PTC THERAPEUTICS, INC.

1. The Company

PTC Therapeutics, Inc. (the “Company” or “PTC”) is a global biopharmaceutical company dedicated to the discovery, development and commercialization of clinically differentiated medicines for children and adults living with rare disorders. PTC is advancing a robust and diversified pipeline of transformative medicines as part of its mission to provide access to best-in-class treatments for patients with unmet medical needs. PTC’s strategy is to leverage its scientific expertise and global commercial infrastructure to optimize value for its patients and other stakeholders. PTC has a diversified therapeutic portfolio pipeline that includes several commercial products and product candidates in various stages of development, including clinical, pre-clinical and research and discovery stages, focused on the development of new treatments for multiple therapeutic areas for rare diseases relating to neurology and metabolism.

The Company has developed Sephience™ (sepiapterin), a product for the treatment of phenylketonuria (“PKU”), a rare inherited metabolic disease characterized by the body’s inability to break down an essential amino acid called phenylalanine, and which can result in neurological and other symptoms. In June 2025, Sephience was granted marketing authorization by the European Commission (“EC”) for the treatment of children and adults living with PKU within the European Economic Area (“EEA”). In July 2025, Sephience was approved by the U.S. Food and Drug Administration (“FDA”) for the treatment of pediatric and adult patients living with PKU in the United States age one month and above. In December 2025, Sephience was approved by the Japanese Ministry of Health, Labor, and Welfare (“MHLW”) for the treatment of children and adults living with PKU. In February 2026, Sephience was approved by ANVISA, the Brazilian health regulatory authority, for the treatment of children and adults living with PKU in Brazil. Sephience is also approved in additional geographies.

The Company hastwo products, Translarna™ (ataluren) and Emflaza® (deflazacort), for the treatment of Duchenne muscular dystrophy (“DMD”), a rare, life-threatening disorder. While Translarna previously had conditional approval in the EEA, in March 2025, the European Commission, or EC, adopted the negative opinion of the Committee of Medicinal Products for Human Use, or CHMP, of the European Medicines Agency, or EMA, to not renew the conditional marketing authorization of Translarna for the treatment of nmDMD. However, the EC indicated that individual countries within the European Union, or EU, can leverage Articles 117(3) and 5(1) of the EU Directive 2001/83 to allow continued commercial use of Translarna. Translarna has marketing authorization in additional geographies outside of the EEA, but the EC adoption of the CHMP negative opinion may affect future reauthorizations. Emflaza is approved in the United States for the treatment of DMD in patients two years and older.

Translarna is an investigational new drug in the United States. During the first quarter of 2017, the Company filed an NDA for Translarna for the treatment of nmDMD over protest with the FDA. In October 2017, the Office of Drug Evaluation I of the FDA issued a CRL for the NDA, stating that it was unable to approve the application in its current form. In response, the Company filed a formal dispute resolution request with the Office of New Drugs of the FDA. In February 2018, the Office of New Drugs of the FDA denied the Company’s appeal of the CRL. In its response, the Office of New Drugs recommended a possible path forward for the Company’s ataluren NDA submission based on the accelerated approval pathway. The Company followed the FDA’s recommendation and collected, using newer technologies via procedures and methods that the Company designed in a new study, Study 045, and announced the results of Study 045 in February 2021. Study 045 did not meet its pre-specified primary endpoint. In June 2022, the Company announced top-line results from the placebo-controlled trial of Study 041, which was its 18 months, placebo-controlled trial, followed by an 18 months open label extension, of Translarna in the treatment of ambulatory patients with nmDMD aged five years or older. Following this announcement, the Company submitted a meeting request to the FDA to gain clarity on the regulatory pathway for a potential re-submission of an NDA for Translarna. The FDA provided initial written feedback that Study 041 does not provide substantial evidence of effectiveness to support NDA re-submission. The Company held a Type C

meeting with the FDA in the fourth quarter of 2023 to discuss the totality of Translarna data. Based on feedback from the FDA, the Company re-submitted the NDA in July 2024, based on the results from Study 041 and from its international drug registry study for nmDMD patients receiving Translarna. In October 2024, the FDA accepted for review the resubmission of the NDA for Translarna for the treatment of nmDMD. Following feedback from FDA at the end of January 2026, the Company decided to withdraw the NDA resubmission for Translarna. Further development of Translarna for the treatment of nmDMD in the United States is not planned.

The Company has developed Upstaza (eladocagene exuparvovec), a gene therapy used for the treatment of Aromatic L-Amino Acid Decarboxylase (“AADC”) deficiency (“AADC deficiency”), a rare central nervous system (“CNS”) disorder arising from reductions in the enzyme AADC that results from mutations in the dopa decarboxylase gene. In July 2022, the EC approved Upstaza for the treatment of AADC deficiency for patients 18 months and older within the EEA. In November 2022, the Medicines and Healthcare Products Regulatory Agency approved Upstaza for the treatment of AADC deficiency for patients 18 months and older within the United Kingdom. In November 2024, the Company’s biologics license application (“BLA”) for its gene therapy treatment of AADC deficiency was approved by the FDA. This gene therapy is marketed under the brand name Kebilidi in the United States.

The Company holds the rights for the commercialization of Tegsedi® (inotersen) and Waylivra® (volanesorsen) for the treatment of rare diseases in countries in Latin America and the Caribbean pursuant to the Collaboration and License Agreement (the “Tegsedi-Waylivra Agreement”), dated August 1, 2018, by and between the Company and Akcea Therapeutics, Inc. (“Akcea”), a subsidiary of Ionis Pharmaceuticals, Inc. Tegsedi has received marketing authorization in the United States, the European Union (the “EU”) and Brazil for the treatment of stage 1 or stage 2 polyneuropathy in adult patients with hereditary transthyretin amyloidosis (“hATTR amyloidosis”). In August 2021, ANVISA, the Brazilian health regulatory authority, approved Waylivra as the first treatment for familial chylomicronemia syndrome (“FCS”) in Brazil. In December 2022, ANVISA approved Waylivra for the treatment of familial partial lipodystrophy (“FPL”). Waylivra has also received marketing authorization in the EU for the treatment of FCS.

The Company also has a spinal muscular atrophy (“SMA”) collaboration with F. Hoffman-La Roche Ltd and Hoffman-La Roche Inc. (referred to collectively as “Roche”) and the Spinal Muscular Atrophy Foundation (“SMA Foundation”). The SMA program has one approved product, Evrysdi® (risdiplam), which was approved by the FDA in August 2020 for the treatment of SMA in adults and children two months and older and by the EC in March 2021 for the treatment of 5q SMA in patients two months and older with a clinical diagnosis of SMA Type 1, Type 2 or Type 3 or with one to four SMN2 copies. Evrysdi has also received marketing authorization for the treatment of SMA in over 100 countries. In May 2022, the FDA approved a label expansion for Evrysdi to include infants under two months old with SMA. In August 2023, the EC approved an extension of the Evrysdi marketing authorization to include infants under two months old in the EU.

In addition to the Company’s SMA program, the Company’s splicing platform also includes votoplam (PTC518), which is being developed for the treatment of Huntington’s disease (“HD”). The Company initiated a Phase 2 study of votoplam for the treatment of HD in the first quarter of 2022, which consisted of an initial 12-week placebo-controlled phase focused on safety, pharmacology and pharmacodynamic effects followed by a nine-month placebo-controlled phase focused on votoplam biomarker effect. In June 2024, the Company announced interim results from the full Phase 2 study ofvotoplam. At month 12, votoplam treatment demonstrated durable dose-dependent lowering of mutant HTT (“mHTT”) protein in the blood and dose-dependent lowering of mHTT protein in the cerebrospinal fluid in the interim cohort of stage 2 patients. In addition, favorable trends were demonstrated on several relevant HD clinical assessments. Furthermore, following 12 months of treatment, votoplam continued to be well tolerated. In September 2024, the FDA granted Fast Track designation to thevotoplam program for the treatment of HD. In December 2024, the Company held a Type C meeting with the FDA to discuss whether huntingtin protein lowering could be considered a surrogate endpoint for

accelerated approval of votoplam. The FDA was aligned on the scientific rationale and asked to see additional data supportive of an association between huntingtin protein lowering and changes in clinical outcome scores. In May 2025, the Company announced that the Phase 2 study of votoplam met its primary endpoints of blood HTT lowering and safety. The results on the full study population are consistent with the previously reported evidence of dose-dependent HTT lowering, favorable safety profile and early signals of dose-dependent clinical effect at 12 months in Stage 2 patients. In addition, at 24 months of treatment, there were continued trends of dose-dependent favorable clinical effect relative to a propensity-matched natural history cohort as well as dose-dependent NfL lowering. In November 2024, the Company entered into a License and Collaboration Agreement (the “Novartis Agreement”) with Novartis Pharmaceuticals Corporation (“Novartis”), relating to itsvotoplam HD program which included related molecules. This transaction closed in January 2025, triggering a$1.0 billion upfront cash payment to the Company. In the fourth quarter of 2025, an End-of-Phase 2 meeting was held with FDA, and alignment was reached on design of a global Phase 3 clinical trial, which the Company expects that Novartis will initiate in the first half of 2026. This trial could serve as the confirmatory study in the context of Accelerated Approval, or as a registration trial. The Company also expects to have results from the Phase 2 PIVOT-HD extension study of votoplam in the first half of 2026, once all participants cross the 24-month time point.

The Company’s inflammation and ferroptosis platform consists of small molecule compounds that target oxidoreductase enzymes that regulate oxidative stress and inflammatory pathways central to the pathology of a number of CNS and non-CNS diseases. The most advanced molecule in the Company’s inflammation and ferroptosis platform is vatiquinone. The Company announced topline results from a registration-directed Phase 3 trial of vatiquinone in children and young adults with Friedreich’s ataxia (“FA”), called MOVE-FA, in May 2023. While the study did not meet its primary endpoint, vatiquinone treatment did demonstrate significant benefit on key disease subscales, including the upright stability subscale, as well as on other disease relevant endpoints. In October 2024, the Company announced that the pre-specified endpoint for two different FA long-term extension studies was met, with statistically significant evidence of durable treatment benefit on disease progression. In December 2024, the Company submitted an NDA to the FDA for vatiquinone for the treatment of children and adults living with FA. In February 2025, the FDA accepted for filing the NDA. In August 2025, the FDA issued a complete response letter related to the NDA stating that substantial evidence of efficacy was not demonstrated for vatiquinone and that an additional adequate and well-controlled study would be needed to support NDA resubmission. The Company met with the FDA in the fourth quarter of 2025 to discuss the vatiquinone development program. FDA suggested an additional study be conducted to support NDA resubmission. FDA stated in the meeting minutes that this study could be an open label study with a natural history control group. The Company plans to meet with FDA in the second quarter of 2026 to discuss the design of this new study.

In addition, the Company has a pipeline of product candidates and discovery programs that are in early clinical, pre-clinical and research and development stages focused on the development of new treatments for multiple therapeutic areas for rare diseases.

As of December 31, 2025, the Company had an accumulated deficit of approximately $2,964.2 million. The Company has financed its operations to date primarily through the private offerings of convertible senior notes (see Note 7), public and “at the market offerings” of common stock, proceeds from royalty purchase agreements (see Note 7), private placements of its convertible preferred stock and common stock, collaborations, bank and institutional lender debt, other convertible debt, grant funding and clinical trial support from governmental and philanthropic organizations and patient advocacy groups in the disease areas addressed by the Company’s product candidates. The Company has also relied on revenue generated from net sales of its products. The Company has also relied on revenue associated with milestone and royalty payments from Roche pursuant to the License and Collaboration Agreement (the “SMA License Agreement”) dated as of November 23, 2011, by and among the Company, Roche and, for the limited purposes set forth therein, the SMA Foundation, under its SMA program. The Company has also relied on revenues associated with the Novartis Agreement. The Company expects that cash flows from the sales of its products, milestone payments from Novartis,

together with the Company’s cash, cash equivalents and marketable securities, will be sufficient to fund its operations for at least the next twelve months.

2. Summary of significant accounting policies

Basis of presentation

The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) and include all adjustments necessary for the fair presentation of the Company’s financial position for the periods presented.

Use of estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Significant estimates in these consolidated financial statements have been made in connection with the calculation of net product sales, royalty revenue, certain accruals related to the Company’s research and development expenses, valuation procedures for liability for sale of future royalties, and the provision for or benefit from income taxes. Actual results could differ from those estimates. Changes in estimates are reflected in reported results in the period in which they become known.

Restricted Cash

Restricted cash included in deposits and other assets on the consolidated balance sheet contains an unconditional, irrevocable and transferable letter of credit of $3.0 million in connection with an amendment and restatement of the Company’s lease in Hopewell Township, New Jersey. Restricted cash also contains an unconditional, irrevocable and transferable letter of credit of $10.0 million in connection with obligations for the Company’s new facility lease in Warren, New Jersey. If after July 1, 2027, the Company is not in default of the lease agreement and meets certain creditworthiness guidelines, then the letter of credit will be reduced to $5.0 million. If after December 31, 2028, the Company is not in default of the lease agreement and meets certain creditworthiness guidelines, then the letter of credit will be further reduced to $2.5 million. Both letters of credit are classified within deposits and other assets on the consolidated balance sheet due to the long-term nature of the letters of credit. Restricted cash also includes a bank guarantee of $0.7 million denominated in a foreign currency.

