Item 7. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

The following discussion and analysis is intended to provide material information around events and uncertainties known to management that are relevant to an assessment of the financial condition and results of operations of X4 Pharmaceuticals and should therefore be read in conjunction with our audited Consolidated Financial Statements and the related notes thereto and other disclosures included as part of this Annual Report on Form 10-K, including the disclosures under Part I, Item 1A. Risk Factors.

Overview

We are a biopharmaceutical company developing, and commercializing novel therapeutics for the treatment of rare hematology diseases. We continue to progress our global, pivotal Phase 3 clinical trial, (the “4WARD” trial) to evaluate the efficacy, safety, and tolerability of oral, once-daily mavorixafor (with or without stable doses of granulocyte colony-stimulating factor (“G-CSF”) in people with congenital, acquired primary autoimmune, or idiopathic chronic neutropenia (“CN”) who are experiencing recurrent and/or serious infections. The 52-week trial is a randomized, double-blind, placebo-controlled, multicenter study aiming to enroll up to 176 patients, with full enrollment expected in the third quarter of 2026. The U.S. Food and Drug Administration (“FDA”) has granted Fast Track designation to mavorixafor for the treatment of CN, which is defined as periods lasting more than three months persistently or intermittently where there are abnormally low levels of neutrophils circulating in the blood, and may be idiopathic (of unknown origin), cyclic (episodes typically occurring every three weeks), or congenital (of genetic causation). CN disorders are rare blood conditions similarly characterized by increased risks of infections and cancer due to abnormally low levels of neutrophils in the body. In all cases, the CXCL12/CXCR4 pathway is the key regulator of neutrophil release from the bone marrow.

We have one commercially approved product, XOLREMDI ® (mavorixafor), which has received accelerated approval in the United States from the FDA for use as an oral, once-daily therapy in patients 12 years of age and older with WHIM (warts, hypogammaglobulinemia, infections, and myelokathexis) syndrome, to increase the number of circulating mature neutrophils and lymphocytes. WHIM syndrome is a rare combined primary immunodeficiency and CN disorder. In connection with our long term strategy to successfully complete the 4WARD Phase 3 trial in patients with moderate and severe CN, we are no longer prioritizing investment in the WHIM indication.

Private Placement Financing and Management Changes

During the third quarter of 2025, we sold shares of common stock and pre-funded warrants to purchase shares of common stock in a private placement that resulted in net proceeds of approximately $81.0 million, after deducting placement agent fees and other expenses. Pursuant to registration rights agreements, we registered the shares of common stock issued and issuable under pre-funded warrants under a registration statement on Form S-3 that was declared effective by the SEC on September 17, 2025.

Concurrent with the financing and effective August 12, 2025, our former President and Chief Executive Officer, Paula Ragan, PhD, and Chief Financial Officer, Adam Mostafa, stepped down from their respective roles and their employment was terminated. Dr. Ragan also resigned from the Company’s Board of Directors (the “Board”), and Michael Wyzga transitioned from Board Chair to Lead Independent Director. The Board appointed Adam R. Craig, M.D., Ph.D, MBA as Executive Chairman, John Volpone as President and subsequently as Chief Operating Officer, and David Kirske as Chief Financial Officer.

Q4 2025 Equity Financing

In October 2025, we closed an underwritten public offering of our common stock and, in lieu of common stock to certain investors, pre-funded warrants to purchase shares of common stock, raising net proceeds of $145.6 million, net of underwriting discounts and estimated offering expenses.

Strategic Restructurings

•In the first quarter of 2025, we implemented a strategic restructuring of our business operations, workforce and capital spending to focus efforts on advancing mavorixafor to treat patients with CN. As part of this restructuring, we (i) implemented a net reduction of our employee headcount by 43 employees, representing approximately 30% of our total workforce, including our U.S. commercial field team, (ii) commenced the closure of our research and development facility in Vienna, Austria, (iii) paused our pre-clinical drug candidate programs and (iv) streamlined other spending to support the ongoing clinical development of mavorixafor for the larger population of those with chronic neutropenia. We incurred charges of approximately $2.1 million for severance and other employee termination-related costs related to this strategic restructuring.

•In the third quarter 2025, we announced an additional strategic restructuring designed to further sharpen operational focus and align resources with our long‐term strategy to successfully complete the 4WARD Phase 3 trial in patients with moderate and severe CN. As part of this initiative, we further reduced our workforce by approximately 50%. We incurred expenses of approximately $4.9 million during the third quarter for severance and other employee termination-related costs related to this strategic restructuring. This workforce reduction was substantially completed in the third quarter of 2025.

These strategic restructuring actions have allowed us to decrease our operating expenses, including research and development and general and administrative expenses, from $143.2 million in 2024 to $116.2 million in 2025. The estimate of costs that we expect to incur related to these workforce reduction as well as the decrease in spending, and the timing thereof are subject to a number of assumptions and actual results may differ. We may also incur additional costs not currently contemplated due to events that may occur as a result of, or that are associated with, the actions described above.

Regulatory Update and Out-License Agreements

In early 2025, we submitted a Marketing Authorization Application (“MAA”) to the EMA seeking regulatory approval to commercialize mavorixafor for WHIM syndrome in the European Union. Such MAA was validated for processing by the EMA in January 2025. In February 2026, the EMA’s Committee for Medicinal Products for Human Use adopted a positive opinion recommending the grant of marketing authorization, under exceptional circumstances, for mavorixafor for the treatment of WHIM syndrome in the European Union. The positive opinion has been submitted to the European Commission for review, and we expect the European Commission to issue a final approval decision in the second quarter of 2026. On January 13, 2025, we announced a License and Supply Agreement (the “Norgine Agreement”) with Norgine Pharma UK (“Norgine”), pursuant to which Norgine was granted an exclusive license to distribute, market and sell our drug product for all indications in the European Economic Area, Switzerland, the United Kingdom, Australia, and New Zealand.

Results of Operations

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

Year Ended December 31,

Cost and operating expenses:

Gain on sale of non-financial asset — (105.0) 105.0

Total other income (expense), net 7.7 (0.7) 8.4

Provision for income taxes — (0.4) 0.4

Revenue

License and Other

In January 2025, we granted an exclusive license to Norgine to distribute, market and sell our product for all indications in the European Economic Area, Switzerland, the United Kingdom, Australia and New Zealand following regulatory approval. For the year ended December 31, 2025, we recognized $27.6 million for the delivery of the license and $1.0 million for the provision of research and development services to Norgine. We had no license or other revenue during the year ended December 31, 2024.

Product Revenue, Net

We began recognizing product sales in June 2024 following FDA approval of XOLREMDI on April 29, 2024 and its subsequent commercial launch in the United States. Net product sales were as follows for years ended December 31, 2025 and 2024, and for each of the quarterly periods therein.

First quarter $ 942 $ —

Co-pay assistance payments and rebates to U.S. government payors have comprised the majority of our gross-to-net revenue adjustments. Gross-to-net adjustments were approximately 10% and 9% for the years ended December 31, 2025 and 2024, respectively.

