vesting acceleration of any then-unvested equity awards that vest based solely based on the passage of time held by the executive, such that any such equity awards held by the executive become fully exercisable or non-forfeitable as of the termination date.

If the employment of Mr. Cumbo, Dr. Brooks or Mr. Howton is terminated for any other reason, including as a result of his death or disability, for cause, or voluntarily by him without good reason, our obligations under such employment agreement cease immediately, and the executive is only entitled to receive the Accrued Obligations.

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Outstanding Equity Awards at 2024 Fiscal Year-End

The following table sets forth information regarding equity awards held by our Named Executive Officers as of December 31, 2024.

Option Awards Stock Awards

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Policies and Practices Related to the Grant of Equity Awards

We grant equity awards, including stock options and/or restricted stock units, to our employees on an annual basis. We grant stock options to our directors on an annual basis. We may also grant stock options and/or restricted stock units to individuals upon hire or promotion or for retention purposes. We currently do not grant stock appreciation rights or similar option-like instruments. During the year ended December 31, 2024, neither the Board of Directors nor the compensation committee took material nonpublic information into account when determining the timing or terms of equity awards, nor did we time the disclosure of material nonpublic information for the purpose of affecting the value of executive compensation.

While we do not have any policy or obligation that requires us to grant equity awards on specified dates, annual stock option and/or restricted stock unit grants to employees are typically approved in January or February of each year. During the year ended December 31, 2024, new hire equity grants were made by our Chief Executive Officer on the first business day of the month following such employee’s hire pursuant to delegated authority under our 2024 Inducement Stock Incentive Plan. Our Chief Executive Officer does not take into account material nonpublic information when determining the timing or terms of such equity grants. Under our non-employee director compensation program, our annual stock option grants to directors are granted on the date of our annual meeting of stockholders.

During the year ended December 31, 2024, we did not grant stock options to any named executive officer during any period beginning four business days before and ending one business day after the filing of any Form 10-Q or Form 10-K, or the filing or furnishing of a Form 8-K that discloses material nonpublic information.

Non-Employee Director Compensation

Non-employee director compensation is set by our Board of Directors at the recommendation of our compensation committee. In 2024, the compensation committee retained Radford, an AON Hewitt company, to assist in assessing our non-employee director compensation program and provide recommendations with respect to the compensation program.

Under our current director compensation program, we pay our non-employee directors a cash retainer for their service on the Board of Directors and for their service on each committee of which the director is a member. The chairs of each committee receive higher retainers for such service. These fees are payable in arrears in equal semi-annual installments not later than the 15th business day following the end of the second and fourth calendar quarters, provided that the amount of such payment will be prorated for any portion of such semi-annual period that the director is not serving on the Board of Directors, on such committee or in such position. The fees paid to non-employee directors for their service on the Board of Directors and for their service on each committee of the Board of Directors of which the director is a member are as follows:

Member Annual Fee ($) Chairperson Incremental Annual Fee ($)

Nominating and Corporate Governance Committee 4,000 4,000

We also reimburse our non-employee directors for reasonable out-of-pocket business expenses incurred in connection with the performance of their duties as directors, including travel expenses in connection with their attendance in person at our Board of Directors and committee meetings.

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In addition, under our current director compensation program, each new non-employee director elected to our Board of Directors will receive an option to purchase 68,800 shares of our common stock under the 2020 Plan. Each of these options vests in equal annual installments over a three-year period measured from the date of grant, subject to the director’s continued service as a director. Further, on the date of our annual meeting of stockholders, each non-employee director that has served on our Board of Directors for at least six months prior to such annual meeting will receive an option to purchase 34,400 shares of our common stock under our 2020 Plan. Each of these options vests in full on the earlier to occur of the one-year anniversary of the grant date and immediately prior to our first annual meeting of stockholders occurring after the grant date, subject to the director’s continued service as a director. All options granted to our non-employee directors under our director compensation program will be issued at exercise prices equal to the fair market value of our common stock on the date of grant and will become exercisable in full in the event of a change in control.