The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the consolidated balance sheet that sum to the total of the same amounts shown in the statement of cash flows:

Consolidation

The consolidated financial statements include the accounts of PTC Therapeutics, Inc. and its wholly owned subsidiaries. All inter-company accounts, transactions, and profits have been eliminated in consolidation.

Segment information

Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker (“CODM”), or decision-making group, in deciding how to allocate resources and in assessing performance. The Company’s CODM consists of the chief executive officer, the chief financial officer, and the chief business officer. The Company views its operations and manages its business inone operating and reporting segment: life science. The life science segment is focused on the discovery, development and commercialization of the Company’s clinically differentiated medicines that provide benefits to patients with rare disorders. The Company is managed on a consolidated basis, and accordingly, the CODM assesses performance for the life science segment based on net income (loss), with a focus on revenues, research and development expense, and selling general, and administrative expense. Net income (loss) is reported on the income statement as consolidated net income (loss). The measure of segment assets is reported on the balance sheet as total consolidated assets. The Company derives its revenues through its worldwide net sales of its commercial products, collaboration agreements and license agreements, and royalty revenues. Refer to Note 15 for further segment information on revenues.

The Company expects to continue to incur significant expenses as it advances product candidates through all stages of development and clinical trials and, ultimately, seek regulatory approval. As such, the CODM uses cash forecast models in deciding how to invest into the life science segment. Such cash forecast models are reviewed to assess the entity-wide operating results and performance. Net income (loss) is used to monitor planned versus actual results. Monitoring planned versus actual results is used in assessing performance of the segment and in establishing management’s compensation, along with the cash forecast models. Refer to Note 15 for segment information on significant segment expenses and geographic breakdown.

Cash equivalents

The Company considers all highly liquid investments with a maturity of 90 days or less at the time of purchase to be cash equivalents. Cash equivalents are carried at cost which approximates fair value due to their short-term nature.

Marketable securities

The Company’s marketable securities consists of both debt securities and equity investments. The Company considers its investments in debt securities with original maturities of greater than 90 days to be available for sale securities. Securities under this classification are recorded at fair value and unrealized gains and losses within accumulated other comprehensive income (loss). The estimated fair value of the available for sale securities is determined based on quoted market prices or rates for similar instruments. In addition, the cost of debt securities in this category is adjusted for amortization of premium and accretion of discount to maturity. For available for sale debt securities in an unrealized loss position, the Company assesses whether it intends to sell or if it is more likely than not that the Company will be required to sell the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the security’s amortized cost basis is written down to fair value. If the criteria are not met, the Company evaluates whether the decline in fair value has resulted from a credit loss or other factors. In making this assessment, management considers, among other factors, the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency, and adverse conditions specifically related to the security. If this assessment

indicates that a credit loss exists, the present value of cash flows expected to be collected from the security are compared to the amortized cost basis of the security. If the present value of the cash flows expected to be collected is less than the amortized cost basis, a credit loss exists and an allowance for credit losses is recorded for the credit loss, limited by the amount that the fair value is less than the amortized costs basis. Any impairment that has not been recorded through an allowance for credit losses is recognized in other comprehensive income. For the years ended December 31, 2025 and 2024, no allowance was recorded for credit losses.

Marketable securities that are equity investments are measured at fair value, as it is readily available, and as such are classified as Level 1 assets. Unrealized holding gains and losses for these equity investments are components of other (expense) income, net within the consolidated statement of operations.

Concentration of credit risk

The Company’s financial instruments that are exposed to credit risks consist primarily of cash and cash equivalents, available-for-sale marketable securities and accounts receivable. The Company maintains its cash and cash equivalents in bank accounts, which, at times, exceed federally insured limits. The Company has not experienced any credit losses in these accounts and does not believe it is exposed to any significant credit risk on these funds. The Company’s investment policy includes guidelines on the quality of the financial institutions and financial instruments the Company is allowed to invest in, which the Company believes minimizes the exposure to concentration of credit risk.

The Company is subject to credit risk from its accounts receivable related to its product sales. The payment terms are predetermined and the Company evaluates the creditworthiness of each customer or distributor on a regular basis. The Company reserves all uninsured amounts billed directly to a patient until the time of cash receipt as collectability is not reasonably assured at the time the product is received. To date, the Company has not incurred any material credit losses.

Fixed assets

Fixed assets are stated at cost. Depreciation is computed starting when the asset is placed into service on a straight-line basis over the estimated useful life of the related asset as follows:

Inventory and cost of product sales

Inventory

Inventories are stated at the lower of cost and net realizable value, utilizing standard costing, which approximates average costs by product. The Company capitalizes inventory costs associated with products following regulatory approval when future commercialization is considered probable and the future economic benefit is expected to be realized. Products which may be used in clinical development programs are included in inventory and charged to research and development expense when the product enters the research and development process and no longer can be used for commercial purposes. Inventory used for marketing efforts are charged to selling, general and administrative expense. Amounts related to clinical development programs and marketing efforts are immaterial.

The following table summarizes the components of the Company’s inventory for the periods indicated:

The Company periodically reviews its inventories for excess amounts or obsolescence and writes down obsolete or otherwise unmarketable inventory to its estimated net realizable value. The Company recorded write downs of $5.2 million and $13.2 million for the years ended December 31, 2025 and 2024, respectively, primarily related to adjustments to inventory reserves and product approaching expiration. Additionally, though the Company’s product is subject to strict quality control and monitoring which it performs throughout the manufacturing processes, certain batches or units of product may not meet quality specifications resulting in a charge to cost of product sales. For the years ended December 31, 2025 and December 31, 2024, these amounts were immaterial.

Cost of product, collaboration and license sales

Cost of product, collaboration and license sales consists of the cost of inventory sold, manufacturing and supply chain costs, storage costs, amortization of the acquired intangible asset, royalty payments associated with net product sales, royalty payments to collaborative partners associated with royalty revenues and collaboration revenue related to milestones, and costs related to performance of services associated with license agreement revenues. Production costs are expensed as cost of product, collaboration and license sales when the related products are sold or royalty revenues and collaboration revenue milestones are earned.

Accumulated other comprehensive income (loss)

Accumulated other comprehensive income (loss) consists of unrealized gains or losses on marketable securities and foreign currency translation adjustments.

Revenue recognition

Net product revenue

The Company’s net product revenue primarily consists of sales of Translarna in territories outside of the U.S. for the treatment of nmDMD and sales of Emflaza in the U.S. for the treatment of DMD. Beginning in the second half of 2025, net product revenues also includes Sephience for the treatment of PKU. The Company recognizes revenue when its performance obligations with its customers have been satisfied. The Company’s performance obligations are to provide products based on customer orders from distributors, hospitals, specialty pharmacies or retail pharmacies. The performance obligations are satisfied at a point in time when the Company’s customer obtains control of the product, which is typically upon delivery. The Company invoices its customers after the products have been delivered and invoice payments are generally due within 30 to 90 days of the invoice date. The Company determines the transaction price based on fixed consideration in its contractual agreements. Contract liabilities arise in certain circumstances when consideration is due for goods the Company has yet to provide. As the Company has identified only one distinct performance obligation, the transaction price is allocated entirely to product sales. In determining the transaction price, a significant financing component does not exist since the timing from when the Company delivers product to when the customers pay for the

product is typically less than one year. Customers in certain countries pay in advance of product delivery. In those instances, payment and delivery typically occur in the same month.

The Company records product sales net of any variable consideration, which includes discounts, allowances, rebates related to Medicaid and other government pricing programs, and distribution fees. The Company uses the expected value or most likely amount method when estimating its variable consideration, unless discount or rebate terms are specified within contracts. The identified variable consideration is recorded as a reduction of revenue at the time revenues from product sales are recognized. These estimates for variable consideration are adjusted to reflect known changes in factors and may impact such estimates in the quarter those changes are known. Revenue recognized does not include amounts of variable consideration that are constrained.

In relation to customer contracts, the Company incurs costs to fulfill a contract but does not incur costs to obtain a contract. These costs to fulfill a contract do not meet the criteria for capitalization and are expensed as incurred. The Company considers any shipping and handling costs that are incurred after the customer has obtained control of the product as a cost to fulfill a promise. Shipping and handling costs associated with finished goods delivered to customers are recorded as a selling expense.

Collaboration, license, and royalty revenue

The terms of these agreements typically include payments to the Company of one or more of the following: nonrefundable, upfront license fees; milestone payments; research funding and royalties on future product sales. In addition, the Company generates service revenue through agreements that generally provide for fees for research and development services and may include additional payments upon achievement of specified events.

At the inception of a collaboration arrangement, the Company needs to first evaluate if the arrangement meets the criteria in Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 808 “Collaborative Arrangements” to then determine if ASC Topic 606 is applicable by considering whether the collaborator meets the definition of a customer. If the criteria are met, the Company assesses the promises in the arrangement to identify distinct performance obligations.

For licenses of intellectual property, the Company assesses, at contract inception, whether the intellectual property is distinct from other performance obligations identified in the arrangement. If the licensing of intellectual property is determined to be distinct, revenue is recognized for nonrefundable, upfront license fees when the license is transferred to the customer and the customer can use and benefit from the license. If the licensing of intellectual property is determined not to be distinct, then the license will be bundled with other promises in the arrangement into one distinct performance obligation. The Company needs to determine if the bundled performance obligation is satisfied over time or at a point in time. If the Company concludes that the nonrefundable, upfront license fees will be recognized over time, the Company will need to assess the appropriate method of measuring proportional performance.

For milestone payments, the Company assesses, at contract inception, whether the development or sales-based milestones are considered probable of being achieved. If it is probable that a significant revenue reversal will occur, the Company will not record revenue until the uncertainty has been resolved. Milestone payments that are contingent upon regulatory approval are not considered probable of being achieved until the applicable regulatory approvals or other external conditions are obtained as such conditions are not within the Company’s control. If it is probable that a significant revenue reversal will not occur, the Company will estimate the milestone payments using the most likely amount method. The Company will re-assess the development and sales-based milestones each reporting period to determine the probability of achievement. The Company recognizes royalties from product sales at the later of when the related sales occur or when

the performance obligation to which the royalty has been allocated has been satisfied. If it is probable that a significant revenue reversal will not occur, the Company will estimate the royalty payments using the most likely amount method.

The Company recognizes revenue for reimbursements of research and development costs under collaboration agreements as the services are performed. The Company records these reimbursements as revenue and not as a reduction of research and development expenses as the Company has the risks and rewards as the principal in the research and development activities.

Translarna France

During the year ended December 31, 2025, the Company changed its estimates for its sales allowance related to Translarna revenues in France, primarily based on its recent communications with the French pricing authorities subsequent to the EC’s adoption of the opinion of the CHMP of the EMA to not renew the authorization of Translarna for the treatment of nmDMD. This change in estimate resulted in an increase of $98.6 million to the sales allowance reserve, which is recorded within the accounts payable and accrued expenses line on the consolidated balance sheets for the period ended December 31, 2025, and a decrease to net product revenues of $98.6 million, which is recorded to the Translarna France line item on the consolidated statement of operations for the year ended December 31, 2025. The $98.6 million change in sales allowance estimate represents a life to date adjustment for the historical sales of Translarna in France. Translarna France revenues were reclassified from net product revenues to the Translarna France line item on the consolidated statement of operations for the years ended December 31, 2024 and December 31, 2023 to allow revenue for Translarna France to be comparable.

Allowance for doubtful accounts

The Company maintains an allowance for estimated losses resulting from the inability of its customers to make required payments. The Company estimates uncollectible amounts based upon current customer receivable balances, the age of customer receivable balances, the customer’s financial condition and current economic trends. The Company also assesses whether an allowance for expected credit losses may be required which includes a review of the Company’s receivables portfolio, which are pooled on a customer basis or country basis. In making its assessment of whether an allowance for credit losses is required, the Company considers its historical experience with customers, current balances, levels of delinquency, regulatory and legal environments, and other relevant current and future forecasted economic conditions. For the years ended December 31, 2025 and 2024, no allowance was recorded for credit losses. The allowance for doubtful accounts was $15.2 million as of December 31, 2025 and $2.3 million as of December 31, 2024. For the years ended December 31, 2025, 2024 and 2023, bad debt expense was $12.2 million, $1.7 million, and $0.9 million, respectively.

Liability for sale of future royalties

The Company has a royalty purchase agreement with Royalty Pharma Investments 2019 ICAV (“Royalty Pharma”) in which the Company sold its right to receive sales-based royalty payments on worldwide net sales of Evrysdi in exchange for upfront cash consideration from Royalty Pharma. In accordance with the guidance in ASC 470-10-25-2, the Company determined that cash consideration obtained pursuant to the royalty purchase agreement should be classified as debt and is recorded as “liability for sale of future royalties-current” and “liability for sale of future royalties-noncurrent” on the Company’s consolidated balance sheet based on the timing of the expected payments to be made to Royalty Pharma. The liability is amortized using the effective interest method over the life of the arrangement, in accordance with the respective guidance, utilizing the prospective method to account for subsequent changes in the estimated future payments to be made

to Royalty Pharma and the Company updates the effective interest rate on a quarterly basis. Refer to Note 7 for further details.

Leases

The Company determines if an arrangement is a lease at inception. This determination generally depends on whether the arrangement conveys to the Company the right to control the use of an explicitly or implicitly identified fixed asset for a period of time in exchange for consideration. Control of an underlying asset is conveyed to the Company if the Company obtains the rights to direct the use of and to obtain substantially all of the economic benefits from using the underlying asset. The Company has lease agreements which include lease and non-lease components, which the Company accounts for as a single lease component for all leases. Operating and finance leases are classified as right of use ("ROU") assets, short term lease liabilities, and long term lease liabilities. Operating and finance lease ROU assets and lease liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. ROU assets areamortized and lease liabilities accrete to yield straight-line expense over the term of the lease. Lease payments included in the measurement of the lease liability are comprised of fixed payments.