Operating Cost and Expenses:

Cost of Revenue

Cost of revenue primarily consists of amortization of an intangible asset related to accrued and paid milestone payments associated with our license agreement (the “Genzyme Agreement”) with Genzyme Corporation (“Genzyme”), a wholly owned subsidiary of Sanofi, and sales and sublicense-based royalty payments due thereunder. Cost of revenue increased $5.0 million in the year ended December 31, 2025, as compared to the prior year, primarily due to additional royalties in the current year associated with sublicense income from our Norgine Agreement.

Research and Development Expenses

Research and development expenses consist primarily of costs incurred in connection with the development of our product candidates, including employee salaries and related expenses, clinical development expenses, internal and third-party costs of manufacturing our drug products for use in our clinical trials. Research and development expenses also include costs related to compliance with regulatory requirements; and prior to the FDA’s approval of XOLREMDI in the U.S. in the second quarter of 2024, payments made under third-party licensing agreements were charged to research and development expense.

Following our strategic restructuring announced during the first quarter of 2025, substantially all of our research and development has been focused on our one product candidate, mavorixafor. The following table shows external costs incurred by product candidate (primarily external contract research organization costs) and unallocated research and development costs, primarily consisting of employee salaries and related expense for our research and development organization.

Year Ended December 31,

Direct research and development expenses by product candidate:

Total research and development expenses $ 72.7 $ 81.6 $ (8.9)

Research and development expenses decreased by$8.9 million in the year ended December 31, 2025 as compared to the prior year primarily due to decreases in spending associated with our 2025 strategic restructurings, including lower spending on non-clinical programs, lower consulting fees, lower drug substance manufacturing costs, and lower regulatory costs. For the year ended December 31, 2025, unallocated expense includes $2.0 million in severance charges for terminated employees. The overall decrease in research and development expenses in the current year was partially offset by higher clinical costs associated with our 4WARD trial.

General and Administrative Expenses

General and administrative expenses consist primarily of salaries and related costs, including stock-based compensation, for personnel in executive, finance, and administrative functions. General and administrative expenses also include direct and allocated facility-related costs as well as professional fees for legal, patent, consulting, investor and public relations, accounting, and audit services.

General and administrative expenses decreased by approximately $18.1 million in the year ended December 31, 2025 as compared to the prior year. General and administrative expenses include $5.0 million in severance charges for terminated employees in the year ended December 31, 2025. The decrease to general and administrative expenses was primarily due to an $8.0 million decrease in compensation expense due to lower head count in our sales, general and administrative functions, and a decrease of $9.0 million in sales and marketing expenses in the current year as compared to the prior year during which we incurred commercialization sales and marketing launch costs related to XOLREMDI. These decreases in general and administrative expenses were partially offset by higher severance costs associated with our 2025 strategic restructurings and higher legal costs in the current year.

Other Income (Expense), Net

Year Ended December 31,

(in millions)

Interest income $ 4.6 $ 5.8 $ (1.2)

Interest expense (8.9) (8.8) (0.1)

Change in fair value of Class C warrant liability 12.8 1.9 10.9

Other (expense) income, net (0.8) 0.4 (1.2)

Total other income (expense), net $ 7.7 $ (0.7) $ 8.4

Other income (expense), net, increased approximately $8.4 million in the year ended December 31, 2025 as compared to the prior year primarily due to higher gains in the current year on fair value adjustments related to our Class C warrants, partially offset by lower interest income earned on our marketable security investment portfolio.

Provision for Income Taxes

Our income tax provision of $41.0 thousand for the year ended December 31, 2025, which was primarily related to our Austrian subsidiary, was lower than our income tax provision in the prior year. Our income tax provision for the year ended December 31, 2024 of $0.3 million reflected U.S. federal and state taxable income that included the sale of a priority review voucher, generating $105.0 million of taxable income, partially offset by available deductions, net operating loss carryforwards, which were limited under IRC 382 due to several qualifying ownership changes, and available research and development credits. We will continue to maintain a full valuation allowance against net deferred tax assets, including net operating loss carryforwards, until we are able to consistently generate sufficient taxable income to realize the benefit of our net deferred tax assets.

Liquidity and Capital Resources

Sources of Liquidity

To date, we have funded our operations primarily with proceeds from sales of common stock, warrants, prefunded warrants and preferred stock, proceeds from the issuance of convertible debt and borrowings under loan and security agreements.

Public and Private Equity Offerings. Over the past several years we have funded our operations primarily from sales of common stock, warrants and prefunded warrants through both public offerings and private placements. Most

recently in August 2025, we sold shares of common stock and, in lieu of common stock to certain investors, pre-funded warrants to purchase shares of common stock in a private placement offering (the “Q3 2025 PIPE”) resulting in net proceeds of $81.0 million, after deducting placement agent fees and offering expenses. In addition, in Q4 2025 we completed an underwritten public offering of 52,844,000 shares of our common stock (inclusive of 6,984,000 shares pursuant to the exercise in full of the underwriters’ option to purchase additional shares) at a public offering price of $2.90 per share and, in lieu of

common stock to certain investors, prefunded warrants to purchase up to 700,000 shares of our common stock at a price of $2.899 per pre-funded warrant, for net proceeds of $145.6 million, after underwriting discounts and offering expenses.

ATM Sales Agreement. We are party to a Controlled Equity OfferingSM Sales Agreement (“ATM”), dated as of August 7, 2020, pursuant to which we may offer and sell shares of our common stock through one or more investment banks. To date, for the year ended December 31, 2025 and for the three months ended December 31, 2025, we have sold $24.2 million, $9.7 million, and $0.7 million, respectively, of our common stock, net of offering costs, under the ATM. Pursuant to our Registration Statement on Form S-3 that became effective on August 24, 2023 and the related ATM prospectus contained therein, we may offer and sell shares of our common stock having an aggregate offering price of up to an additional $65.3 million.

Product Sales and License Revenue. We commercially launched XOLREMDI in the second quarter of 2024 following the approval of XOLREMDI by the FDA on April 29, 2024. To date, we have generated $9.1 million of net product revenue from the sale of XOLREMDI. For the year ended December 31, 2025, we generated $27.6 million in license revenue from the exclusive licensing and supply agreement with Norgine.

Hercules Loan Agreement. We are a party to a loan and security agreement (the “Hercules Loan Agreement”), which provides for a term loan facility of up to $107.5 million, under which we have borrowed an aggregate of $75.0 million of term loans to date, representing the maximum borrowings as of December 31, 2025. The term loan facility requires that we make interest-only payments through maturity on July 1, 2027 and requires that we meet certain operational and financial covenants. See Note 11 to the consolidated financial statements contained herein for a full description of our Hercules Loan Agreement.