This program is intended to provide compensation for our non-employee directors in a manner that enables us to attract and retain outstanding director candidates and reflects the substantial time commitment necessary to oversee our affairs. We also seek to align the interests of our directors and our stockholders, and we have chosen to do so by compensating our non-employee directors with a mix of cash and equity-based compensation.

The table below shows the compensation paid to our non-employee directors during 2024.

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our non-employee director compensation program.

(8) Resigned from our Board of Directors effective June 11, 2024.

In respect of his services as Executive Chairman of our Board of Directors, on January 6, 2025, we granted Mr. Smith an option to purchase 22,148 shares of our common stock and 18,293 RSUs.

Annie Ganot, who is the wife of Ilan Ganot and one of our co-founders, serves as our Vice President, Patient Advocacy. The compensation she receives in connection with such service is set forth in Item 13, “Certain Relationships and Related Transactions, and Director Independence” of this Annual Report on Form 10-K.

During 2024, we did not provide any compensation to Mr. Cumbo, our President and Chief Executive Officer, for his service as a member of our Board of Directors. Mr. Cumbo’s compensation for his service as an executive officer is set forth above under “Compensation of our Named Executive Officers — 2024 Summary Compensation Table.”

Compensation Committee Interlocks and Insider Participation

None of the current members of our compensation committee has ever been an executive officer or employee of ours. None of our executive officers currently serves, or has served during the last completed fiscal year, on the compensation committee or board of directors of any other entity that has one or more executive officers serving as a member of our Board of Directors or compensation committee.

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

Security Ownership of Certain Beneficial Owners and Management

The following table sets forth information regarding the beneficial ownership of our common stock as of February 24, 2025 by (i) each person whom we know to beneficially own more than 5% of our outstanding common stock, which we refer to as a 5%stockholder, (ii) each director, (iii) each Named Executive Officer and (iv) all current directors and executive officers as a group. Unless otherwise indicated, the address of each executive officer and director is c/o Solid Biosciences Inc., 500 Rutherford Avenue, 3rd Floor, Charlestown, Massachusetts 02129.

The number of shares of common stock "beneficially owned" by each stockholder is determined under rules issued by the SEC regarding the beneficial ownership of securities. This information is not necessarily indicative of beneficial ownership for any other purpose. Under these rules, beneficial ownership of shares of our common stock includes (1) any shares as to which the person or entity has sole or shared voting power or investment power and (2) any shares as to which the person or entity has the right to acquire beneficial ownership within 60 days after February 24, 2025. The percentage of beneficial ownership in the table below is based on 76,516,805 shares of common stock deemed to be outstanding as of February 24, 2025.

Unless otherwise indicated below, and subject to community property laws where applicable, to our knowledge, all persons named in the table have sole voting and investment power with respect to their shares of common stock.

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5% Stockholders:

Entities affiliated with RA Capital Management, L.P.(2) 8,011,678 9.99 %

Invus Public Equities, L.P. and affiliated entities (4) 7,415,905 9.69 %

Entities managed by Vestal Point Capital, LP (6) 4,288,850 5.61 %

Named Executive Officers and Directors:

* Less than 1 percent

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Securities Authorized for Issuance under Equity Compensation Plans

The following table provides information about our equity compensation plans as of December 31, 2024. As of December 31, 2024, we had four equity compensation plans: our 2018 Omnibus Incentive Plan, our 2020 Plan, our Amended and Restated 2021 Employee Stock Purchase Plan, or the ESPP, each of which was approved by our stockholders, and our 2024 Inducement Stock Incentive Plan, which plan was not approved by our stockholders. We have also made inducement awards outside of our equity compensation plans to certain new hires, which awards were not approved by our stockholders.