Variable lease payments associated with the Company’s leases are recognized when the event, activity, or circumstance in the lease agreement on which those payments are assessed occurs. Variable lease payments are presented in the Company’s consolidated statements of operations in the same line item as expense arising from fixed lease payments for operating leases.

Leases with an initial term of 12 months or less are not recorded on the consolidated balance sheet and the Company recognizes lease expense for these leases on a straight-line basis over the lease term. The Company applies this policy to all underlying asset categories.

A lessee is required to discount its unpaid lease payments using the interest rate implicit in the lease or, if that rate cannot be readily determined, its incremental borrowing rate. As most of the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The Company gives consideration to its recent debt issuances as well as publicly available data for instruments with similar characteristics when calculating its incremental borrowing rates.

The lease term for all of the Company’s leases includes the non-cancellable period of the lease plus any additional periods covered by either a Company option to extend (or not to terminate) the lease that the Company is reasonably certain to exercise, or an option to extend (or not to terminate) the lease controlled by the lessor. Leasehold improvements are capitalized and depreciated over the lesser of useful life or lease term. See Note 5, Leases for additional information.

Research and development costs

Research and development expenses include the clinical development costs associated with the Company’s product development programs and research and development costs associated with the Company’s discovery programs. These expenses include internal research and development costs and the costs of research and development conducted on behalf of the Company by third parties, including sponsored university-based research agreements and clinical study vendors. All research and development costs are expensed as incurred. Costs incurred in obtaining technology licenses are charged immediately to research and development expense if the technology licensed has not reached technological feasibility and has no alternative future uses.

Advance payments made for goods and services that will be used in future research and development activities are deferred if the contracted party has not yet performed the related activities. The amount deferred is then expensed when the research and development activities are performed. As of December 31, 2025 and 2024, the short term deferred research and development advance payments were $8.8 million and $7.4 million, respectively, and are classified as prepaid expenses and other current assets on the consolidated balance sheet. As of December 31, 2025 and 2024, the long term deferred research and development advance payments were $1.1 million and $1.7 million, respectively, and are classified as deposits and other assets on the consolidated balance sheet.

Fair value of financial instruments

The Company follows the fair value measurement rules, which provides guidance on the use of fair value in accounting and disclosure for assets and liabilities when such accounting and disclosure is called for by other accounting literature. These rules establish a fair value hierarchy for inputs to be used to measure fair value of financial assets and liabilities. This hierarchy prioritizes the inputs to valuation techniques used to measure fair value into three levels: Level 1 (highest priority), Level 2, and Level 3 (lowest priority).

Cash equivalents, marketable securities, and equity investments are reflected in the accompanying financial statements at fair value. The carrying amounts of receivables and accounts payable and accrued expenses approximate fair value due to the short-term nature of those instruments.

Share-based compensation

The Company measures the cost of employee services received in exchange for an award of equity instruments based on the grant date fair value of the award. Restricted stock awards are measured based on the fair market values of the underlying stock on the dates of grant. For service type awards, share-based compensation expense is recognized on a straight-line basis over the period during which the employee is required to provide service in exchange for the entire award.

The fair value of options is calculated using the Black-Scholes option pricing model to determine the fair value of stock options on the date of grant based on key assumptions such as expected volatility and expected term. The Company estimates the expected volatility of options utilizing the Company’s historical stock volatility. The Company estimates the expected term of options utilizing the Company’s historical exercise data. The risk-free rate of the option is based on U.S. Government Securities Treasury Constant Maturities yields at the date of grant for a term similar to the expected term of

the option. In connection with the adoption of FASB Accounting Standards Update (“ASU”) 2016-9, the Company made a policy election to continue its methodology for estimating its forfeiture rate.

Stock-based compensation expense for performance stock units (“PSUs”) is determined using the grant date fair value, which is the quoted closing market price per share of the Company’s common stock on the Nasdaq Global Select Market on the grant date. Stock-based compensation expense for the PSUs will not be recognized until the achievement of the performance goal is deemed probable (the “Probable Date”), a determination that requires significant judgment by management, as the achievement of these goals have inherent risk and uncertainties. At the Probable Date, the Company records a cumulative catch-up expense for the portion of the grant date fair value attributable to the period from the grant date to the Probable Date. The remaining expense is recognized over the remaining service period on a straight-line basis.

Stock-based compensation expense for market-based performance stock units vest only upon the satisfaction of market-based conditions. The market-based conditions are satisfied upon our achievement of specified stock prices and total shareholder return (“TSR”) compared to the group of companies in the Nasdaq Biotechnology Index (the “NBI”). For market-based awards, the Company determines the grant-date fair value utilizing a Monte Carlo valuation model, which incorporates various assumptions including expected stock price volatility, expected term, and risk-free interest rates. The Company estimates the volatility on the date of grant based on the Company’s and companies within the NBI’s historical stock volatilities, as applicable. The risk-free interest rate is based on the U.S. Treasury yield curve on the valuation date. The Company records stock-based compensation expense for the PSUs with market conditions on an accelerated attribution method over the requisite service period.

Income taxes

On December 15, 2022, the European Union (EU) member states formally adopted the EU’s Pillar Two Directive, which generally provides for a minimum effective tax rate of 15%, as established by the Organization for Economic Co-operation and Development (OECD) Pillar Two Framework that was supported by over 130 countries worldwide. The EU effective dates are January 1, 2024, and January 1, 2025, for different aspects of the directive. A significant number of other countries are also implementing similar legislation. As a result, the tax laws in the U.S. and other countries in which PTC and its affiliates do business could change on a prospective or retroactive basis and any such changes could materially adversely affect the Company’s business. The Company is continuing to evaluate the potential impact on future periods of the Pillar Two Framework, pending legislative adoption by additional individual countries, including those within the EU.

On December 22, 2017, the U.S. government enacted the 2017 Tax Cuts and Jobs Act (“TCJA”), which significantly revised U.S. tax law by, among other provisions, lowering the U.S. federal statutory income tax rate to 21%, imposing a mandatory one-time transition tax on previously deferred foreign earnings, and eliminating or reducing certain income tax deductions. The Global Intangible Low-tax Income ("GILTI") provisions of the TCJA require the Company to include in its U.S. income tax return foreign subsidiary earnings in excess of an allowable return on the foreign subsidiary’s tangible assets. The Company has elected to account for GILTI tax in the period in which it is incurred, and therefore has not provided any deferred tax impacts of GILTI in its consolidated financial statements for the period ended December 31, 2025.

Since 2022, TCJA amendments to IRC Section 174 have no longer permitted an immediate deduction for research and development (R&D) expenditures in the tax year that such costs are incurred. Instead, these IRC Section 174 development costs have had to be capitalized and amortized over either a five- or 15-year period for domestic and foreign expenditures, respectively. On July 4, 2025, the U.S. government enacted the One Big Beautiful Bill Act (“OBBBA”) which generally extended the tax provisions previously enacted by the TCJA that were set to expire, as well as made other

changes to federal tax law for multinational corporations. Effective beginning with PTC’s 2025 tax year, the OBBBA restored immediate deductibility of domestic expenditures, while foreign expenditures will continue to be capitalized and amortized over 15 years. Additionally, IRC Section 174A, enacted as part of the OBBBA, allows for the immediate expensing of all remaining unamortized domestic costs either upfront in 2025, or ratably in 2025 and 2026.

Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and net operating loss and credit carryforwards. Deferred tax assets and liabilities are measured at rates expected to apply to taxable income in the years in which those temporary differences and carryforwards are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the statement of operations in the period that includes the enactment date. A valuation allowance is recorded when it is not more likely than not that all or a portion of the net deferred tax assets will be realized.

Foreign currency

The functional currencies of the Company’s foreign subsidiaries primarily are the local currencies of the country in which the subsidiary operates. The Company’s asset and liability accounts are translated using the current exchange rate as of the balance sheet date. Stockholders’ equity accounts are translated using historical rates at the balance sheet date. Revenue and expense accounts are translated using a weighted average exchange rate over the period ended on the balance sheet date. Adjustments resulting from the translation of the financial statements of the Company’s foreign subsidiaries into U.S. dollars are accumulated as a separate component of stockholders’ equity within other comprehensive income. Gains or losses resulting from transactions denominated in foreign currencies are included in other income or expense, within the consolidated statements of operations.

Net income (loss) per share

Basic net income (loss) per share is calculated by dividing the net income (loss) attributable to common stockholders by the weighted average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net income per share is calculated by dividing the net income attributable to common stockholders by the weighted-average number of common share equivalents outstanding for the period determined using the treasury-stock method and the if-converted method. During periods in which the Company incurs net losses, both basic and diluted loss per share is calculated by dividing the net loss by the weighted average shares outstanding—potentially dilutive securities are excluded from the calculation because their effect would be anti-dilutive. Dilutive common stock equivalents are comprised of options and unvested restricted stock outstanding under the Company’s stock option plans.

Business combinations and asset acquisitions

The Company evaluates acquisitions of assets and other similar transactions to assess whether or not the transaction should be accounted for as a business combination or asset acquisition by first applying a screen to determine if substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or group of similar identifiable assets. If the screen is met, the transaction is accounted for as an asset acquisition. If the screen is not met, further determination is required as to whether or not the Company has acquired inputs and processes that have the ability to create outputs, which would meet the requirements of a business. If determined to be a business combination, the Company accounts for the transaction under the acquisition method of accounting as indicated in ASU 2017-01, “Business Combinations”, which requires the acquiring entity in a business combination to recognize the fair value of all assets acquired, liabilities assumed, and any non-controlling interest in the acquiree and establishes the acquisition date as the fair value measurement point. Accordingly, the Company recognizes assets acquired and liabilities assumed in business

combinations, including contingent assets and liabilities, and non-controlling interest in the acquiree based on the fair value estimates as of the date of acquisition. In accordance with ASC 805, the Company recognizes and measures goodwill as of the acquisition date, as the excess of the fair value of the consideration paid over the fair value of the identified net assets acquired.

The consideration for the Company’s business acquisitions may include future payments that are contingent upon the occurrence of a particular event or events. The obligations for such contingent consideration payments are recorded at fair value on the acquisition date. The contingent consideration obligations are then evaluated each reporting period. Changes in the fair value of contingent consideration, other than changes due to payments, are recognized as a gain or loss and recorded within the change in the fair value of contingent consideration in the consolidated statements of operations.

If determined to be an asset acquisition, the Company accounts for the transaction under ASC 805-50, which requires the acquiring entity in an asset acquisition to recognize assets acquired and liabilities assumed based on the cost to the acquiring entity on a relative fair value basis, which includes transaction costs in addition to consideration given. No gain or loss is recognized as of the date of acquisition unless the fair value of non-cash assets given as consideration differs from the assets’ carrying amounts on the acquiring entity’s books. Consideration transferred that is noncash will be measured based on either the cost (which will be measured based on the fair value of the consideration given) or the fair value of the assets acquired and liabilities assumed, whichever is more reliably measurable. Goodwill is not recognized in an asset acquisition and any excess consideration transferred over the fair value of the net assets acquired is allocated to the identifiable assets based on relative fair values.

Contingent consideration payments in asset acquisitions are recognized when the contingency is resolved and the consideration is paid or becomes payable (unless the contingent consideration meets the definition of a derivative, in which case the amount becomes part of the basis in the asset acquired). Upon recognition of the contingent consideration payment, the amount is included in the cost of the acquired asset or group of assets.

Finite-lived intangible assets

The Company records the fair value of purchased intangible assets with finite useful lives as of the transaction date of a business combination or asset acquisition. Purchased intangible assets with finite useful lives are amortized to their estimated residual values over their estimated useful lives.

Impairment of long-lived assets

The Company monitors its long-lived assets and finite-lived intangibles for indicators of impairment. If such indicators are present, the Company assesses the recoverability of affected assets by determining whether the carrying value of such assets is less than the sum of the undiscounted future cash flows of the assets. If such assets are found not to be recoverable, the Company measures the amount of such impairment by comparing the carrying value of the assets to the fair value of the assets, with the fair value generally determined based on the present value of the expected future cash flows associated with the assets.

Tangible asset impairment and (gains) losses on transactions, net

Tangible asset impairment and (gains) losses on transactions, net includes impairments identified on fixed assets, losses on sales of fixed assets, and gains on lease modifications and lease terminations. For the year ended December 31, 2025, these amounts consisted of a $10.8 million gain on the MassBio lease modification (Note 5). This amount was partially offset by a loss of $1.0 million in fixed asset impairments in connection with the Company’s office

relocations and closures, as well as a $0.1 million loss related to the sale of fixed assets. For the year ended December 31 2024, these amounts consisted of a $4.4 million loss primarily related to the sale of certain assets for gene therapy manufacturing, and a $4.1 million loss primarily related to fixed asset impairments in connection with the South Plainfield, New Jersey office closure and Warren, New Jersey lease modification. These amounts were partially offset by a gain of $2.2 million on lease terminations, and a gain of $5.5 million on lease modification.