Historical Cash Flows

The following table summarizes our cash flow activities for each of the periods presented:

Year Ended December 31,

(in millions)

Changes in operating assets and liabilities (2.6) 2.7

Net cash used in operating activities (85.6) (130.9)

Net cash provided by investing activities 8.2 67.0

Net cash provided by financing activities 238.6 20.3

Cash, cash equivalents and restricted cash, beginning of period 56.5 100.2

Cash, cash equivalents and restricted cash, end of period $ 217.9 $ 56.5

Operating Activities

During the year ended December 31, 2025, net cash used in operating activities was $85.6 million, primarily resulting from net losses of $79.2 million adjusted for net non-cash income of $3.8 million, primarily related to gains on changes to the fair value of our Class C warrants that are measured quarterly at fair value, and $2.6 million of changes to operating assets and liabilities primarily related to a reduction in accounts payable and accrued expenses. Net cash used in operating activities for the year ended December 31, 2024 was $130.9 million, primarily resulting from our operating losses of $142.5 million adjusted for noncash expenses of $8.9 million and changes in our operating assets and liabilities of $2.7 million. Noncash expenses primarily include stock-based compensation expense of $8.2 million and non-cash lease expense of $1.6 million, partially offset by $1.9 million of non-cash gains on the change in fair value of our Class C Warrant liability.

Investing Activities

During the year ended December 31, 2025, cash provided by investing activities of $8.2 million primarily includes net sales of short-term marketable securities. During the year ended December 31, 2024, cash provided by investing activities was $67.0 million, primarily due to the receipt of $105.0 million of cash from the sale of a PRV, partially offset by net investments in short-term marketable securities.

Financing Activities

During the year ended December 31, 2025, cash provided by financing activities of $238.6 million was primarily due to net proceeds of $226.6 million from the sale our common stock and pre-funded warrants in private placement and public offerings and $11.9 million from sales of our common stock through our ATM program and purchase agreement with Lincoln Park Capital Fund LLC. Cash provided by financing activities for the year ended December 31, 2024 included $20.0 million of new borrowings on our loan facility.

Capital Resources

Based on our cash, cash equivalents and marketable securities on hand as of March 17, 2026, and our current operating plan, we believe that our cash, cash equivalents and marketable securities will allow us to fund operations for at least the next 12 months.

Capital Requirements

During the year ended December 31, 2025, we sold shares of common stock and, in lieu of common stock to certain investors, pre-funded warrants to purchase shares of common stock in a private placement offering and an underwritten public offering for aggregate net proceeds of $226.6 million, after placement agent and underwriting fees and offering expenses. These financing events extend our ability to fund our operations and financial obligations into 2028. We expect to continue to incur operating losses as we advance our lead drug candidate through the 4WARD trial. Until we reach profitability, we will need to raise additional capital, which cannot be assured, to fund our operations and meet our financial obligations beyond this period. Such additional capital could be raised through a combination of equity offerings, debt financings, other third-party funding, marketing and distribution arrangements, or other collaborations and strategic alliances. If we are unable to obtain funding, we could be forced to delay, reduce, or eliminate some or all of our research and development programs, product portfolio expansion or commercialization efforts, which would adversely affect our business prospects, or we may be unable to continue operations and may need to restructure our obligations in a court-supervised process or otherwise.

Due to the numerous risks and uncertainties associated with the future sale of our approved drug product and the research, development, and commercialization of future product candidates, we are unable to estimate the exact amount of our funding requirements. Our short-term and long-term funding requirements will depend on and could increase significantly as a result of many factors, including:

•the scope, number, initiation, progress, timing, costs, design, duration, any potential delays, and results of clinical trials and nonclinical studies for our current or future product candidates, particularly our Phase 3 clinical trial of mavorixafor for the treatment of individuals with chronic neutropenic disorders;

•the outcome, timing and cost of regulatory reviews, approvals or other actions to meet regulatory requirements established by the FDA and comparable foreign regulatory authorities, including the potential for the FDA or comparable foreign regulatory authorities to require that we perform more studies for our product candidates than those that we currently expect;

•our ability to obtain marketing approval for our product candidates;

•the cost of filing, prosecuting, defending and enforcing our patent claims and other intellectual property rights covering our product and product candidates, including any such patent claims and intellectual property rights that we have licensed from Genzyme pursuant to the terms of our license agreement with Genzyme;

•our ability to maintain, expand and defend the scope of our intellectual property portfolio, including the cost of defending intellectual property disputes, including patent infringement actions brought by third parties against us or our product or product candidates;

•our ability to establish and maintain licensing, collaboration or similar arrangements on favorable terms and whether and to what extent we retain development or commercialization responsibilities under any new licensing, collaboration or similar arrangement;

•the success of any other business, product or technology that we acquire or in which we invest;

•the costs of acquiring, licensing or investing in businesses, product candidates and technologies;

•the effect of competing technological and market developments; and

•the costs to continue operating as a public company.

Critical Accounting Policies and Significant Judgments and Estimates

Our consolidated financial statements are prepared in accordance with generally accepted accounting principles in the United

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

While our significant accounting policies are described in more detail in Note 2 to our consolidated financial statements included elsewhere in this Annual Report, we believe that the following accounting policies are those most critical to the judgments and estimates used in the preparation of our consolidated financial statements.

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

•vendors in connection with preclinical development activities;

•CROs and investigative sites in connection with preclinical studies and clinical trials; and

•CMOs in connection with the production of preclinical and clinical trial materials.

We base the expense recorded related to external research and development on our estimates of the services received and efforts expended pursuant to quotes and contracts with multiple CMOs and CROs that supply, conduct and manage preclinical studies and clinical trials on our behalf. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows. There may be instances in which payments made to our vendors will exceed the level of services provided and result in a prepayment of the expense. Payments under some of these contracts depend on factors such as the successful enrollment of patients and the completion of clinical trial milestones. In accruing service fees, we estimate the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from the estimate, we adjust the accrual or the amount of prepaid expenses accordingly.

Although we do not expect our estimates to be materially different from amounts actually incurred, our understanding of the

status and timing of services performed relative to the actual status and timing of services performed may vary and may result in reporting amounts that are too high or too low in any particular period. To date, there have not been any material adjustments to our prior estimates of accrued research and development expenses.

Stock-Based Compensation. We measure all stock-based awards granted to employees, directors and consultants based on the

grant-date fair value of the award and recognized compensation expense, net of estimated forfeitures, over the requisite service

period, which is generally the vesting period of the respective award. The stock-based awards that we have issued to date include a service-based vesting condition, and the expense for these awards is recognized using the straight-line method. We have also issued stock-based awards with performance-based vesting conditions that vest in part upon our achievement of operational milestones and over time thereafter for the subsequent two years as the employee continues to provide services. We assess the probability of achievement of these operational milestones and recognize stock-based compensation for these awards using the accelerated attribution model based on the fair value of the awards as of the date of grant and our best estimate of the date each operational milestone will be achieved. We update our estimates related to the probability and timing of achievement of the operational milestones each period until the award either vests or is forfeited.