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Name Options(1) RSUs(2) Grant Date

President, Chief Executive Officer and Director

Chief Financial Officer and Treasurer

Chief Operating Officer and Secretary

Chief Regulatory Officer

Chief Technology Officer

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

Transactions with Related Persons

In addition to the executive officer and director compensation arrangements discussed in Item 11, “Executive Compensation” of this Annual Report on Form 10-K, the following describes transactions since January 1, 2023 to which we have been or will be a participant, in which the amount involved in the transaction exceeds the lesser of $120,000 or 1% of our total assets at year end for each of the last two completed fiscal years and in which any of our directors, executive officers or beneficial holders of more than 5% of any class of our capital stock, or any immediate family member of, or person sharing the household with, any of these individuals, had or will have a direct or indirect material interest.

Amended and Restated Registration Rights Agreement

We are party to an Amended and Restated Registration Rights Agreement, or the Registration Rights Agreement, dated March 29, 2017, with certain of our stockholders, or the Investors, which includes holders of more than 5% of our voting securities and entities affiliated with certain of our directors. The Registration Rights Agreement provides the Investors the right, subject to certain conditions, to demand that we file a registration statement or to request that their shares be covered by a registration statement that we are otherwise filing.

February 2025 Underwritten Registered Offering

On February 19, 2025, we closed an underwritten offering in which we issued and sold an aggregate of 35,739,810 shares of our common stock at a price per share of $4.03 and pre-funded warrants to purchase 13,888,340 shares of our common stock at a price per warrant of $4.029, before expenses and underwriting discounts and commissions. We received aggregate net proceeds of approximately $187.5 million, after deducting expenses and underwriting discounts and commissions. The number of shares that our holders of more than 5% of our voting securities purchased and the aggregate purchase price paid for such shares is set forth in the table below.

January 2024 Private Placement

On January 8, 2024, we entered into a securities purchase agreement with respect to the private placement of an aggregate of 16,973,103 shares of our common stock at a price of $5.53 per share, and, to one investor in lieu of shares, pre-funded warrants to purchase 2,712,478 shares of our common stock, at a price of $5.529 per pre-funded warrant. We received $103.7 million in aggregate net proceeds from the private placement, after deducting offering costs. The number of shares purchased by the holders of more than 5% of our voting securities at the time of the private placement and the aggregate purchase price paid for such shares is set forth in the table below.

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Name (1) Shares of Common Stock Purchased(#) Purchase Price($)

Arrangements with Ian F. Smith

Mr. Smith became our Executive Chairman, effective January 1, 2022. The compensation that we have paid to Mr. Smith in connection with his services as Executive Chairman and as our non-employee director is discussed above in Item 11, “Executive Compensation” of this Annual Report on Form 10-K.

Arrangements with Ilan Ganot

Mr. Ganot is a member of our Board of Directors and served as our President and Chief Executive Officer until December 2022. On September 29, 2022, we entered into an Executive Transition and Separation Agreement with Mr. Ganot, or the Ganot Transition Agreement, which became effective as of December 2, 2022, or the Separation Date. Pursuant to the Ganot Transition Agreement, Mr. Ganot was entitled to (1) continued payment of his base salary, in accordance with our regular payroll procedures, for a period of 18 months from the Separation Date (an aggregate of $868,050) and (2) provided he was eligible for and timely elected to continue receiving group medical insurance under COBRA and the payments would not result in the violation of nondiscrimination requirements of applicable law, payment by us of the portion of health coverage premiums we pay for similarly-situated, active employees who receive the same type of coverage, for a period of up to 18 months following the Separation Date. Mr. Ganot also received $477,427, less applicable taxes and withholdings, which is a lump sum payment equal to 150% of his target bonus for 2022.

On September 29, 2022, we also entered into a Consulting Agreement with Mr. Ganot, or the Ganot Consulting Agreement, effective as of the Separation Date, pursuant to which Mr. Ganot assisted us with the transition of his duties to Mr. Cumbo and provided other consulting and advisory services, as requested from time to time by us. The Ganot Consulting Agreement expired by its terms in December 2023. Mr. Ganot was compensated at a rate of $20,833 per month for his services under the agreement for a total of $250,000.