Goodwill

Goodwill represents the amount of consideration paid in excess of the fair value of net assets acquired as a result of the Company’s business acquisitions accounted for using the acquisition method of accounting. Goodwill is not amortized and is subject to impairment testing at a reporting unit level on an annual basis or when a triggering event occurs that may indicate the carrying value of the goodwill is impaired. The Company reassesses its reporting units as part of its annual segment review. As of December 31, 2025, the Company concluded that it continues to operate asone reporting unit. An entity is permitted to first assess qualitative factors to determine if a quantitative impairment test is necessary. Further testing is only required if the entity determines, based on the qualitative assessment, that it is more likely than not that the fair value of the reporting unit is less than its carrying amount. The Company performed an annual test for goodwill as of October 1, 2025. The Company’s single reporting unit had a negative carrying value, and thus the Company determined there wasno impairment of goodwill.

Recent accounting pronouncements

In November 2024, the FASB issued ASU 2024-03, Income Statement-Reporting Comprehensive Income- Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses. ASU 2024-03 enhances financial reporting by requiring additional information about specific expense categories in the notes to financial statements at interim and annual reporting periods. The guidance is effective for public business entities for annual periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. Early adoption is permitted. The Company is currently planning to adopt this guidance when effective. The Company is assessing the impact of the adoption on the Company’s consolidated financial statements and accompanying footnotes but expects the impact will be enhanced disclosures related to income statement expenses.

In July 2025, the FASB issued ASU 2025-05, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets. ASU 2025-05 addresses challenges encountered when applying the guidance in Topic 326, Financial Instruments—Credit Losses, to current accounts receivable and current contract assets arising from transactions accounted for under Topic 606, Revenue from Contracts with Customers. The guidance is effective for public business entities for annual periods beginning after December 15, 2025, and interim reporting periods within those annual reporting periods. Early adoption is permitted in both interim and annual reporting periods in which financial statements have not yet been issued or made available for issuance. In developing reasonable and supportable forecasts as part of estimating expected credit losses, the guidance provides that all entities may elect a practical expedient that assumes that current conditions as of the balance sheet date do not change for the remaining life of the asset. The Company is currently planning to adopt this guidance when effective. The Company is assessing the impact of the adoption on the Company’s consolidated financial statements and accompanying footnotes but expects the guidance will not have a material impact.

In September 2025, the FASB issued ASU 2025-06, Intangibles—Goodwill and Other— Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software. ASU 2025-06 enhances accounting for software costs that are accounted for under Subtopic 350-40, Intangibles—Goodwill and Other—Internal-Use Software (referred to as “internal-use software”). The guidance is effective for public business entities for annual

periods beginning after December 15, 2027, and interim reporting periods within those annual reporting periods. Entities have three transition options: prospective, retrospective, or modified prospective adoption. Early adoption is permitted as of the beginning of an annual reporting period. Instead of following prescriptive project stages for capitalization of internal-use software, entities will capitalize costs when management has authorized and committed funding for the software project and it is probable that the project will be completed and used as intended. The Company is currently planning to adopt this guidance when effective. The Company is assessing the impact of the adoption on the Company’s consolidated financial statements and accompanying footnotes.

In December 2025, the FASB issued ASU 2025-11, Interim Reporting (Topic 270): Narrow-Scope Improvements. ASU 2025-11 clarifies and reorganizes existing guidance related to interim financial reporting and disclosures. The guidance is effective for public business entities for interim reporting periods with annual reporting periods beginning after December 15, 2027. The Company is assessing the impact of the adoption on the Company’s consolidated financial statements and accompanying footnotes but expects the guidance will not have a material impact, as the guidance does not change the recognition or measurement of financial statement amounts.

In December 2025, the FASB issued ASU 2025-12, Codification Improvements. ASU 2025-12 makes targeted improvements to the FASB Accounting Standards Codification by clarifying language, correcting technical errors, and addressing unintended codification applications across various topics in the U.S. GAAP. The guidance is effective for public business entities for interim reporting periods with annual reporting periods beginning after December 15, 2026. The Company is assessing the impact of the adoption on the Company’s consolidated financial statements and accompanying footnotes but expects the guidance will not have a material impact, as the guidance does not change the recognition or measurement of financial statement amounts.

Impact of recently adopted accounting pronouncements

In December 2023, the FASB issued ASU 2023-09, Improvements to Income Tax Disclosures. ASU 2023-09 enhances the transparency about income tax information through improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid information. The guidance is effective for public business entities for annual periods beginning after December 15, 2024. For entities other than public business entities, the amendments are effective for annual periods beginning after December 15, 2025. Early adoption is permitted. The Company adopted this guidance prospectively for the year ended December 31, 2025 and has updated its disclosures within its footnotes herein to include the required additional tax disclosures.

3. Fair value of financial instruments and investments

The Company follows the fair value measurement rules, which provide guidance on the use of fair value in accounting and disclosure for assets and liabilities when such accounting and disclosure is called for by other accounting literature. Cash equivalents, marketable securities, and equity investments are reflected in the accompanying financial statements at fair value. The carrying amount of receivables and accounts payable and accrued expenses approximate fair value due to the short-term nature of those instruments.

The Company uses the market approach to measure fair value for its marketable securities. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets. The Company’s marketable securities are classified as Level 2 as they primarily utilize broker quotes in a nonactive market to value these securities.

The Company owned common stock in ClearPoint Neuro, Inc. (“ClearPoint”) (formerly MRI Interventions, Inc.), a publicly traded medical device company. The ClearPoint equity investments (collectively, the “ClearPoint Equity Investments”) represented financial instruments, and therefore, were recorded at fair value, which was readily determinable. As of December 31, 2025, the Company sold all of its ClearPoint Equity Investments. The ClearPoint Equity Investments were components of prepaids and other current assets as of December 31, 2024 on the consolidated balance sheet. The Company classified its equity investments in ClearPoint as a Level 1 asset within the fair value hierarchy, as the value was based on a quoted market price in an active market, which was not adjusted.

In January 2020, the Company purchased a $10.0 million convertible note from ClearPoint that was convertible into ClearPoint shares at a conversion rate of $6.00 per share at any point throughout the term of the loan, with a maturity date five years from the purchase date. In August 2024, the outstanding principal amount of the convertible note, together with any accrued and unpaid interest thereon, was repaid in full by ClearPoint and therefore the balance at December 31, 2024 was $0. The Company determined that the convertible note represented an available for sale debt security and the Company had elected to record it at fair value under ASC 825. The Company classified its ClearPoint convertible debt security as a Level 2 asset within the fair value hierarchy, as the value was based on inputs other than quoted prices that are observable. The fair value of the ClearPoint convertible debt security was determined at each reporting period by utilizing a Black-Scholes option pricing model, as well as a present value of expected cash flows from the debt security utilizing the risk free rate and the estimated credit spread as of the valuation date as the discount rate.

The Company has an investment in mutual funds that is denominated in foreign currency and is classified as marketable securities on the Company’s consolidated balance sheets. This equity investment is reported at fair value, as it is readily available, and as such is classified as a Level 1 asset. Unrealized holding gains and losses for this equity investment are included as components of interest expense, net within the consolidated statement of operations.

The table presented below is a summary of changes in the fair value for the Company’s marketable securities – equity investments, ClearPoint Equity Investments, and ClearPoint convertible debt security for the years ended December 31, 2025 and 2024:

Fair value of marketable securities that are classified as available for sale debt securities is based upon market prices using quoted prices in active markets for identical assets quoted on the last day of the period. In establishing the estimated fair value of the remaining available for sale debt securities, the Company used the fair value as determined by its investment advisors using observable inputs other than quoted prices.

The following represents the fair value using the hierarchy described in Note 2 for the Company’s financial assets and liabilities that are required to be measured at fair value on a recurring basis as of December 31, 2025 and 2024:

No transfers of assets between Level 1 and Level 2 of the fair value measurement hierarchy occurred during the years ended December 31, 2025 and 2024.

The following is a summary of marketable securities accounted for as available for sale debt securities at December 31, 2025 and 2024:

For available for sale debt securities in an unrealized loss position, the Company assesses whether it intends to sell or if it is more likely than not that the Company will be required to sell the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the security’s amortized cost basis is written down to fair value. For the years ended December 31, 2025 and 2024, no write downs occurred. The Company does not intend to sell the investments and it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized cost basis, which may be maturity. The Company also reviews its available for sale debt securities in an unrealized loss position and evaluates whether the decline in fair value has resulted from credit losses or other factors. This review is subjective, as it requires management to evaluate whether an event or change in circumstances has occurred in that period that may be related to credit issues. For the years ended December 31, 2025 and 2024, no allowance was recorded for credit losses. Unrealized gains and losses are reported as a component of accumulated other comprehensive income (loss) in stockholders’ deficit.

For the year ended December 31, 2025, realized gains from the sale of available for sale debt securities were immaterial. For the year ended December 31, 2024, the Company had $3.4 million of realized gains from the sale of available for sale debt securities. Realized gains and losses are reported as a component of interest expense, net in the consolidated statement of operations.

The unrealized losses and fair values of available for sale debt securities that have been in an unrealized loss position for a period of less than and greater than or equal to 12 months as of December 31, 2025 are as follows:

The unrealized losses and fair values of available for sale debt securities that have been in an unrealized loss position for a period of less than and greater than or equal to 12 months as of December 31, 2024 are as follows:

Available for sale debt securities on the balance sheet at December 31, 2025 and 2024 mature as follows:

The Company classifies all of its marketable securities as current as they are all either available for sale debt securities or equity investments and are available for current operations.

Convertible senior notes

In September 2019, the Company issued $287.5 million of 1.5% convertible senior notes due September 15, 2026 (the “2026 Convertible Notes”). The fair value of the 2026 Convertible Notes, which differs from their carrying values, is influenced by interest rates, the Company’s stock price and stock price volatility and is determined by prices for the 2026 Convertible Notes observed in market trading which are Level 2 inputs. The estimated fair value of the 2026 Convertible Notes at December 31, 2025 and December 31, 2024 was $424.5 million and $321.3 million, respectively.

Level 3 valuation

The contingent consideration payable is fair valued each reporting period with the change in fair value recorded as a gain or loss within the change in the fair value of contingent consideration on the consolidated statements of operations. During the first quarter of 2025, the probability of triggering the remaining contingent consideration was determined to be remote, and therefore the balance was written down tozero. The change in fair value of the contingent consideration for the year ended December 31, 2025 is $0.8 million and is recorded in the consolidated statement of operations. Refer to Note 14 for additional details.

4. Fixed assets

Fixed assets, net were as follows at December 31, 2025 and 2024:

Depreciation expense was approximately $14.2 million, $14.9 million, and $13.9 million for the years ended December 31, 2025, 2024, and 2023, respectively.

For the year ended December 31, 2025, in connection with the Company’s office relocations and closures, the Company recorded a $1.0 million loss related to fixed asset impairments. Additionally, the Company recorded a $0.1 million loss on sales of fixed assets. During the year end December 31, 2024, the Company recorded a $4.4 million loss primarily related to the sale of certain assets for gene therapy manufacturing. Additionally, in connection with the South Plainfield, New Jersey office closure, as well as the Warren, New Jersey lease modification, the Company recorded a $4.1 million loss primarily related to fixed assets impairments. Both the fixed asset loss on sales and fixed asset impairments are recorded on the Company’s consolidated statement of operations within tangible asset impairment and (gains) losses on transactions, net.

5. Leases

The Company’s principal office space is a facility located in Warren, New Jersey, which is approximately 180,000 square feet. The Company also leases laboratory space in Bridgewater, New Jersey and other locations throughout the United States and office space in various countries for international employees primarily through workspace providers. On August 1, 2025, the Company commenced a lease for office and laboratory space at a facility located in Mountainview, CA. The initial term of the lease istwelve years and nine months with an aggregate base rent of approximately$42.6 million. The Company recorded an operating lease ROU asset of$26.8 million and an operating lease ROU liability of$26.7 million as of the commencement date of the lease.

The Company also has a finance lease related to its commercial manufacturing agreement with MassBiologics of the University of Massachusetts Medical School (“MassBio”). In December 2025, the MassBio remaining lease term was effectively reduced to 24 months, which was accounted for as a lease modification in accordance with ASC 842-10-25-12. The ROU liability was remeasured using an incremental borrowing rate at the date of modification of 5.2%. As the difference between the present value of future payments and the face value of future payments was determined to be immaterial, the Company recorded the remeasured lease liability at face value. As there is no corresponding ROU asset, the modification resulted in a $10.8 million gain, which is included within tangible asset impairment and (gains) losses on transactions, net on the Company’s consolidated statements of operations for the year ended December 31, 2025. As of December 31, 2025, the balance of the finance lease liabilities-current and finance lease liabilities-non-current are $3.0 million and $3.0 million, respectively, and are directly related to the Company’s MassBio Agreement. As of

December 31, 2024, the balance of the finance lease liabilities-current and finance lease liabilities non-current were $3.0 million and $15.6 million, respectively. Additionally, during the years ended December 31, 2025 and December 31, 2024, the Company recorded finance lease costs of $1.3 million and $1.4 million, respectively, related to interest on the lease liability.

The Company also leases certain vehicles, lab equipment, and office equipment under operating leases. The Company’s operating leases have remaining lease terms ranging from 0.5 years to 13.4 years and certain leases include renewal options to extend the lease for up to 15 years. Rent expense was $21.1 million, $24.9 million, and $29.0 million for the years ended December 31, 2025, 2024 and 2023.

The components of lease expense were as follows:

Total operating lease cost is a component of operating expenses on the consolidated statements of operations.