The fair value of stock option grants is estimated on the date of grant using the Black-Scholes option-pricing model, which uses as inputs the fair value of our common stock and assumptions we make for the volatility of our common stock, the expected term of the stock options, the risk-free interest rate for a period that approximates the expected term of our stock options and an expected dividend yield. Prior to the closing of the merger with Arsanis Inc in March 2019 and the listing of our common stock on the Nasdaq Capital Market, our board of directors historically determined, as of the date of each option grant and with input

from our management, and the assistance of a third-party valuation specialist, the estimated fair value of our common stock on the date of grant based on a number of objectives and subjective factors. Since the merger and the listing of our common stock on the Nasdaq Capital Market, we have relied on the market price of our common stock to determine the fair value on the date of grant. As our common stock does not have a sufficient history of trading, we estimate our volatility based on the historical volatility of publicly traded peer companies. We estimate the expected term of our stock awards by utilizing the “simplified” method, which calculates the expected term based on the weighted average midpoint of the award’s vesting and expiration dates. We determine the risk-free interest rate by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. We estimate that no dividends will be paid as we do not expect to pay cash dividends in the foreseeable future.

The assumptions underlying these valuations represent the best estimates of our management, which involve inherent uncertainties and the application of our judgment. As a result, if factors or expected outcomes change and we use significantly different assumptions or estimates, the resulting share-based compensation expense could be materially different.

Goodwill. Business combinations are accounted for under the acquisition method. The total purchase price of an acquisition is

allocated to the underlying identifiable net assets, based on their respective estimated fair values as of the acquisition date. Determining the fair value of assets acquired and liabilities assumed requires management’s judgment and often involves the use of significant estimates and assumptions, including assumptions with respect to future cash inflows and outflows, probabilities of success, discount rates, and asset lives, among other items. Assets acquired and liabilities assumed are recorded at their estimated fair values. The excess of the purchase price over the estimated fair values of the net assets acquired is recorded as goodwill.

Goodwill is tested quantitatively for impairment at the reporting unit level annually in the fourth quarter, or more frequently when events or changes in circumstances indicate that the asset might be impaired. Examples of such events or circumstances include, but are not limited to, a significant adverse change in legal or business climate, an adverse regulatory action or unanticipated competition.

We have determined that we operate in a single operating segment and have a single reporting unit. To perform its quantitative test, we compare the fair value of our single reporting unit to the carrying value of its net assets, including goodwill. We use our market capitalization (common shares outstanding multiplied by the price per share of our common stock) to measure the fair value of the reporting unit. If the fair value of the reporting unit exceeds the carrying value of its net assets, goodwill is not impaired, and no further testing is required. If the fair value of the reporting unit is less than the carrying value, we measure the impairment loss as the excess of the carrying value over the fair value of the reporting unit. See Note 6 for more information on our goodwill impairment test as of December 31, 2025.

Intangible Assets,Net. Definite-lived intangible assets related to capitalized milestones under license agreements are amortized on a straight-line basis, which aligns with the pattern over which the economic benefit of the intangible assets is consumed, over their remaining useful lives, which are estimated to be the remaining patent life. If our estimate of the product’s useful life is shorter than the remaining patent life, then a shorter period is used. Amortization expense is recorded as a component of cost of revenue on the consolidated statements of operations and comprehensive loss.

Revenue Recognition. We recognize revenue when our customers obtain control of the promised good, such as our drug product or licensed intellectual property rights, in an amount that reflects the consideration that we expect to receive in exchange for those goods. We perform the following five steps to determine the amount of revenue to recognize: (1) identify the customer and contract with the customer; (2) identify the performance obligations in the contract; (3) determine the transaction price, adjusted for variable consideration resulting from potential returns, rebates, discounts, and down-stream charges; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when we satisfy the performance obligations, which is upon shipment of our drug product to the customer or delivery of licensed rights to the customer.

As part of the accounting for contracts with our customers, we make significant judgments, primarily related to the estimation of the amount of variable consideration to include in the transaction price upon delivery of our drug product or licensed rights. The variable consideration includes estimates for discounts, product returns, and rebates that will be due to U.S. federal and state payors, such as Medicaid, based on agreements that we have with these payors who provide medical insurance to the end patient, and estimated co-pay assistance payments for patients who enroll in our patient assistance program. These variable payments are considered a reduction of the transaction price and must be estimated at the time our product is delivered to the customer. For our license arrangements, we will receive milestone payments based on our achievement of defined operational events or cumulative sales levels achieved. When we conclude that the achievement of such milestones is probable, we include the value of the milestone in the transaction price using the most likely amount method. For product sales, we determine the

amount of variable consideration to include in the transaction price by using the expected value method. Net revenue recognized for each period is the amount for which, based on our estimate, it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, we re-evaluate these estimates based on new information and actual operational trends and, if necessary, adjust these variable consideration estimates. Any such adjustments are recorded on a cumulative catch-up basis in the period of the adjustment.

Smaller Reporting Company Status

We are a smaller reporting company (“SRC”) as defined by Rule 12b-2 of the Exchange Act and Item 10(f)(1) of Regulation S-K. We may take advantage of certain of the scaled disclosures available to smaller reporting companies for so long as (i) our voting and non-voting common stock held by non-affiliates is less than $250.0 million measured on the last business day of our second fiscal quarter or (ii) our annual revenue is less than $100.0 million during the most recently completed fiscal year and our voting and non-voting common stock held by non-affiliates is less than $700.0 million measured on the last business day of our second fiscal quarter.

Item 7A. Quantitative and Qualitative Disclosures About Market Risk

As an SRC, we are not required to provide the information requested by this Item.

Item 8. Financial Statements and Supplementary Data

The financial statements required to be filed pursuant to this Item 8 are appended to this Annual Report.

The financial statements contain a Report of Independent Registered Public Accounting Firm PricewaterhouseCoopers LLP, Boston, Massachusetts, US (Firm ID 238).

An index of those financial statements is found in Item 15 of Part IV of this Annual Report.

Item 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosures

None.

Item 9A. Controls and Procedures

Evaluation of Disclosure Controls and Procedures

We maintain disclosure controls and procedures that are designed to ensure that information required to be disclosed in the reports that we file or submit under the Exchange Act is recorded, processed, summarized, and reported within the time periods specified in the SEC’s rules and forms and accumulated and communicated to our management, including our principal executive officer and principal financial officer, to allow timely decisions regarding required disclosure.

Our management, with the participation of our principal executive officer and principal financial officer, evaluated the effectiveness of our disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) as of December 31, 2025, and have concluded that, based on such evaluation, our disclosure controls and procedures were effective as of December 31, 2025 at the reasonable assurance level. Our management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving their objectives, and management necessarily applies its judgment in evaluating the cost-benefit relationship of possible controls and procedures.

Management’s Annual Report on Internal Control over Financial Reporting.

Our management is responsible for establishing and maintaining adequate internal control over financial reporting, as such term is defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act. Our management, including our Chief Executive Officer and Chief Financial Officer, conducted an evaluation of the effectiveness of our internal control over financial reporting based on the criteria set forth in Internal Control-Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission. Based on its evaluation under the criteria set forth in Internal Control-Integrated Framework, our management concluded that our internal control over financial reporting was effective as of December 31, 2025.