We employ Ms. Ganot, one of our co-founders and the wife of Ilan Ganot, as our Vice President, Patient Advocacy. For 2023 and 2024, Ms. Ganot received annual salary and bonus payments of $360,380 and $374,795, respectively. For 2025 we expect Ms. Ganot will receive annual salary and bonus payments of less than $475,000 in the aggregate. In January 2023, February 2024 and February 2025, we granted (i) an option to purchase 23,950 shares of our common stock and RSUs with respect to 11,975 shares of our common stock, (ii) RSUs with respect to 19,444 shares of our common stock and (iii) RSUs with respect to 60,000 shares of our common stock, respectively, to Ms. Ganot relating to her service as our Vice President, Patient Advocacy. The options vest over a term of four years, with 25% of the original number of shares vesting on the first anniversary of the date of grant and 2.0833% of the original number of shares on the first day of each calendar month thereafter until the fourth such anniversary. The RSUs vest in equal annual installments over a term of four years from the date of grant.

For further information about the compensation received by Mr. Ganot in 2024, see “Non-Employee Director Compensation” in Item 11, “Executive Compensation” of this Annual Report on Form 10-K.

Arrangements with Carl Morris

Carl Morris served as our Chief Scientific Officer, Neuromuscular until July 14, 2023, or the Morris Separation Date. On May 22, 2023, we entered into an executive transition and separation agreement with Dr. Morris, or the Morris Transition and Separation Agreement. On the Morris Separation Date, we also entered into a consulting agreement, or the Morris Consulting Agreement, pursuant to which Dr. Morris assisted with the transition of his duties and provided other consulting and advisory services, as requested from time to time by us.

Pursuant to the Morris Transition Separation Agreement, Dr. Morris was entitled to receive all unpaid base salary earned through the Morris Separation Date, any amounts for accrued unused paid time off to which he was entitled through such

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date in accordance with our policy, and reimbursement of any properly incurred unreimbursed business expenses incurred through such date. In addition, contingent on his providing a release of claims, Dr. Morris was entitled to (1) severance equal to a year’s base salary, paid ratably over 12 months from the Morris Separation Date (an aggregate of $430,500), (2) provided he was eligible for and timely elected to continue receiving group health insurance under COBRA, payment by us of the portion of health coverage premiums that we pay for similarly-situated, active employees who receive the same type of coverage, for a period of up to 12 months following the Morris Separation Date, and (3) $172,200, less applicable taxes and withholdings, which is a lump sum payment equal to 100% of his target bonus for 2023. In January 2023, we granted options to purchase 95,100 shares of our common stock and RSUs with respect to 47,555 shares of our common stock to Dr. Morris. The options vested with respect to 25% of the shares underlying the options on the first anniversary of the grant date and as to an additional 2.0833% of the original number of shares underlying the options monthly thereafter through the fourth anniversary of the grant date. The RSUs vest in equal annual installments over four years from the date of grant. In consideration for services under the Morris Consulting Agreement, Dr. Morris’ then-outstanding equity awards continued to vest and remained exercisable in accordance with the applicable equity plans and award agreements.

Arrangements with Danforth Advisors, LLC

In November 2020, we entered into a consulting agreement with Danforth Advisors, LLC, or Danforth, an affiliate of Stephen DiPalma, our former interim chief financial officer who resigned in January 2023. Pursuant to the consulting agreement, Danforth provided us with the chief financial officer services of Mr. DiPalma, and continues to provide us other services, including financial planning, offering support and accounting services, in exchange for fees payable to Danforth based on hourly rates. We have paid Danforth approximately $2.8 million to date. The consulting agreement may be terminated by either party without cause upon 60 days’ prior written notice to the other party and with cause upon 30 days’ prior written notice to the other party.

Indemnification Agreements

We have entered into agreements to indemnify our directors and executive officers. These agreements require us, among other things, to indemnify these individuals for certain expenses (including attorneys' fees), judgments, fines and settlement amounts reasonably incurred by such persons in any action or proceeding, including any action by or in our right, on account of any services undertaken by any such person on behalf of our company or that person's status as a member of our Board of Directors to the maximum extent allowed under Delaware law.