Supplemental lease term and discount rate information related to leases was as follows:

Supplemental cash flow information related to leases was as follows:

Future minimum lease payments under non-cancelable leases as of December 31, 2025 were as follows:

6. Accounts payable and accrued expenses

Accounts payable and accrued expenses at December 31, 2025 and 2024 consist of the following:

7. Debt

Liability for sale of future royalties

On July 17, 2020, the Company, RPI Intermediate Finance Trust (“RPI”), and, for the limited purposes set forth in the agreement, Royalty Pharma PLC, entered into a royalty purchase agreement (the “Original Royalty Purchase Agreement”). Pursuant to the Original Royalty Purchase Agreement, the Company sold to RPI 42.933% (the “Original Assigned Royalty Rights”) of the Company’s right to receive sales-based royalty payments (the “Royalty”) on worldwide net sales of Evrysdi and any other product developed pursuant to the License and Collaboration Agreement (the “License Agreement”), dated as of November 23, 2011, by and among the Company, Roche and, for the limited purposes set forth therein, the SMA Foundation under the SMA program. In consideration for the sale of the Original Assigned Royalty Rights, RPI paid the Company$650.0 million in cash consideration. At the time, the Company retained a 57.067% interest in the Royalty and all economic rights to receive the remaining potential regulatory and sales milestone payments under the License Agreement, which remaining milestone payments equal$150.0 million in the aggregate as of December 31,

2025. The Original Royalty Purchase Agreement was set to terminate 60 days following the earlier of the date on which Roche is no longer obligated to make any payments of the Royalty pursuant to the License Agreement and the date on which RPI has received$1.3 billion in respect of the Original Assigned Royalty Rights.

Pursuant to the guidance in ASC 470-10-25-2, the Company determined that the $650.0 million cash consideration obtained pursuant to the Original Royalty Purchase Agreement should be classified as debt and recorded it as “liability for sale of future royalties-current” and “liability for sale of future royalties-noncurrent” on the Company’s consolidated balance sheet based on the timing of the expected payments to be made to RPI at the time of the transaction. The liability was subsequently amortized using the effective interest method over the life of the arrangement, in accordance with the respective guidance, utilizing the prospective method to account for subsequent changes in the estimated future payments to be made to RPI.

On October 18, 2023, the Company, Royalty Pharma Investments 2019 ICAV (“Royalty Pharma”), and, for the limited purposes set forth in the agreement, Royalty Pharma plc, entered into an Amended and Restated Royalty Purchase Agreement (the “A&R Royalty Purchase Agreement”), which amends and restates in its entirety the Original Royalty Purchase Agreement. Pursuant to the A&R Royalty Purchase Agreement, the Company sold or agreed to sell to Royalty Pharma certain portions of the Company’s remaining Royalty on worldwide net sales of Evrysdi and any other product (the “Products”) developed pursuant to the SMA License Agreement (all such retained Royalty rights of the Company, the “Retained Royalty Rights,” and all such Royalty rights that are sold to Royalty Pharma pursuant to the A&R Royalty Purchase Agreement, the “A&R Assigned Royalty Rights”). At closing, Royalty Pharma paid the Company $1.0 billion in cash consideration for 38.0447% of the Company’s Retained Royalty Rights (which is in addition to the 42.9330% assigned to Royalty Pharma in connection with the Original Royalty Purchase Agreement, for a total of 80.9777% of the total Royalty) until such time as Royalty Pharma has received payments in respect of the Original Assigned Royalty Rights equal to $1.3 billion in the aggregate, and thereafter 66.6667% of the total Royalty. The A&R Royalty Purchase Agreement allowed the Company to sell to Royalty Pharma the remainder of the Company’s Retained Royalty Rights in exchange for an aggregate of $500.0 million in additional cash consideration after the closing of the A&R Royalty Purchase Agreement, less royalties received in respect of the Retained Royalty Rights put to Royalty Pharma, which would have been payable by Royalty Pharma pursuant tofive put options held by the Company that were exercisable at the Company’s option between January 1, 2024 and December 31, 2025. If the Company exercisedtwo or fewer of the put options, Royalty Pharma could have exercised a call option during the period from and after January 1, 2026 until and including March 31, 2026 for up to 50% of the remainder of the Company’s Retained Royalty Rights less amounts exercised by the Company via its put options at a purchase price that is proportional to the purchase price of the Company’s unexercised put options. Royalty Pharma’s exercise of the call option would have resulted in Royalty Pharma owning 90.4888% of the total Royalty until such time as Royalty Pharma had received payments in respect of the Original Assigned Royalty Rights equal to $1.3 billion in the aggregate, and thereafter 83.3333% of the total Royalty. The A&R Royalty Purchase Agreement was set to terminate 60 days following the date on which Roche was no longer obligated to make any payments of the Royalty pursuant to the SMA License Agreement.

The change in rights and obligations from the A&R Royalty Purchase Agreement resulted in a change in the terms of the liability for sale of future royalties, which was evaluated by the Company in accordance with ASC 470-50, Debt — Modifications and Extinguishments. The Company determined that the present value of the cash flows under the A&R Royalty Purchase Agreement were substantially different from the present value of the cash flows under the Original Royalty Purchase Agreement. This resulted in the derecognition of the old liability for sale of future royalties and the new liability for sale of future royalties being recorded at fair value, which was determined to be $1,809.9 million as of the date of the A&R Royalty Purchase Agreement. This resulted in an extinguishment loss of $44.9 million, which was recorded within loss on extinguishment of debt, within the Company’s statement of operations in the year ended December 31, 2023.

The fair value for the new liability for sale of future royalties on the date of the A&R Royalty Purchase Agreement was based on the Company’s estimates of future royalties expected to be paid to Royalty Pharma over the life of the arrangement, which was determined using forecasts from market data sources, which are considered Level 3 inputs. The liability is being amortized using the effective interest method over the life of the arrangement, in accordance with ASC 470 and ASC 835. The initial annual effective interest rate was determined to be 10.8%. The Company utilized the prospective method to account for subsequent changes in the estimated future payments to be made to Royalty Pharma and updated the effective interest rate on a quarterly basis. Issuance costs related to the transaction were determined to be immaterial.

In June 2024, the Company, Royalty Pharma and Royalty Pharma plc, entered into an amendment to the A&R Royalty Purchase Agreement. Under the A&R Royalty Purchase Agreement, the Company exercised a put option in June 2024, resulting in the Company receiving$241.8 million in cash consideration. In connection with the put option exercise, the change in rights and obligations resulted in a change in the terms of the liability for sale of future royalties, which was evaluated by the Company in accordance with ASC 470-50, Debt —Modifications and Extinguishments. The Company determined that the present value of the cash flows after the put option exercise was not substantially different and was therefore determined to be a modification. The$241.8 million in cash consideration obtained was added to the liability for sale of future royalties and the annual effective interest rate under the A&R Royalty Purchase Agreement was determined to be 9.9%. The liability was being amortized using the effective interest method over the life of the arrangement, in accordance with the respective guidance, utilizing the prospective method to account for subsequent changes in the estimated future payments to be made to Royalty Pharma and the Company updated the effective interest rate on a quarterly basis.

As a result of the option, the Company had sold to Royalty Pharma a total of 90.49% of the Royalty, which would have been reduced to 83.33% (the “Assigned Royalty Rights”) after Royalty Pharma receives$1.3 billion in aggregate payments (the “Assigned Royalty Cap”) from the Royalty assigned at the closing of the Original Purchase Agreement. The Company had retained 9.51% of the Royalty, which would have increased to 16.67% after the Assigned Royalty Cap had been met. The Company had the option under the A&R Royalty Purchase Agreement to sell its retained portions of the Royalty to Royalty Pharma in up tothree tranches for the following payments: (1)$100.0 million in exchange for 3.81% of the Royalty, which increased to 6.67% after the Assigned Royalty Cap had been met, (2)$100.0 million in exchange for 3.81% of the Royalty, which increased to 6.67% after the Assigned Royalty Cap had been met, and (3)$50.0 million in exchange for 1.90% of the Royalty, which increased to 3.33% after the Assigned Royalty Cap had been met, in each case less Royalty payments received by the Company with respect to the Assigned Royalty Rights.

In December 2025, the Company, Royalty Pharma and, for the limited purposes set forth in Amendment No. 2 (as defined below), Royalty Pharma plc, entered into an Amendment No. 2 to Amended and Restated Royalty Purchase Agreement (the “Amendment No. 2”), which amends that certain A&R Royalty Purchase Agreement, as amended. Under Amendment No. 2, the Company sold to Royalty Pharma a certain portion of the Company’s right to receive sales-based royalty payments on worldwide net sales of Roche’s Evrysdi*®* (risdiplam) product and any other product developed pursuant to the License and Collaboration Agreement, dated as of November 23, 2011, by and among the Company, F. Hoffman-La Roche Ltd, Hoffman-La Roche Inc. (together with F. Hoffman-La Roche Ltd, “Roche”), and, for the limited purposes set forth therein, the Spinal Muscular Atrophy Foundation (such payments, the “Royalty”). Pursuant to Amendment No. 2, on December 29, 2025, the Company sold to Royalty Pharma its retained interest in the Royalty in exchange for $240.0 million in upfront cash consideration, andthree potential additional purchase price payments of $20.0 million each conditioned upon receipt by Royalty Pharma of more than $347.0 million of Assigned Royalty Payments (as defined in the A&R Royalty Purchase Agreement) in respect of Calendar Year Net Sales (as defined in the A&R Royalty Purchase Agreement) arising in 2027, $363.0 million of Assigned Royalty Payments in respect of Calendar Year Net Sales

arising in 2028, and $379.0 million of Assigned Royalty Payments in respect of Calendar Year Net Sales arising in 2029, respectively. The retained interest sold by the Company to Royalty Pharma pursuant to the Amendment is equal to 9.5111% of the Royalty before the 2020 Assigned Royalty Cap (as defined in the A&R Royalty Purchase Agreement) has been met, and 16.6666% of the Royalty from and after such time as the 2020 Assigned Royalty Cap has been met. As a result of the sale, Royalty Pharma owns 100% of the Royalty and the Company owns 0% of the Royalty.

In connection with the receipt of the $240.0 million, the change in rights and obligations resulted in a change in the terms of the liability for sale of future royalties, which was evaluated by the Company in accordance with ASC 470-50, Debt —Modifications and Extinguishments. The Company determined that the present value of the cash flows after the Amendment No. 2 was not substantially different and was therefore determined to be a modification. The $240.0 million in cash consideration obtained was added to the liability for sale of future royalties and the annual effective interest rate under the A&R Royalty Purchase Agreement was determined to be 11.0%. The liability is being amortized using the effective interest method over the life of the arrangement, in accordance with the respective guidance, utilizing the prospective method to account for subsequent changes in the estimated future payments to be made to Royalty Pharma and the Company updates the effective interest rate on a quarterly basis.

The following table shows the activity within the “liability for sale of future royalties- current” and “liability for sale of future royalties- noncurrent” accounts for the year ended December 31, 2025:

Non-cash interest expense is recorded in the statement of operations within “Interest expense, net”.

2026 Convertible Notes

In September 2019, the Company issued, at par value, $287.5 million aggregate principal amount of 1.50% convertible senior notes due 2026, which included an option to purchase up to an additional $37.5 million in aggregate principal amount of the 2026 Convertible Notes, which was exercised in full by the initial purchasers. The 2026 Convertible Notes bear cash interest at a rate of 1.50% per year, payable semi-annually on March 15 and September 15 of each year, beginning on March 15, 2020. The 2026 Convertible Notes will mature on September 15, 2026, unless earlier repurchased or converted. The net proceeds to the Company from the offering were $279.3 million after deducting the initial purchasers’ discounts and commissions and the offering expenses payable by the Company.

The 2026 Convertible Notes are governed by an indenture (the “2026 Convertible Notes Indenture”) with U.S Bank National Association as trustee (the “2026 Convertible Notes Trustee”).

Holders of the 2026 Convertible Notes may convert their 2026 Convertible Notes at their option at any time prior to the close of business on the business day immediately preceding March 15, 2026 only under the following circumstances:

On or after March 15, 2026, until the close of business on the business day immediately preceding the maturity date, holders may convert their 2026 Convertible Notes at any time, regardless of the foregoing circumstances. Upon conversion, the Company will pay or deliver, as the case may be, cash, shares of the Company’s common stock or any combination thereof at the Company’s election.

The conversion rate for the 2026 Convertible Notes was initially, and remains,19.0404 shares of the Company’s common stock per $1,000 principal amount of the 2026 Convertible Notes, which is equivalent to an initial conversion price of approximately $52.52 per share of the Company’s common stock. The conversion rate may be subject to adjustment in some events but will not be adjusted for any accrued and unpaid interest. As of December 31, 2025, the 2026 Convertibles Notes are convertible.

The Company was not permitted to redeem the 2026 Convertible Notes prior to September 20, 2023. The Company may redeem for cash all or any portion of the 2026 Convertible Notes, at its option, if the last reported sale price of its common stock has been at least 130% of the conversion price then in effect on the last trading day of, and for at least 19 other trading days (whether or not consecutive) during, any 30 consecutive trading day period ending on, and including, the trading day immediately preceding the date on which the Company provides notice of redemption, at a redemption price equal to 100% of the principal amount of the 2026 Convertible Notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. No sinking fund is provided for the 2026 Convertible Notes, which means that the Company is not required to redeem or retire the 2026 Convertible Notes periodically. As of December 31, 2025, the 2026 Convertible Notes are redeemable.