Changes in Internal Control Over Financial Reporting

There were no changes in our internal control over financial reporting that occurred during the three months ended December 31, 2025 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

Item 9B. Other Information

Rule 10b5-1 Trading Plans

During the three months ended December 31, 2025, no director or Section 16 officer adopted or modified any Rule 10b5-1 trading arrangements or non-Rule 10b5-1 trading arrangements (in each case, as defined in Item 408(a) of Regulation S-K).

Item 9C. Disclosure Regarding Foreign Jurisdictions That Prevent Inspections

Not applicable.

PART III

Item 10. Directors, Executive Officers and Corporate Governance

The information required by this item is incorporated herein by reference to the information set forth in the sections titled “Proposal 1- Election of Directors,” “Information Regarding the Board of Directors and Corporate Governance,” “Executive Officers,” “Insider Trading Policy” and, if applicable, “Delinquent Section 16(a) Reports” in our Definitive Proxy Statement on Schedule 14A relating to our 2026 Annual Meeting of Stockholders, which we intend to file with the SEC within 120 days of the end of our fiscal year ended December 31, 2025 (the “2026 Proxy Statement”), and is incorporated herein by reference (excluding pay versus performance disclosure).

Information regarding our Code of Business Conduct and Ethics (the “Code of Conduct”) required by this item will be contained in our 2026 Proxy Statement under the caption “Information Regarding the Board of Directors and Corporate Governance – Code of Ethics,” and is hereby incorporated by reference. If we make any substantive amendments to the Code of Conduct or grant any waiver from a provision of the Code of Conduct to any executive officer or director, we will promptly disclose the nature of the amendment or waiver on our website. The full text of our Code of Conduct is available at the compliance and ethics section of our website at https://investors.x4pharma.com/corporate-governance/governance-overview. The reference to our website address does not constitute incorporation by reference of the information contained at or available through our website, and you should not consider it to be a part of this Annual Report on Form 10-K.

We intend to satisfy the disclosure requirement under Item 5.05 of Form 8-K regarding an amendment to, or waiver from, a provision of this Code of Business Conduct and Ethics by posting such information on our website, at the address and location specified above and, to the extent required by the listing standards of The Nasdaq Global Select Market, by filing a Current Report on Form 8-K with the SEC, disclosing such information.

Item 11. Executive Compensation

The information required by this item is incorporated herein by reference to the information set forth in the sections titled “Executive Compensation” in our 2026 Proxy Statement.

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

The information required by this item is incorporated herein by reference to the information set forth in the section titled “Security Ownership of Certain Beneficial Owners and Management” and “Equity Compensation Plan Information” in our 2026 Proxy Statement.

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

The information required by this item is incorporated herein by reference to the information set forth in the section titled “Transactions with Related Persons and Indemnification” and “Information regarding the Board of Directors and Corporate Governance” in our 2026 Proxy Statement.

Item 14. Principal Accountant Fees and Services

The information required by this item is incorporated herein by reference to the information set forth in the section titled “Principal Accountant Fees and Services” contained in our 2026 Proxy Statement.

Item 15. Exhibit and Financial Statement Schedules

(1) Financial Statements

The following documents are included on pages F-1 through F-39 attached hereto and are filed as part of this Annual Report.

Page

Report of Independent Registered Public Accounting Firm F-2

PricewaterhouseCoopers LLP Boston, MA (Firm ID 238)

Consolidated Balance Sheets F-4

Consolidated Statements of Operations and Comprehensive Loss F-5

Consolidated Statements of Stockholders’ Equity F-6

Consolidated Statements of Cash Flows F-7

Notes to Consolidated Financial Statements F-8

(2) Financial Statement Schedules:

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

(3) Exhibits

Incorporated by Reference to:

ExhibitNo. Exhibit Description Form Exhibit No. Filing Date File No.

101.INS* Inline XBRL Instance Document

101.SCH* Inline XBRL Taxonomy Extension Schema Document

101.CAL* Inline XBRL Taxonomy Extension Calculation Linkbase Document

101.DEF* Inline XBRL Taxonomy Extension Definition Linkbase Document

101.LAB* Inline XBRL Taxonomy Extension Label Linkbase Document

101.PRE* Inline XBRL Taxonomy Extension Presentation Linkbase Document

* Filed herewith

** The certification attached as Exhibit 32.1 accompanying this Annual Report on Form 10-K is not deemed filed with the Securities and Exchange Commission and is not to be incorporated by reference into any filing of the Company under the Securities Act of 1933, as amended, or the Securities Exchange Act of 1934, as amended, whether made before or after the date of this Annual Report on Form 10-K, irrespective of any general incorporation language contained in such filing.

@ Indicates management contract or compensatory plan.

Item 16. Form 10-K Summary

None.

SIGNATURES

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

X4 PHARMACEUTICALS, INC.

Date: March 17, 2026 By: /s/ Adam R. Craig

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

Signature Title Date

/s/ Adam R. Craig President, Chief Executive Officer and Director March 17, 2026

Adam R. Craig, M.D., Ph.D., M.B.A. (Principal Executive Officer)

/s/ David Kirske Chief Financial Officer and Treasurer March 17, 2026

David Kirske (Principal Financial Officer and Principal Accounting Officer)

/s/ Michael S. Wyzga Lead Independent Director March 17, 2026

Michael S. Wyzga

/s/ Gary J. Bridger Director March 17, 2026

Gary J. Bridger, Ph.D.

/s/ Francoise De Craecker Director March 17, 2026

Francoise De Craecker

/s/ Murray W. Stewart Director March 17, 2026

Murray W. Stewart, M.D.

INDEX TO CONSOLIDATED FINANCIAL STATEMENTS

Page

Report of Independent Registered Public Accounting Firm F-2

Consolidated Balance Sheets F-4

Consolidated Statements of Operations and Comprehensive Loss F-5

Consolidated Statements of Stockholders’ Equity F-6

Consolidated Statements of Cash Flows F-7

Notes to Consolidated Financial Statements F-8

F-1

Report of Independent Registered Public Accounting Firm

TotheBoard of Directors and Stockholders of X4 Pharmaceuticals, Inc.

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of X4 Pharmaceuticals, Inc. and its subsidiaries (the “Company”) as of December 31, 2025 and 2024, and the related consolidated statements of operations and comprehensive loss, of stockholders’ equity and of cash flows for each of the three years in the period ended December 31, 2025, including the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2025 in conformity with accounting principles generally accepted in the United States of America.