Policy for Approval of Related-Person Transactions

We have adopted a written related-person transaction policy that sets forth our procedures for the identification, review, consideration and approval or ratification of any transaction, arrangement or relationship in which we are a participant, the amount involved exceeds $120,000 and one of our executive officers, directors, director nominees or 5% stockholders (or their immediate family members), each of whom we refer to as a "related person," has a direct or indirect material interest.

If a related person proposes to enter into such a transaction, arrangement or relationship, which we refer to as a "related-person transaction," the related person must report the proposed related-person transaction to our general counsel. The policy calls for the proposed related-person transaction to be reviewed by and if deemed appropriate approved by, the audit committee of our Board of Directors. Whenever practicable, the reporting, review and approval will occur prior to entry into the transaction. If advance review and approval is not practicable, the audit committee will review and, in its discretion, may ratify the related-person transaction. The policy also permits the chair of the audit committee to review, and if deemed appropriate approve, proposed related-person transactions that arise between audit committee meetings, subject to ratification by the audit committee at its next meeting. Any related-person transactions that are ongoing in nature will be reviewed annually.

A related-person transaction reviewed under the policy will be considered approved or ratified if it is authorized by the audit committee after full disclosure of the related person's interest in the transaction. As appropriate for the circumstances, the committee will review and consider:

•

the related person’s interest in the related-person transaction;

•

the approximate dollar amount involved in the related-person transaction;

•

the approximate dollar amount of the related person’s interest in the transaction without regard to the amount of any profit or loss;

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•

whether the transaction was undertaken in the ordinary course of our business;

•

whether the terms of the transaction are no less favorable to us than terms that could have been reached with an unrelated third party;

•

the purpose of, and the potential benefits to us of, the related-person transaction; and

•

any other information regarding the related-person transaction or the related person in the context of the proposed transaction that would be material to investors in light of the circumstances of the particular transaction.

The audit committee may approve or ratify the transaction only if the audit committee determines that, under all of the circumstances, the transaction is not inconsistent with our best interests. The audit committee may impose any conditions on the related-person transaction that it deems appropriate.

The policy provides that transactions involving compensation of executive officers will be reviewed and approved by the compensation committee of our Board of Directors in the manner specified in its charter.

Director Independence

Nasdaq rules require a majority of a listed company's board of directors to be comprised of independent directors. In addition, Nasdaq rules require that, subject to specified exceptions, each member of a listed company's audit, compensation and nominating and corporate governance committees be independent. Audit committee members must also satisfy independence criteria set forth in Rule 10A-3 under the Securities Exchange Act of 1934, as amended, or the Exchange Act, and compensation committee members must also satisfy the independence criteria set forth in Rule 10C-1 under the Exchange Act. The Nasdaq independence definition includes a series of objective tests, such as that the director is not, and has not been for at least three years, one of our employees and that neither the director nor any of his or her family members has engaged in various types of business dealings with us. In addition, under applicable Nasdaq rules, a director will only qualify as an "independent director" if, in the opinion of the listed company's board of directors, that person does not have a relationship that would interfere with the exercise of independent judgment in carrying out the responsibilities of a director. In order to be considered independent for purposes of Rule 10A-3, a member of an audit committee of a listed company may not, other than in his or her capacity as a member of the audit committee, the board of directors, or any other board committee, accept, directly or indirectly, any consulting, advisory, or other compensatory fee from the listed company or any of its subsidiaries or otherwise be an affiliated person of the listed company or any of its subsidiaries. In order to be considered independent for purposes of Rule 10C-1, the board must consider, for each member of a compensation committee of a listed company, all factors specifically relevant to determining whether a director has a relationship to such company which is material to that director's ability to be independent from management in connection with the duties of a compensation committee member, including, but not limited to: (1) the source of compensation of the director, including any consulting advisory or other compensatory fee paid by such company to the director; and (2) whether the director is affiliated with the company or any of its subsidiaries or affiliates.