If the Company undergoes a “fundamental change” (as defined in the 2026 Convertible Notes Indenture), subject to certain conditions, holders of the 2026 Convertible Notes may require the Company to repurchase for cash all or part of their 2026 Convertible Notes at a repurchase price equal to 100% of the principal amount of the 2026 Convertible Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date.

The 2026 Convertible Notes represent senior unsecured obligations and will rank senior in right of payment to the Company’s future indebtedness that is expressly subordinated in right of payment to the notes, equal in right of payment to the Company’s existing and future unsecured indebtedness that is not so subordinated, effectively junior in right of payment to any of the Company’s secured indebtedness to the extent of the value of the assets securing such indebtedness, and structurally subordinated to all existing and future indebtedness and other liabilities (including trade payables) incurred by the Company’s subsidiaries. The 2026 Convertible Notes Indenture contains customary events of default with respect to the 2026 Convertible Notes, including that upon certain events of default (including the Company’s failure to make any payment of principal or interest on the 2026 Convertible Notes when due and payable) occurring and continuing, the 2026 Convertible Notes Trustee by notice to the Company, or the holders of at least 25% in principal amount of the outstanding 2026 Convertible Notes by notice to the Company and the Convertible Notes Trustee, may, and the 2026 Convertible Notes Trustee at the request of such holders (subject to the provisions of the 2026 Convertible Notes Indenture) will, declare 100% of the principal of and accrued and unpaid interest, if any, on all the 2026 Convertible Notes to be due and payable. In case of certain events of bankruptcy, insolvency or reorganization, involving the Company or a significant subsidiary,100% of the principal of and accrued and unpaid interest on the 2026 Convertible Notes will automatically become due and payable. Upon such a declaration of acceleration, such principal and accrued and unpaid interest, if any, will be due and payable immediately.

The 2026 Convertible Notes consist of the following:

As of December 31, 2025, the remaining contractual life of the 2026 Convertible Notes is approximately 0.7 years.

The following table sets forth total interest expense recognized related to the 2026 Convertible Notes:

8. Capital structure

Common stock

In August 2019, the Company entered into an At the Market Offering Sales Agreement (the “Sales Agreement”) with Cantor Fitzgerald and RBC Capital Markets, LLC (together, the “Sales Agents”), pursuant to which, the Company may offer and sell shares of its common stock, having an aggregate offering price of up to $125.0 million from time to time through the Sales Agents by any method that is deemed to be an “at the market offering” as defined in

Rule 415(a)(4) promulgated under the Securities Act of 1933, as amended. No shares were sold pursuant to the Sales Agreement during the years ended December 31, 2025, 2024, and 2023. The remaining shares of the Company’s common stock available to be issued and sold, under the Sales Agreement, have an aggregate offering price of up to $93.0 million as of December 31, 2025.

In February 2023, the Company completed enrollment of its Phase 3 placebo-controlled clinical trial for sepiapterin for PKU. In connection with this event and pursuant to the Censa Merger Agreement, the Company paid a $30.0 million development milestone to the former Censa securityholders during the year ended December 31, 2023. The Company elected to pay this milestone in the form of shares of its common stock, less certain cash payments in accordance with the Censa Merger Agreement. Pursuant to such election, the Company issued 657,462 shares of its common stock and paid $0.4 million to the former Censa securityholders.

As of December 31, 2025, the Company’s number of authorized shares of common stock was 250,000,000.

9. Net income (loss) per share

Basic and diluted net income (loss) per share is computed by dividing net income (loss) by the weighted-average number of common shares outstanding.

The following table sets forth the computation of basic and diluted net income (loss) per share for common stockholders:

The following table shows historical common shares outstanding, which are not included in the above historical calculation, as the effect of their inclusion is anti-dilutive during each period. The anti-dilutive shares are calculated as the unweighted outstanding shares as of the reporting period end date that are antidilutive using the treasury stock method.

For the years ended December 31, 2024 and 2023 all stock options and unvested restricted stock units were anti-dilutive because the Company experienced a net loss.

10. Stock award plan

In May 2013, the Company’s Board of Directors and stockholders approved the 2013 Long Term Incentive Plan, which became effective upon the closing of the Company’s IPO. The 2013 Long Term Incentive Plan provides for the grant of incentive stock options, nonstatutory stock options, restricted stock awards and other stock-based awards. On June 8, 2022 (the “Restatement Effective Date”), the Company’s stockholders approved the Amended and Restated 2013 Long-Term Incentive Plan (the “Amended 2013 LTIP”). The Amended 2013 LTIP provides for the grant of incentive stock options, nonstatutory stock options, restricted stock units and other stock-based awards. The number of shares of common stock reserved for issuance under the Amended 2013 LTIP is the sum of (A) the number of shares of the Company’s common stock (up to 16,724,212 shares) that is equal to the sum of (1) the number of shares issued under the 2013 Long-Term Incentive Plan prior to the Restatement Effective Date, (2) the number of shares that remain available for issuance under the 2013 Long-Term Incentive Plan immediately prior to the Restatement Effective Date and (3) the number of shares subject to awards granted under the 2013 Long-Term Incentive Plan prior to the Restatement Effective Date that are outstanding as of the Restatement Effective Date, plus (B) from and after the Restatement Effective Date, an additional 8,475,000 shares of Common Stock. As of December 31, 2025, awards for 5,270,151 shares of common stock were available for issuance under the Amended 2013 LTIP.

There areno additional shares of common stock available for issuance under the Company’s 1998 Employee, Director and Consultant Stock Option Plan, 2009 Equity and Long Term Incentive Plan or 2013 Stock Incentive Plan.

In January 2020, the Company’s Board of Directors approved the 2020 Inducement Stock Incentive Plan. The 2020 Inducement Stock Incentive Plan provides for the grant of incentive stock options, nonstatutory stock options, restricted stock awards and other stock-based awards, initially up to an aggregate of 1,000,000 shares of common stock. Any grants made under the 2020 Inducement Stock Incentive Plan must be made pursuant to the Nasdaq Listing Rule 5635(c)(4) inducement grant exception as a material component of the Company’s new hires’ employment compensation. In December 2020, the Company’s Board of Directors approved an additional 1,000,000 shares of common stock that may be issued under the 2020 Inducement Stock Incentive Plan. In April 2022, the Company’s Board of Directors approved a reduction in the total number of shares of common stock that may be issued under the 2020 Inducement Stock Incentive Plan to 1,300,000 shares. In December 2022, the Company’s Board of Directors approved an additional 1,700,000 shares of common stock that may be issued under the 2020 Inducement Stock Inventive Plan. As of December 31, 2025, awards for 1,791,985 shares of common stock are available for issuance under the 2020 Inducement Stock Incentive Plan.

The Board of Directors has the authority to select the individuals to whom options are granted and determine the terms of each option, including (i) the number of shares of common stock subject to the option; (ii) the date on which the option becomes exercisable; (iii) the option exercise price, which, in the case of incentive stock options, must be at least 100% (110% in the case of incentive stock options granted to a stockholder owning in excess of 10% of the Company’s stock)

of the fair market value of the common stock as of the date of grant; and (iv) the duration of the option (which, in the case of incentive stock options, may not exceedten years). Options typically vest over afour-year period.

Inducement stock option awards

Pursuant to the Nasdaq inducement grant exception, during the year ended December 31, 2025, the Company issued options to purchase an aggregate of 59,025 shares of common stock to certain new hire employees at a weighted-average exercise price of $57.97 per share under the 2020 Inducement Stock Incentive Plan. Additionally, during the year ended December 31, 2025, the Company issued 121,625 restricted stock units under the 2020 Inducement Stock Incentive Plan. An aggregate of 173,351 options and 20,168 restricted stock units previously granted as inducement awards were forfeited during the year ended December 31, 2025 in connection with employee separations from the Company.

Stock option activity—A summary of stock option activity is as follows:

The fair values of grants made in the years ended December 31, 2025, 2024 and 2023 were contemporaneously estimated on the date of grant using the following assumptions:

The Company assumedno expected dividends for all grants. The weighted average grant date fair value of options granted during the years ended December 31, 2025, 2024 and 2023 was $25.57, $14.04, and $21.27 per share, respectively.

Restricted Stock Units—Restricted stock units are granted subject to certain restrictions, including in some cases service conditions (restricted stock). The grant-date fair value of restricted stock units, which has been determined based upon the market value of the Company’s shares on the grant date, is expensed over the vesting period.

The following table summarizes information on the Company’s restricted stock units:

Performance-based Restricted Stock Units—In December 2023, the Company granted 150,000 performance-based restricted stock units (“PSUs”) to its Chief Executive Officer, Dr. Matthew Klein, which will vest only if challenging performance goals relating to development and regulatory milestones are achieved over an approximatelytwo year performance period. In December 2024, the Company granted 25,000 performance-based restricted stock units to Dr. Klein, which will vest only if challenging performance goals relating to development, regulatory, or commercial goals are achieved over an approximately five year performance period and granted an additional 31,250 PSUs, which will vest only if challenging performance goals relating to stock price goals are achieved over an approximately five year performance period. In December 2025, the Company granted 100,000 PSUs to Dr. Klein, and the number of PSUs that vest shall be determined based upon the Company’s total shareholder return (“TSR”) over the period beginning on November 14, 2025 and ending on December 31, 2028 relative to the TSR on the Measurement Date of the group of companies in the Nasdaq Biotechnology Index (the “NBI”). Together, the PSUs with stock price goals and the PSUs related to the TSR are considered the “PSUs with market conditions”.

During the period ended December 31, 2025, the performance conditions for 75,000 of these PSUs granted to Dr. Klein in December 2023 were satisfied due to the Company’s achievement of a regulatory milestone and are included in the restricted stock units table above. The expense related to these PSUs was $1.1 million for the period ending December 31, 2025. During the period ended December 31, 2025,75,000 PSUs with performance conditions were forfeited due to the regulatory performance conditions not being satisfied before the service period end date. The achievement of the remaining performance goals for the PSU’s granted to Dr. Klein has not yet been deemed probable and therefore, no expense has been recognized to date. During the period ending December 31, 2025, the market conditions for 15,625 of these PSUs granted to Dr. Klein in December 2024 were satisfied due to the Company’s achievement of stock price value and are included in the restricted stock units table above. The expense related to these PSUs was $0.4 million for the period ending December 31, 2025. The expense related to the total PSUs with market conditions was $0.6 million for the period ending December 31, 2025.

The following table summarizes information on the Company’s PSUs:

Employee Stock Purchase Plan—In June 2016, the Company established an Employee Stock Purchase Plan (as amended, “ESPP” or the “Plan”) for certain eligible employees. The Plan is administered by the Company’s Board of Directors or a committee appointed by the Board. In June 2021, the Plan was amended to increase the total number of shares available for purchase under the Plan fromone million shares totwo million shares of the Company’s common stock. Employees may participate over asix-month period through payroll withholdings and may purchase, at the end of thesix-month period, the Company’s common stock at a purchase price of at least 85% of the closing price of a share of the Company’s common stock on the first business day of the offering period or the closing price of a share of the Company’s common stock on the last business day of the offering period, whichever is lower. No participant will be granted a right to purchase the Company’s common stock under the Plan if such participant would own more than 5% of the total combined voting power of the Company or any subsidiary of the Company after such purchase. For the period ending December 31, 2025, the Company recorded $2.2 million in compensation expense related to the ESPP.

The Company recorded share-based compensation expense in the statement of operations related to incentive stock options, nonstatutory stock options, restricted stock units and the ESPP as follows:

As of December 31, 2025, there was approximately $129.8 million of total unrecognized compensation cost related to unvested share-based compensation arrangements granted under the Company’s Plans. This cost is expected to be recognized as compensation expense over the weighted average remaining service period of approximately 2.6 years.

11. Other comprehensive income (loss) and accumulated other comprehensive items

Other comprehensive income (loss) includes changes in equity that are excluded from net income (loss), such as unrealized gains and losses on marketable securities.

The following table summarizes other comprehensive income (loss) and the changes in accumulated other comprehensive items, by component, for the years ended December 31, 2025, 2024, and 2023, respectively.

Reclassified amounts from other comprehensive items were determined using the actual realized gains and losses from the sales of marketable securities.

12. Revenue recognition

Net product sales

The Company views its operations and manages its business inone operating segment: life science.

During the years ended December 31, 2025, 2024, and 2023, net product revenues consisted of the following:

Disaggregated net product revenues by country for the years ended December 31, 2025, 2024, and 2023 are as follows:

Net product revenue for sales of Translarna in France are not depicted in the net product revenue tables above. Refer to Note 2 for further details.

For the year ended December 31, 2025, four of the Company’s distributors each accounted for over 10% of the Company’s net product sales. For the years ended December 31, 2024 and 2023, two of the Company’s distributors each accounted for over 10% of the Company’s net product sales.

As of December 31, 2025 and 2024, the Company does not have a contract liabilities balance related to net product sales and has not made significant changes to the judgments made in applying ASC Topic 606.

Collaboration and License revenue

In November 2011, the Company and the SMA Foundation entered into a licensing and collaboration agreement with Roche. Under the terms of the SMA License Agreement, Roche acquired an exclusive worldwide license to the Company’s SMA program.

Under the agreement, the Company is eligible to receive additional payments from Roche if specified events are achieved with respect to each licensed product, including up to $135.0 million in research and development event milestones, up to $325.0 million in sales milestones upon achievement of certain sales events, and up to double digit royalties on worldwide annual net sales of a commercial product.