Basis for Opinion

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

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

Our audits included performing procedures to assess the risks of material misstatement of the consolidated financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the consolidated financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the consolidated financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matters

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

External Research and Development Costs

As described in Note 2 to the consolidated financial statements, costs associated with internal research and development and external research and development services, including drug development and preclinical studies, are expensed as incurred. The Company’s research and development expense for the year ended December 31, 2025 was $72.7 million, a portion of which relates to external research and development costs. Management recognizes external research and development costs based on an evaluation of the progress to completion of specific tasks using information provided to the Company by its service providers. As disclosed by management, this process involves reviewing open contracts and purchase orders, communicating with applicable personnel to identify services that have been performed, and estimating the level of service performed and the associated cost incurred for the service when the Company has not yet been invoiced or otherwise notified of actual costs.

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

Addressing the matter involved performing procedures and evaluating audit evidence in connection with forming our overall opinion on the consolidated financial statements. These procedures included, among others, testing external research and development costs on a sample basis, which included tracing relevant information to the underlying contract research

F-2

organization and contract manufacturing organization agreements, purchase orders, invoices received, and information received from certain third party service providers, where applicable.

/s/ PricewaterhouseCoopers LLP

Boston, Massachusetts

We have served as the Company’s auditor since 2016.

F-3

X4 PHARMACEUTICALS, INC.

CONSOLIDATED BALANCE SHEETS

(In thousands, except share and per share amounts)

ASSETS

Current assets:

Research and development incentive receivable — 640

Prepaid expenses and other current assets 3,527 5,588

Property and equipment, net 182 776

LIABILITIES AND STOCKHOLDERS’ EQUITY

Current liabilities:

Deferred revenue 464 —

Current portion of lease liability 994 1,251

Long-term debt, including accretion, net of discount 76,291 75,425

Lease liabilities — 1,410

Deferred revenue 621 —

Commitments and contingencies (Note 13)

Stockholders’ equity:

Accumulated other comprehensive loss (109) (122)

Total liabilities and stockholders’ equity $ 290,461 $ 146,447

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

F-4

X4 PHARMACEUTICALS, INC.

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS

(In thousands, except share and per share amounts)

Year Ended December 31,

License and other revenue $ 28,590 $ — $ —

Costs and operating expenses:

Gain on sale of non-financial asset — (105,000) —

Other income (expense), net:

Provision for income taxes 41 310 78

Net loss per share: basic and diluted $ (1.87) $ (5.59) $ (17.07)

Other comprehensive loss, net of tax:

Change in net unrealized gains on marketable debt securities 13 (3) —

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

F-5

X4 PHARMACEUTICALS, INC.

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY

(In thousands, except share amounts)

Shares Amount

Stock-based compensation expense 8,687 8,687

Issuance of common stock under employee stock purchase plan 21,185 — 297 297

Vesting of restricted stock units 95,893 — 2 2

Unrealized loss on marketable securities (3) (3)

Issuance of common stock under employee stock purchase plan 38,769 — 89 89

Vesting of restricted stock units 239,924 — — —

Unrealized losses on marketable securities 13 13

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

F-6

X4 PHARMACEUTICALS, INC.

CONSOLIDATED STATEMENTS OF CASH FLOWS

(In thousands)

Year Ended December 31,

Cash flows from operating activities:

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

Depreciation and amortization expense 1,277 796 419

Gain on sale of non-financial asset — (105,000) —

Change in fair value of warrant liability (12,778) (1,928) (7,074)

Changes in operating assets and liabilities:

Accrued expenses and other long-term liabilities (2,025) 7,169 1,608

Deferred revenue 1,085 — —

Cash flows from investing activities:

Acquisition of intangible asset (3,000) (7,000) —

Proceeds from sale of non-financial asset — 105,000 —

Acquisition of property and equipment — (326) (60)

Net cash provided by (used in) investing activities 8,154 66,990 (14,883)

Cash flows from financing activities:

Proceeds from borrowings under loan and security agreement — 20,000 22,500

Repayments of borrowings under loan and security agreement — — (2,064)

Acquisition of intangible assets included in accrued expenses $ 500 $ 3,500 $ —

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

F-7

X4 PHARMACEUTICALS, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

1. Description of Business and Basis of Presentation

X4 Pharmaceuticals Inc., together with its subsidiaries, also referred to in these financial statements as “we,” “us,” “our,” the “Company” and “X4,” is a biopharmaceutical company developing and commercializing novel therapeutics for the treatment of rare hematology diseases. The Company continues to progress its global, pivotal Phase 3 clinical trial, (the “4WARD” trial) to evaluate the efficacy, safety, and tolerability of oral, once-daily mavorixafor (with or without stable doses of granulocyte colony-stimulating factor (“G-CSF”)) in people with congenital, acquired primary autoimmune, or idiopathic chronic neutropenia (“CN”) who are experiencing recurrent and/or serious infections. The 52-week trial is a randomized, double-blind, placebo-controlled, multicenter study aiming to enroll up to 176 patients, with full enrollment expected in the third quarter of 2026. The U.S. Food and Drug Administration (“FDA”) has granted Fast Track designation to mavorixafor for the treatment of CN, which is defined as periods lasting more than three months persistently or intermittently where there are abnormally low levels of neutrophils circulating in the blood, and may be idiopathic (of unknown origin), cyclic (episodes typically occurring every three weeks), or congenital (of genetic causation). CN disorders are rare blood conditions similarly characterized by increased risks of infections and cancer due to abnormally low levels of neutrophils in the body. In all cases, the CXCL12/CXCR4 pathway is the key regulator of neutrophil release from the bone marrow. The Company has one commercially approved product, XOLREMDI ® (mavorixafor), which has received accelerated approval in the United States from the FDA for use as an oral, once-daily therapy in patients 12 years of age and older with WHIM (warts, hypogammaglobulinemia, infections, and myelokathexis) syndrome, to increase the number of circulating mature neutrophils and lymphocytes. WHIM syndrome is a rare combined primary immunodeficiency and chronic neutropenic disorder. The Company is committed to making XOLREMDI available to patients in need in the U.S. while maintaining its focus on its long-term strategy to successfully complete the 4WARD trial in patients with moderate and severe CN. The Company is headquartered in Boston, Massachusetts.

Basis of Presentation

On April 28, 2025, the Company effected a 1-for-30 reverse stock split of its common stock (the “Reverse Stock Split”). Unless otherwise noted, all references to common stock share and per share amounts in this Annual Report on Form 10-K have been retroactively adjusted to reflect the Reverse Stock Split.

Principles of Consolidation

The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, including X4 Pharmaceuticals (Austria) GmbH, which is incorporated in Vienna, Austria, and X4 Therapeutics, Inc. All intercompany accounts and transactions have been eliminated.

Liquidity

The Company has evaluated whether there are certain conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the consolidated financial statements are issued. Although the Company has an approved drug product, licensing and sales of its drug product over the next 12 months will not be sufficient to fund its operating expenses. Since inception, the Company has incurred significant operating losses and negative cash flows from operations, and the Company expects to continue to generate operating losses and negative cash flows from operations for the foreseeable future. For the year ended December 31, 2025, the Company’s net loss was $79.2 million and net cash used in operating activities was $85.6 million. As of December 31, 2025, the Company had $253.0 million of cash, cash equivalents and short-term marketable securities, and an accumulated deficit of $594.6 million.