Our Board of Directors has determined that all members of the Board of Directors, except Alexander Cumbo and Ilan Ganot, are independent directors, as defined under applicable Nasdaq rules. In March 2024, our Board of Directors also previously determined that Adam Koppel and Rajeev Shah, former directors who resigned from our board of directors, effective June 11, 2024, were independent directors, as defined under applicable Nasdaq rules. In making such determinations, our Board of Directors considered the relationships that each director has with our Company and all other facts and circumstances that our Board of Directors deemed relevant in determining his or her independence, including the beneficial ownership of our common stock by each director. Mr. Cumbo is not an independent director under applicable rules because he is our President and Chief Executive Officer. Mr. Ganot is not an independent director under applicable rules because he was our President and Chief Executive Officer until December 2, 2022.

Our Board of Directors has determined that the composition of our committees currently complies with all applicable independence requirements of Nasdaq and the rules and regulations of the SEC.

Item 14. Principal Accountant Fees and Services.

The following table represents aggregate fees billed to us by PricewaterhouseCoopers LLP, our independent registered public accounting firm, for the fiscal years ended December 31, 2024 and 2023:

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Year Ended December 31,

Audit-related fees — —

The services rendered by PricewaterhouseCoopers LLP in connection with the fees presented above were as follows:

Audit Fees

Audit fees consist of fees billed for professional services for the audit of our annual consolidated financial statements, the review of interim consolidated financial statements, and related services that are normally provided in connection with registration statements.

Tax Fees

Tax fees consist of fees for professional services related to tax compliance and consultations.

All Other Fees

All other fees include license fees for web-based accounting research tools.

Pre-Approval Policies

The audit committee has not adopted policies and procedures for the pre-approval of audit and non-audit services rendered by our independent registered public accounting firm and, consequently, all audit and non-audit services are pre-approved by the whole audit committee or the chair of the audit committee. All fees for the fiscal years ended December 31, 2024 and 2023 were so pre-approved.

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PART IV

Item 15. Exhibits and Financial Statement Schedules.

(1) Financial Statements:

Page

Report of Independent Registered Public Accounting Firm (PCAOB ID 238) F-1

Consolidated Balance Sheets at December 31, 2024 and 2023 F-3

Notes to Consolidated Financial Statements F-9

(2) Financial Statement Schedules:

All financial statement schedules have been omitted because they are not applicable, not required or the information required is shown in the 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.

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ExhibitNumber Description

10.10*† Summary of Non-Employee Director Compensation Program

130

131

19.1* Insider Trading Policy.

21.1* Subsidiaries of Solid Biosciences Inc.

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101.INS Inline XBRL Instance Document.

* Filed herewith.

** Furnished herewith.

† Indicates management contract or compensatory plan.

# Certain portions of this exhibit have been omitted because they are not material and contain information that the Registrant customarily and actually treats as private or confidential.

## Filed with this Annual Report on Form 10-K solely for the purpose of transitioning this previously-filed exhibit, which is the subject of expiring confidential treatment orders, to the rules governing the filing of redacted exhibits under Regulation S-K Item 601(b)(10)(iv) pursuant to the SEC’s CF Disclosure Guidance: Topic 7. Portions of this exhibit have been omitted pursuant to Item 601(b)(10)(iv) of Regulation S-K.

Item 16. Form 10-K Summary.

Not applicable.

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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.

SOLID BIOSCIENCES INC.

Date: March 6, 2025 By: /s/ Alexander Cumbo

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.

/s/ Ian F. Smith Ian F. Smith Executive Chairman of the Board March 6, 2025

/s/ Martin Freed Martin Freed Director March 6, 2025

/s/ Ilan Ganot Director March 6, 2025

Ilan Ganot

/s/ Clare Kahn Director March 6, 2025

Clare Kahn

/s/ Georgia Keresty Director March 6, 2025

Georgia Keresty

/s/ Sukumar Nagendran Sukumar Nagendran Director March 6, 2025

/s/ Adam Stone Adam Stone Director March 6, 2025

/s/ Lynne Sullivan Lynne Sullivan Director March 6, 2025

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Report of Independent Registered Public Accounting Firm

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

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of Solid Biosciences, Inc. and its subsidiaries (the “Company”) as of December 31, 2024 and 2023, and the related consolidated statements of operations, of comprehensive loss, of changes in stockholders’ equity and of cash flows for the years then ended, including the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2024 and 2023, and the results of its operations and its cash flows for the years then ended in conformity with accounting principles generally accepted in the United States of America.