For the years ended December 31, 2025 and 2024 collaboration revenue related to the SMA License Agreement with Roche was immaterial. For the year ended December 31, 2023, the Company recognized collaboration revenue related to the SMA License Agreement with Roche of $100.0 million. The below summarizes the milestone achievements associated with the Company’s SMA program during the years ended December 31, 2025, 2024 and 2023.

The SMA program currently hasone approved product, Evrysdi, which was approved in August 2020 by the FDA for the treatment of SMA in adults and children two months and older. For the year ended December 31, 2023, the Company recognized a sales milestone of $100.0 million for the achievement of $1.5 billion in worldwide annual net sales from Evrysdi. The remaining potential sales milestone as of December 31, 2025 is $150.0 million upon achievement of certain sales events. As of December 31, 2025, the Company doesnot have any remaining research and development milestones that can be received.

In addition to research and development and sales milestones, the Company is eligible to recognize royalties on worldwide annual net sales of a commercial product under the SMA License Agreement. For the years ended December 31, 2025, 2024 and 2023 the Company has recognized $244.2 million, $203.9 million, and $168.9 million of royalty revenue related to Evrysdi, respectively.

In November 2024, the Company entered into the Novartis Agreement with Novartis related to the Company’s votoplam HD program. The transaction contemplated by the Novartis Agreement closed in January 2025. Under the Novartis Agreement, and upon the closing of the transaction, the Company received an upfront nonrefundable payment of $1.0 billion on the effective date and can receive up to $1.9 billion in development, regulatory and sales milestones, a 40% share of U.S. profits and losses, and tiered double-digit royalties on ex-U.S. sales.

The Company evaluated the Novartis Agreement in order to determine the proper accounting treatment and concluded that the arrangement was not subject to ASC 730 or ASC 808, as the upfront payment was nonrefundable with no obligation for the Company to repay it and as the Company is not exposed to significant risks. The Company evaluated the arrangement under ASC 606, as a contract with a customer was determined to exist.

Pursuant to the Novartis Agreement, the Company was required to transfer the applicable licenses and related manufacturing and other know how to Novartis and to complete the Phase 2A clinical trial and continue the ongoing open label extension (“OLE”) clinical trial of votoplam pursuant to its existing development plan, with the goal of transitioning the ongoing OLE clinical trial to Novartis within 12 months after the effective date of the Novartis Agreement. As of December 31, 2025, these performance obligations were completed. Novartis will be responsible for all other development of licensed compounds and licensed products and the manufacture and commercialization of licensed compounds and licensed products worldwide. Therefore, the Company determined that there were three material and distinct performance obligations: the transfer of the licenses and know-how, completion of the Phase 2A clinical trial, and continuing the OLE clinical trial until transitioned to Novartis. As of December 31, 2025, all performance obligations were completed.

The Company determined that the transaction included the fixed consideration of the $1.0 billion and variable consideration in the form of milestones, profit share, and royalties. Management evaluated the variable consideration under ASC 606 and determined that it would be fully constrained until the contingencies were resolved or any applicable sales occurred. Management allocated the transaction price of $1.0 billion to the performance obligations based on the guidance in ASC 606.

During the year ended December 31, 2025, the Company recognized $1.0 billion in license revenues related to Novartis. For the years ended December 31, 2024 and 2023, the Company didnot recognize license revenue related to Novartis. As all performance obligations are complete, there isno remaining deferred revenue related to the Novartis Agreement on the consolidated balance sheet as of December 31, 2025. Collaboration and license revenue during the year ended December 31, 2025 was partially offset by $3.5 million related to a refund for a prior collaboration arrangement in relation to votoplam.

Manufacturing Revenue

For the year ended December 31, 2025, the Company didnot recognize manufacturing revenue. For the years ended December 31, 2024 and 2023, the Company recognized $1.7 million and $7.7 million of manufacturing revenue, respectively, related to the production of DNA and AAV vectors for gene therapy applications for external customers. The Company has not made significant changes to the judgments made in applying ASC Topic 606 for the years ended 2025, 2024, and 2023.

As of December 31, 2025 and 2024, the Company didnot have contract liabilities balances related to the production of plasmid DNA and AAV vectors for gene therapy applications for external customers. For the year ended December 31, 2024, the Company recognized $0.8 million related to the amounts included in the contract liability balance at the beginning of the period.

As of December 31, 2025 and 2024, the Company hasno contract assets related to plasmid DNA and AAV production for external customers.

In June 2024, the Company sold its gene therapy manufacturing business in Hopewell Township, New Jersey. Accordingly, the Company does not expect to have manufacturing revenue going forward. There areno remaining performance obligations as of December 31, 2025 and 2024.

13. Income taxes

The income (loss) from operations before tax (expense) benefit consisted of the following for the years ended December 31, 2025, 2024, and 2023:

The Income Tax Provision consisted of the following for the years ended December 31, 2025, 2024 and 2023:

The difference between income tax expense and effective tax rate and the amounts resulting from applying the federal statutory rate of 21% to Income before income taxes in 2025 after the adoption of ASU 2023-09 is as follows:

1 State taxes in Illinois made up the majority (greater than 50%) of the tax effect of this category

A reconciliation of the provision for income taxes to the amount computed by applying the 21% statutory U.S. federal income tax rate to income before income taxes for years prior to the adoption of ASU 2023-09 is as follows:

Accounting for income taxes under U.S. GAAP requires that individual tax-paying entities of the company offset all deferred tax liabilities and assets within each particular tax jurisdiction and present them as a noncurrent deferred tax liability or asset. Amounts in different tax jurisdictions cannot be offset against each other. The Company did not have any amounts related to deferred income taxes.

The significant components of the Company’s deferred tax assets and liabilities at December 31, 2025 and 2024 are as follows:

For the year ended December 31, 2025, the Company generated taxable income in the U.S. of $277.8 million. The Company has recorded a current federal income tax provision expense of $14.2 million and a current state income tax provision expense of $4.7 million which are driven by the income related to the Novartis Agreement.

At December 31, 2025 and 2024, the Company recorded a valuation allowance against its net deferred tax assets of $816.5 million and $857.6 million, respectively. The change in the valuation allowance during the years ended December 31, 2025 and 2024 was $41.1 million and $23.8 million, respectively. A valuation allowance has been recorded since, in the judgment of management, these assets are not more likely than not to be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during periods in which those temporary differences and carryforwards become deductible or are utilized. As of December 31, 2025, the Company had $13.0 million, and $43.9 million of state and foreign net operating loss carryforwards, respectively. The Company utilized its remaining federal net operating loss carryforwards in the 2024 tax year and no carryforwards to the current year to offset taxable income.

As of December 31, 2025, the combined Research and Development and Orphan Drug Credit carryforward for federal purposes is $164.6 million.

The income tax (expense) benefit for the year ended December 31, 2025 differed from the amounts computed by applying the U.S. federal income tax rate of 21% to income before tax expense as a result of nontaxable dividend income related to the Translarna IP transfer, the deduction of unamortized domestic section 174 capitalized costs following the

enactment of the One Big Beautiful Bill Act, US tax effects of foreign items, including “global intangible low-taxed income” (“GILTI”), tax credits generated, and a decrease in the Company’s valuation allowance.

The income tax (expense) benefit for the years ended December 31, 2024 and 2023 differed from the amounts computed by applying the U.S. federal income tax rate of 21% to loss before tax expense as a result of the recognition of royalty income for income tax purposes related to the A&R Royalty Purchase Agreement, foreign taxes, section 174 capitalized costs prior to the One Big Beautiful Bill Act, the impact of permanent differences, including “global intangible low-taxed income” (“GILTI”), tax credits generated, true up of net operating loss carryforwards, and increase in the Company’s valuation allowance.

Under the 2017 Tax Cuts and Jobs Act, the ability to currently deduct qualifying research and experimental costs under section 174, as well as software development costs, are eliminated for tax years beginning after December 31, 2021. Under the new rule, these costs must be capitalized and amortized over a five-year or fifteen-year period, depending on whether the research is conducted in the U.S. or abroad, respectively. The rule became effective for the Company during the 2022 tax year. On July 4, 2025, the One Big Beautiful Bill Act (the “OBBBA”) was enacted into law. The OBBBA includes changes to U.S. tax law that were applicable to the Company beginning in tax year 2025, with additional provisions applying in subsequent years. Included in these changes are favorable adjustments to deductions for qualified property and research and development expenditures which were previously capitalized under the Tax Cuts and Jobs Act, as well as reforms to the international tax framework.

The Company applies the elements of FASB ASC 740-10 regarding accounting for uncertainty in income taxes. This clarifies the accounting for uncertainty in income taxes recognized in financial statements and required impact of a tax position to be recognized in the financial statements if that position is more likely than not of being sustained by the taxing authority. As of December 31, 2025, the Company recorded unrecognized tax benefits in the amount of $15.1 million including interest and penalties through 2025. The Company’s policy is to recognize interest and penalties related to tax matters within the income tax provision. Tax years beginning in 2014 are generally subject to examination by taxing authorities, although net operating losses from all years are subject to examinations and adjustments for at least three years following the year in which the attributes are used. The Company is currently under a corporate business tax audit in New Jersey for tax years 2020 through 2022. Although the outcome of tax audits is always uncertain, the company does not expect any adjustment to result for these years as of December 31, 2025.

For all years through December 31, 2016, the Company generated research credits but has not conducted a study to document the qualified activities. This study may result in an adjustment to the Company’s research and development credit carryforwards; however, until a study is completed and any adjustment is known, no amounts are being presented as an uncertain tax position. A full valuation allowance has been provided against the Company’s research and development credits and, if an adjustment is required, this adjustment would be offset by an adjustment to the deferred tax asset established for the research and development credit carryforwards and the valuation allowance.

As a result of U.S. tax reform legislation, distributions of profits from non-U.S. subsidiaries are not expected to cause a significant incremental U.S. tax impact in the future. However, distributions may be subject to non-U.S. withholding taxes if profits are distributed from certain jurisdictions. As of December 31, 2025, for purposes of ASC 740-10-25-3, the Company had $654.3 million of undistributed earnings from non-U.S. subsidiaries that it intends to reinvest permanently in its non-U.S. operations. As these ASC 740-10-25-3 earnings are considered permanently reinvested, no tax provision has been accrued. It is not feasible to estimate the amount of tax that might be payable on the eventual remittance of such earnings.

Unrecognized Tax Benefits

A reconciliation of the gross amount of unrecognized tax benefits, excluding accrued interest and penalties, is as follows:

Uncertain tax positions, for which management's assessment is that there is a more than 50% probability of sustaining the position upon challenge by a taxing authority based upon its technical merits, are subject to certain recognition and measurement criteria. The nature of the uncertain tax positions is often very complex and subject to change, and the amounts at issue can be substantial. The Company develops its cumulative probability assessment of the measurement of uncertain tax positions using internal experience, judgment, and assistance from professional advisors. The Company re-evaluates these uncertain tax positions on a quarterly basis based on a number of factors including, but not limited to, changes in facts or circumstances, changes in tax law, and effectively settled issues under audit and new audit activity. Any change in these factors could result in the recognition of a tax benefit or an additional charge to the tax provision.

The Company records penalties and tax-related interest expense on unrecognized tax benefits as a component of the provision for income taxes in the accompanying consolidated statement of operations. The Company has recorded interest related to uncertain tax positions for the year ended December 31, 2025, in the accompanying consolidated balance sheet. Future changes in the Company’s unrecognized tax benefits will affect the Company’s annual effective tax rate.

14. Commitments and contingencies

Under various agreements, the Company will be required to pay royalties and milestone payments upon the successful development and commercialization of products.

Pursuant to the Agilis Merger Agreement with Agilis, Agilis equityholders were previously entitled to receive contingent consideration payments from the Company based on (i) the achievement of certain development milestones up to an aggregate maximum amount of $60.0 million, (ii) the achievement of certain regulatory approval milestones together with a milestone payment following the receipt of a priority review voucher up to an aggregate maximum amount of $535.0 million, (iii) the achievement of certain net sales milestones up to an aggregate maximum amount of $150.0 million, and (iv) a percentage of annual net sales for FA and Angelman syndrome during specified terms, ranging from 2%-6%. The Company was required to pay $40.0 million of the development milestone payments upon the passing of the second anniversary of the closing of the Agilis Merger, regardless of whether the applicable milestones have been achieved.

As of December 31, 2025, all of the milestones have either been paid or settled, with the exception of the regulatory milestones and net sales milestones related to FA and Angelman syndrome and the net sales milestones related to Upstaza/Kebilidi. In May 2023, as part of the Company’s strategic portfolio prioritization, the Company decided to discontinue its preclinical and early research programs in its gene therapy platform, which included FA and Angelman syndrome. As a result, the Company does not expect the milestones related to FA and Angelman syndrome to be achieved. In addition, the Company does not expect to pay the 2%–6% royalties on annual net sales related to FA and Angelman syndrome. As of December 31, 2025, the remaining potential sales milestones related to Upstaza/Kebilidi are up to $50.0 million, however the Company has determined that the probability of triggering these milestones is remote.

On October 25, 2019, the Company completed the acquisition of substantially all of the assets of BioElectron Technology Corporation (“BioElectron”), a Delaware corporation, including certain compounds that the Company has begun to develop as part of its Bio-e platform, pursuant to an asset purchase agreement by and between the Company and BioElectron, dated October 1, 2019 (the “BioElectron Asset Purchase Agreement”). BioElectron was a private company with a pipeline focused on inflammatory and central nervous system (CNS) disorders. The lead program, vatiquinone, is in late stage development for CNS disorders with substantial unmet need and significant commercial opportunity that are complementary to PTC’s existing pipeline.