Based on its current operating plan, the Company believes (a) that its current cash, cash equivalents and short-term marketable will be sufficient to fund its operations for at least the next 12 months and (b) it will continue to comply with all covenants under the Hercules Loan Agreement, as defined and further described in Note 11, through at least the 12-month period from the issuance date of these consolidated financial statements.

The Company is subject to risks common to companies in the biopharmaceutical industry including, but not limited to, uncertainties relating to conducting preclinical and clinical research and development, the manufacture and supply of products and product candidates for clinical and commercial use, obtaining and maintaining regulatory approvals and pricing and reimbursement for its products and product candidates, market acceptance, managing global growth and operating expenses, availability of additional capital, competition, obtaining and enforcing patents, stock price volatility, dependence on

F-8

X4 PHARMACEUTICALS, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

collaborative relationships and third-party service providers, dependence on key personnel, and from time to time government investigations, litigation, and potential product liability claims.

2. Summary of Significant Accounting Policies

Use of Estimates— The preparation of the Company’s consolidated financial statements in conformity with U.S. Generally Accepted Accounting Principles (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of expenses during the reporting period. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, the accrual of research and development expenses and the impairment or lack of impairment of long-lived assets including operating lease right-of-use assets and goodwill. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates when there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. As of the date of issuance of these consolidated financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, assumptions and judgments or revise the carrying value of its assets or liabilities. Actual results could differ from those estimates, and any such differences may be material to the Company’s consolidated financial statements.

Foreign Currency and Currency Translation— The functional and reporting currency of the Company and its foreign subsidiary, X4 Austria, is the U.S. dollar. Monetary assets and liabilities denominated in a currency other than the U.S. dollar are re-measured into U.S. dollars at the exchange rate prevailing as of the balance sheet date. Non-monetary assets and liabilities acquired in a currency other than U.S. dollars are measured at historical exchange rates prevailing at each transaction date. Exchange gains and losses on translation are included in the consolidated statements of operations and comprehensive loss in other income (expense), net.

Concentrations of Credit Risk and Significant Suppliers— Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents and marketable securities. The Company generally maintains cash balances in various operating accounts at financial institutions that management believes to be of high credit quality in amounts that may exceed federally insured limits. The Company’s marketable securities and cash equivalents are invested in high quality, U.S. government obligations such as U.S. Treasury bills and U.S. government agency obligations. The Company has not experienced losses related to its cash and cash equivalents.

The Company is dependent on third-party manufacturers to supply its drug substance and clinical and commercial drug supply for research and development activities in its programs and for commercial sale. The Company relies and expects to continue to rely on a small number of manufacturers to supply it the active pharmaceutical ingredient and formulated drugs related to its commercial drug supply and for its development these programs. The Company’s sales and these programs could be adversely affected by a significant interruption in these manufacturing services or in the supply of active pharmaceutical ingredients and formulated drugs.

Cash and Cash Equivalents— The Company considers all highly liquid investments with maturities of 90 days or less at the date of purchase to be cash equivalents. Cash equivalents consisted of money market funds, treasury bills and federal government agency notes as of December 31, 2025 and December 31, 2024.

Marketable Securities— Marketable securities consist of short-term debt securities classified as available-for-sale having maturities greater than 90 days, but less than 365 days from the date of acquisition (settlement). The Company determines the appropriate classification of the securities at the time they are acquired and evaluate the appropriateness of such classifications at each balance sheet date. The Company’s marketable securities, which consist of U.S. Treasury securities and federal government agency notes, are classified as available-for-sale securities whose fair value is categorized as Level 2 as their value is based on valuations using significant inputs derived from, or corroborated by, observable market data. The cost of available-for-sale securities sold is based on the specific-identification method. Unrealized gain and losses on available-for-sale are included as a component of other comprehensive loss on the consolidated balance sheet and as a component of total comprehensive loss on the consolidated statement of operations and comprehensive loss until realized. Realized gains and losses on the sale of marketable securities are determined using the specific-identification method and recorded in other

F-9

X4 PHARMACEUTICALS, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(expense) income, net on the accompanying consolidated statements of operations and comprehensive loss. The Company reviews marketable securities for impairment whenever the fair value of a marketable security is less than the amortized cost and evidence indicates that a marketable security’s carrying amount is not recoverable. Unrealized losses are evaluated for impairment under ASC 326, Financial Instruments - Credit Losses, to determine if the impairment is credit-related or noncredit-related. Credit-related impairment is recognized as an allowance on the consolidated balance sheets with a corresponding adjustment to earnings, and noncredit-related impairment is recognized in other comprehensive loss, net of taxes. Evidence considered in this assessment includes reasons for the impairment, compliance with the Company’s investment policy, the severity of the impairment, collectability of the security, and any adverse conditions specifically related to the security, an industry, or geographic area.

Restricted Cash

(in thousands) As of December 31, 2025 As of December 31, 2024

Letter of credit security: Vienna Austria lease $ 224 $ 199

Letter of credit security: Boston lease 579 577

Total restricted cash $ 803 $ 776

In connection with the Company’s lease agreements for its facilities in Boston, Massachusetts and Vienna, Austria, the Company maintains letters of credit, which are secured by restricted cash, for the benefit of the respective landlord. As of December 31, 2025, restricted cash related to the Vienna, Austria lease is included in other current assets and was subsequently converted to cash prior to the issuance of these consolidated financial statements. Restricted cash related to the Boston lease is also included in other current assets.

In accordance with the Company’s Hercules Loan Agreement and as further described in Note 11, the Company at all times must maintain a minimum level of cash of $15.0 million in an account or accounts in which Hercules Capital Inc. (“Hercules”) has a first priority security interest.

The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within consolidated balance sheets to the sum to the total of amounts shown in the Company’s consolidated statements of cash flows as of December 31, 2025 and December 31, 2024:

Restricted cash (non-current) — 776

Total cash, cash equivalents and restricted cash $ 217,852 $ 56,475

Accounts Receivable— Accounts receivable consists of amounts due from customers, net of expected credit losses. The Company’s measurement of expected credit losses is based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. To date, the Company has not experienced any credit losses from its customers. The Company’s contracts with its customers have customary payment terms that generally require payment within 90 days. The Company analyzes amounts that are past due for collectability, and periodically evaluates the creditworthiness of its customers. At December 31, 2025 and December 31, 2024, the Company determined an allowance for credit losses was not required based on the deemed credit worthiness of its customers.

Inventory— Prior to receiving approval from the FDA in April 2024 to sell XOLREMDI (mavorixafor) in the United States, the Company expensed all costs incurred related to the manufacture of mavorixafor as research and development expense due to the inherent risks associated with the development of a drug candidate, the uncertainty about the regulatory approval process and the lack of history for the Company in obtaining of regulatory approval of drug candidates. The Company has capitalized inventory-related costs that have been incurred subsequent to FDA approval, such as the bottling, labelling, and packaging of drug product, and the acquisition of raw materials for the production of drug substance to be used in commercial drug product.