Basis for Opinion

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

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

Our audits included performing procedures to assess the risks of material misstatement of the consolidated 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 consolidated 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 consolidated financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matters

The critical audit matter communicated below is a matter arising from the current period audit of the consolidated financial statements that was communicated or required to be communicated to the audit committee and that relates to accounts or disclosures that are material to the consolidated financial communication of critical audit matters does not alter in any way our opinion on the consolidated 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.

External Research and Development Costs

As described in Note 2 to the consolidated financial statements, research and development costs are expensed as incurred. Research and development expenses include salaries, equity-based compensation and benefits of employees, third-party license fees and other operational costs related to the Company’s research and development activities, including allocated facility-related expenses and external costs of outside vendors engaged to conduct both preclinical studies and clinical trials. The Company has entered into various research and development contracts with research institutions and other companies. These agreements are generally cancellable, and related payments are recorded as research and development expenses as incurred. Management records accruals for estimated ongoing research costs. When evaluating the adequacy of the accrued liabilities, management analyzes progress of the studies, including the phase or completion of events, invoices received and

F-1

contracted costs. As disclosed by management, the majority of service providers invoice the Company in arrears for services performed, on a pre-determined schedule or when contractual milestones are met; however, some require advanced payments. The Company’s research and development expense for the year ended December 31, 2024 was $96.4 million, a majority of which relates to external research and development costs.

The principal consideration for our determination that performing procedures relating to external research and development costs is a critical audit matter is a high degree of auditor effort in performing procedures related to the Company’s external research and development costs.

Addressing the matter involved performing procedures and evaluating audit evidence in connection with forming our overall opinion on the consolidated financial statements. These procedures included, among others, testing external research and development costs on a sample basis by agreeing relevant information, including overall contract value, amounts incurred to date, and percentage of completion amounts to the (i) underlying agreements with outside vendors engaged to conduct preclinical studies and clinical trials, (ii) purchase orders, (iii) invoices received, (iv) underlying payments made for expenses incurred on the contracts, and (v) external confirmations or communications obtained by management from outside vendors.

/s/ PricewaterhouseCoopers LLP

Boston, Massachusetts

March 6, 2025

We have served as the Company's auditor since 2017.

F-2

SOLID BIOSCIENCES INC.

CONSOLIDATED BALANCE SHEETS

(In thousands, except share and per share data)

December 31,

Assets

Current assets:

Prepaid expenses and other current assets 8,382 6,094

Non-current assets:

Other non-current assets 366 209

Liabilities and Stockholders' Equity

Current liabilities:

Accrued expenses and other current liabilities 19,852 10,161

Derivative liabilities 3,150 —

Non-current liabilities:

Operating lease liabilities, net of current portion 21,159 22,707

Finance lease obligations, net of current portion — 1,234

Commitments and Contingencies (Note 11)

Stockholders’ Equity:

Accumulated other comprehensive income 47 15

Total liabilities and stockholders' equity $ 188,662 $ 164,939

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

F-3

SOLID BIOSCIENCES INC.

CONSOLIDATED STATEMENTS OF OPERATIONS

(In thousands, except share and per share data)

Year Ended December 31,

Operating expenses:

Restructuring expense — (63 )

Other income, net:

Change in fair value of derivative liabilities (4,750 ) —

Net loss per share, basic and diluted $ (3.06 ) $ (4.83 )

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

F-4

SOLID BIOSCIENCES INC.

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS

(In thousands)

Year Ended December 31,

Other comprehensive income:

Unrealized gain on available-for-sale securities 32 83