Subject to the terms and conditions of the BioElectron Asset Purchase Agreement, BioElectron may become entitled to receive contingent milestone payments of up to $200.0 million (in cash or in shares of the Company’s common stock, as determined by the Company) from the Company based on the achievement of certain regulatory and net sales milestones. Subject to the terms and conditions of the BioElectron Asset Purchase Agreement, BioElectron may also become entitled to receive contingent payments based on a percentage of net sales of certain products.

Subject to the terms and conditions of the Agreement and Plan of Merger, dated as of May 5, 2020 (the “Censa Merger Agreement”) by and among the Company, Hydro Merger Sub, Inc., the Company’s wholly owned, indirect subsidiary, and, solely in its capacity as the representative, agent and attorney-in-fact of the securityholders of Censa, Shareholder Representative Services LLC (such merger pursuant thereto, the “Censa Merger”), former Censa securityholders may become entitled to receive contingent payments from the Company based on (i) the achievement of certain development and regulatory milestones up to an aggregate maximum amount of $217.5 million for sepiapterin’s two most advanced programs and receipt of a priority review voucher from the FDA as set forth in the Censa Merger Agreement, (ii) $109.0 million in development and regulatory milestones for each additional indication of sepiapterin, (iii) the achievement of certain net sales milestones up to an aggregate maximum amount of $160.0 million, (iv) a percentage of annual net sales during specified terms, ranging from single to low double digits of the applicable net sales threshold amount, and (v) any sublicense fees paid to the Company in consideration of any sublicense of Censa’s intellectual property to commercialize sepiapterin, on a country-by-country basis, which contingent payment shall equal to a mid-double digit percentage of any such sublicense fees.

In February 2023, the Company completed enrollment of its Phase 3 placebo-controlled clinical trial for sepiapterin for PKU. In connection with this event and pursuant to the Censa Merger Agreement, the Company paid a $30.0 million development milestone to the former Censa securityholders during the year ended December 31, 2023. The Company elected to pay this milestone in the form of shares of its common stock, less certain cash payments in accordance with the Censa Merger Agreement. Pursuant to such election, the Company issued 657,462 shares of its common stock and paid $0.4 million to the former Censa securityholders.

In May 2024, the Company announced the validation and acceptance for review of an MMA for sepiapterin by the EMA for the treatment of PKU. Pursuant to the Censa Merger Agreement, the acceptance triggered a $15.0 million regulatory milestone payment to the former Censa securityholders. In July 2024, the Company announced the submission of an NDA to the FDA for sepiapterin for the treatment of pediatric and adult patients with PKU, including the full spectrum of ages and disease subtypes. Pursuant to the Censa Merger Agreement, the decision to submit the NDA triggered a $25.0 million regulatory milestone payment to the former Censa securityholders. In September 2024, the Company announced the FDA acceptance for filing of the NDA. Pursuant to the Censa Merger Agreement, the acceptance triggered a $25.0 million regulatory milestone payment to the former Censa securityholders. Together, the $65.0 million of regulatory milestones were paid and recorded within research and development expense on the Company’s consolidated statements of operations for the year ended December 31, 2024.

On August 5, 2025, the Company, certain former securityholders of Censa, and, for the limited purposes set forth in the agreement, Shareholder Representative Services LLC, entered into a Rights Satisfaction Agreement (the “Rights Satisfaction Agreement”) pursuant to which such former securityholders of Censa (the “Participating Rightsholders”) agreed to the cancellation and forfeiture of their rights to receive certain contingent payments from the Company based on worldwide annual net sales by the Company of products containing sepiapterin (“Net Sales of Product”) under the Censa Merger Agreement in exchange for the consideration set forth in the Rights Satisfaction Agreement and further detailed below.

Pursuant to the terms of the Rights Satisfaction Agreement, the Participating Rightsholders canceled and forfeited their rights under the Censa Merger Agreement to receive a percentage of annual net sales during the applicable payment term equal to (i)8% of annual Net Sales of Product for that portion of annual Net Sales of Product less than or equal to $250.0 million, (ii)10% of annual Net Sales of Product for that portion of annual Net Sales of Product greater than $250.0 million but less than $500.0 million and (iii)12% of annual Net Sales of Product for that portion of annual Net Sales of Product greater than $500.0 million (collectively, the “Net Sales Payments”).

In consideration of the foregoing, the Company agreed to pay to the Participating Rightsholders an aggregate amount in cash up to $250.0 million (the “Upfront Consideration”) upon the consummation of the transactions contemplated by the Rights Satisfaction Agreement and potential milestone payments (each an “Additional Milestone Payment”) of up to $100.0 million each (or up to $500.0 million in the aggregate) based on the achievement of specified Net Sales Thresholds (as defined in the Censa Merger Agreement). The amount of the Upfront Consideration and the Additional Milestone Payments was subject to adjustment in the Rights Satisfaction Agreement based on the number of Participating Rightsholders.

At the consummation of the transactions contemplated by the Rights Satisfaction Agreement, based on the participation of former Censa securityholders holding approximately 90% of Censa’s equity securities prior to the consummation of the transactions contemplated by the Censa Merger Agreement, the Company paid an aggregate amount of Upfront Consideration in cash of $225.1 million, which was recorded as an intangible asset and is being amortized to cost of product sales over its expected useful life on a straight-line basis. Additionally, the Company is obligated to make Additional Milestone Payments in an amount equal to approximately $90.0 million upon achievement of each of the (i) first occurrence of athree or fewer consecutive calendar year period in which aggregate Net Sales of Product are greater than $3.0 billion, (ii) first occurrence of afive or fewer consecutive calendar year period in which aggregate Net Sales of Product are greater than $5.0 billion, (iii) first occurrence of aseven or fewer consecutive calendar year period in which aggregate Net Sales of Product are greater than $7.0 billion, (iv) first occurrence of anine or fewer consecutive calendar year period in which aggregate Net Sales of Product are greater than $9.0 billion and (v) first occurrence of an 11 or fewer consecutive calendar year period in which aggregate Net Sales of Product are greater than $11.0 billion. If, after the consummation of the transactions contemplated by the Rights Satisfaction Agreement, any additional former securityholder of Censa executes and delivers a joinder to the Rights Satisfaction Agreement and becomes a party thereto, the Company will pay such former securityholder an amount in cash equal to such former securityholder’s applicable pro rata share of the Upfront Consideration (less any Net Sale Payments previously received) and any Additional Milestone Payments that become payable to Participating Rightsholders under the Rights Satisfaction Agreement.

The Rights Satisfaction Agreement has no effect on the Censa Merger Agreement other than to provide for the cancellation and forfeiture of the Participating Rightsholders’ rights to receive the Net Sales Payments described above. As a result, all other rights and obligations under the Censa Merger Agreement remain in effect pursuant to their terms, including, without limitation, the Company’s obligation to pay certain contingent payments upon the achievement of certain development and Net Sales of Product milestones.

In June 2025, sepiapterin was granted marketing authorization by the EC for the treatment of children and adults living with PKU. Pursuant to the Censa Merger Agreement, the acceptance triggered a $25.0 million regulatory milestone payment to the former Censa securityholders. In July 2025, sepiapterin was granted FDA approval for the treatment of children and adults living with PKU. Pursuant to the Censa Merger Agreement, the approval triggered a $32.5 million milestone payment to the former Censa securityholders. As of December 31, 2025, these milestones were paid and recorded as intangible assets and are being amortized to cost of product sales over their expected useful lives on a straight-line basis. As of December 31, 2025, $152.5 million of the $217.5 million in development and regulatory milestones have been paid to the former Censa securityholders.

The Company also has the Tegsedi-Waylivra Agreement for the commercialization of Tegsedi and Waylivra, and products containing those compounds in countries in Latin America and the Caribbean. Akcea is entitled to receive royalty payments subject to certain terms set forth in the Tegsedi-Waylivra Agreement.

The Company has employment agreements with certain employees which require the funding of a specific level of payments, if certain events, such as a change in control or termination without cause, occur. Additionally, the Company has royalty payments associated with Translarna, Emflaza, Sephience, and Upstaza/ Kebilidi net product revenue, payable quarterly or annually in accordance with the terms of the related agreements.

From time to time in the ordinary course of its business, the Company is subject to claims, legal proceedings and disputes. The Company is not currently aware of any material legal proceedings against it.

15. Segment and geographic information

The Company views its operations and manages its business inone operating segment: life science. The table below summarizes the significant expense categories for the life science segment regularly reviewed by the CODM for the years ended December 31, 2025, 2024, and 2023:

The following table presents financial information based on the geographic location of the facilities of the Company as of and for the years ended:

16. 401(k) plan

The Company maintains a 401(k) plan for its employees. Employee contributions are voluntary. The Company may match employee contributions in amounts to be determined at the Company’s sole discretion. The Company provided a 100% matching contribution for up to the first 6% of each contributing employee’s base salary contributions for the years ended December 31, 2025, 2024 and 2023, respectively. The Company made matching contributions to the 401(k) plan and recorded expense of approximately $8.0 million, $7.3 million, and $10.9 million for the years ended December 31, 2025, 2024 and 2023, respectively.

17. Intangible assets and goodwill

Definite-lived intangibles

Definite lived intangible assets consisted of the following at December 31, 2025 and 2024:

Akcea is also entitled to receive royalty payments subject to certain terms set forth in the Tegsedi-Waylivra Agreement related to sales of Waylivra and Tegsedi. In accordance with the guidance for an asset acquisition, the Company records royalty payments when they become payable to Akcea and increase the cost basis for the Waylivra and Tegsedi intangible assets, respectively. For the year ended December 31, 2025, royalties of $4.1 million and $4.4 million for Tegsedi and Waylivra, respectively, were recorded on the consolidated balance sheet within intangible assets, net. As of December 31, 2025, a royalty payable of $0.4 million and $0.1 million for Tegsedi and Waylivra, respectively, was recorded on the consolidated balance sheet within accounts payable and accrued expenses.

Pursuant to the Rights Satisfaction Agreement, in August 2025, upfront cash consideration of $225.1 million was paid to the former Censa securityholders. The upfront cash consideration was recorded as an intangible asset and is being amortized to cost of product sales over its expected useful life on a straight-line basis. Pursuant to the Censa Merger Agreement, in June 2025, a $25.0 million milestone payment from the Company to the former Censa securityholders was triggered when the EC granted marketing authorization to Sephience for the treatment of children and adults living with PKU. Pursuant to the Censa Merger Agreement, in July 2025, a $32.5 million milestone payment from the Company to the former Censa securityholders was triggered when the FDA approved Sephience for the treatment of children and adults

living with PKU. These milestones were recorded as intangible assets and are being amortized to cost of product sales over their expected useful lives on a straight-line basis.

The former Censa securityholders may also be entitled to receive other contingent payments subject to certain terms set forth in the Censa Merger Agreement related to sales of Sephience. In accordance with the guidance for an asset acquisition, the Company will record such payments when they become payable to the former Censa securityholders and increase the cost basis for the Sephience intangible asset. For the year ended December 31, 2025, royalties of $0.9 million for Sephience was recorded on the consolidated balance sheet within intangible assets, net. As of December 31, 2025, a royalty payable of $0.9 million for Sephience was recorded on the consolidated balance sheet within accounts payable and accrued expenses.

For the years ended December 31, 2025, 2024 and 2023, the Company recognized amortization expense of $24.7 million, $60.7 million, and $222.6 million respectively, related to its intangible assets.

The estimated future amortization of the Company’s intangible assets is expected to be as follows:

Effective December 31, 2025, the Company changed its estimate for Upstaza and Kebilidi useful lives, primarily due to the decrease in lease term for MassBio, its commercial manufacturer for these products. The resulting change in future amortization is reflected in the table above. The weighted average remaining amortization period of the definite-lived intangibles as of December 31, 2025 is 11.0 years.

Indefinite-lived intangibles

In May 2023, as part of the Company’s strategic portfolio prioritization, the Company decided to discontinue its preclinical and early research programs in its gene therapy platform, which included programs for Friedreich ataxia and Angelman syndrome. As a result, the Company determined that its Friedreich ataxia and Angelman syndrome indefinite lived intangible assets were fully impaired and recorded impairment expense of$217.8 million which is recorded as intangible asset impairment in the statement of operations for the year ended December 31, 2023.

The Company also recorded intangible asset impairment for its PTC-AADC indefinite lived intangible asset of $159.5 million for the year ended December 31, 2024. The impairment was related to a decrease in projected cash flows due to refinements in current market assumptions and the timing of patient treatments. To calculate the impairment amount, the Company utilized a discounted cash flow model under the income method, which primarily utilized Level 3 fair value inputs. The discount rate utilized in the discounted cash flow model was 15%, and the probability of success was 100% as the Company received regulatory approval in Brazil and the United States. There areno remaining indefinite lived intangible assets on the consolidated balance sheets as of December 31, 2024 and 2025.

Goodwill

As a result of the Agilis Merger on August 23, 2018, the Company recorded $82.3 million of goodwill. There have beenno changes to the balance of goodwill since the date of the Agilis Merger. Accordingly, the goodwill balance as of December 31, 2025 and 2024 was $82.3 million. The Company performed an annual impairment test for goodwill as of October 1, 2025. The Company’s single reporting unit had a negative carrying value and thus the Company determined there wasno impairment of goodwill.

18. Subsequent events

The Company has evaluated all subsequent events and transactions through the filing date. There were no material events that impacted the audited consolidated financial statements or disclosures.