F-10

X4 PHARMACEUTICALS, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

In connection therewith, the Company values inventories at the lower of cost or estimated net realizable value. The Company determines the cost of inventories on a first-in, first-out (“FIFO”) basis. Raw materials and work in process include all inventory costs prior to packaging, and labelling, including raw materials and the active pharmaceutical ingredient used in the drug product. Finished goods include packaged and labelled drug products designated for commercial distribution. Clinical drug supplies are expensed to research and development. Raw materials and work in process that may be used for either research and development or commercial sale are classified as inventory until the material is consumed or otherwise allocated for research and development. If the material may only be used for research and development, it is expensed as research and development.

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

Estimated Useful Life

Office furniture 3 to 7 years

Computer equipment 3 years

Laboratory equipment 3 to 10 years

Leasehold improvements Shorter of lease term or 10 years

Estimated useful lives are periodically assessed to determine if changes are appropriate. Maintenance and repairs are charged to expense as incurred. When assets are retired or otherwise disposed of, the cost of these assets and related accumulated depreciation or amortization are eliminated from the consolidated balance sheet and any resulting gains or losses are included in the consolidated statements of operations and comprehensive loss in the period of disposal. Costs for capital assets not yet placed into service are capitalized as construction-in-progress and depreciated once placed into service.

Right-of-Use Assets and Leases— The Company accounts for leases in accordance with Accounting Standards Codification (“ASC”), Topic 842,Leases(“ASC 842”). Under ASC 842, at the inception of an arrangement, the Company determines whether the arrangement contains a lease based on the unique facts and circumstances present. Leases with a non-cancellable term greater than one year are recognized on the balance sheet as right-of-use assets with associated current and non-current lease liabilities. The Company has elected not to recognize on the balance sheet leases with terms of one year or less. Options to renew a lease are not included in the Company’s initial lease term assessment unless there is reasonable certainty that the Company will renew the lease. If a lease is cancellable without penalty, the Company excludes from the lease term periods following the cancellation notice period unless it is reasonably certain that the Company will not cancel the lease. As the Company’s leases do not provide an implicit rate, the Company estimates the incremental borrowing rate in calculating the present value of the lease payments. The Company utilizes its incremental borrowing rates, which are the rates incurred to borrow on a collateralized basis over a similar term and amount equal to the lease payments in a similar economic environment.

Operating lease liabilities and their corresponding right-of-use assets are recorded based on the present value of lease payments over the expected remaining lease term. Certain adjustments to the right-of-use operating asset may be required for items such as incentives received or accrued rent. The interest rate implicit in lease contracts is typically not readily determinable. As a result, the Company utilizes its incremental borrowing rates, which are the rates it incurs to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. The Company referenced the effective rate of its Hercules Loan Agreement, as adjusted for differences terms, to determine its incremental borrowing rate for each of its operating leases at lease inception.

In accordance with the guidance in ASC 842, components of a lease are split into lease components and non-lease components. Pursuant to a policy election, the Company has elected to account for the lease and non-lease components as a combined lease component.

Impairment of Long-Lived Assets— Long-lived assets consist of property and equipment, operating lease right-of-use assets and definite-lived intangible assets. Long-lived assets to be held and used are tested for recoverability whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset group for recoverability, the Company

F-11

X4 PHARMACEUTICALS, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

compares forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset group to its carrying value. An impairment loss would be recognized in loss from operations when estimated undiscounted future cash flows expected to result from the use of an asset group are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset group over its fair value. To date, the Company has not recorded any material impairment losses on long-lived assets.

Goodwill— Business combinations are accounted for under the acquisition method. The total purchase price of an acquisition is allocated to the underlying identifiable net assets, based on their respective estimated fair values as of the acquisition date. Determining the fair value of assets acquired and liabilities assumed requires management’s judgment and often involves the use of significant estimates and assumptions, including assumptions with respect to future cash inflows and outflows, probabilities of success, discount rates, and asset lives, among other items. Assets acquired and liabilities assumed are recorded at their estimated fair values. The excess of the purchase price over the estimated fair values of the net assets acquired is recorded as goodwill.

The Company has determined that it operates in a single operating segment and has a single reporting unit. To perform its quantitative test, the Company compares the fair value of the reporting unit to its carrying value. If the fair value of the reporting unit exceeds the carrying value of its net assets, goodwill is not impaired, and no further testing is required. If the fair value of the reporting unit is less than the carrying value, the Company measures the amount of impairment loss, if any, as the excess of the carrying value over the fair value of the reporting unit. See Note 6 for more information on the Company’s goodwill impairment tests as of December 31, 2025, 2024 and 2023.

Intangible Assets, Net— Definite-lived intangible assets related to capitalized milestones under license agreements are amortized on a straight-line basis, which aligns with the pattern over which the economic benefit of the intangible assets are consumed, over their remaining useful lives, which are estimated to be the remaining patent life. If the Company’s estimate of the product’s useful life is shorter than the remaining patent life, then a shorter period is used. Amortization expense is recorded as a component of cost of revenue on the consolidated statements of operations and comprehensive loss.

Fair Value Measurements— Certain assets and liabilities of the Company are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable:

•Level 1—Quoted prices in active markets for identical assets or liabilities.

•Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data.

•Level 3—Unobservable inputs that are supported by little or no market activity that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques.

The embedded derivative liability related to the redemption features of the Company’s debt with Hercules as described further below and the Company’s outstanding Class C warrants are carried at fair value and using a Level 3 measurements. The Company’s cash equivalents, which consist of money market funds, which are invested in U.S. Treasury securities and U.S. government agency obligations, are carried at fair value, determined based on Level 1 and Level 2 inputs in the fair value hierarchy described above. The Company’s marketable securities are carried at fair value determined based on Level 2 inputs. The carrying values of the Company’s accounts payable and accrued expenses approximate their fair values due to the short-term nature of these liabilities. The carrying value of the Company’s outstanding loan and security agreement with Hercules

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NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

approximates its fair value at December 31, 2025 because the debt bears interest at a variable market rate and the Company’s credit risk has not materially changed since the inception of the agreement.

Segment Information— The Company has defined its Chief Operating Decision Maker (“CODM”) as its Executive Chairman. The CODM manages the Company’s operations as a single operating segment, which comprises its single reportable segment, for the purposes of assessing performance and making operating decisions. The Company’s focus is on the research, development and commercialization of novel therapeutics for the treatment of rare diseases. See Note 20 for the Company’s segment disclosures required by ASC 280, Segment Reporting.

Revenue Recognition-—The Company records revenue using the guidance of ASC Topic 606,Revenue from Contracts with Customers(“ASC 606”), as amended. Upon the approval by the FDA of the sales and marketing of the Company’s lead product candidate, revenue related to its sale and distribution is accounted for under ASC 606. The Company recognizes revenue when its customer obtains control of promised goods, services or licensed rights, in an amount that reflects the consideration that the Company determines it expects to receive in exchange for those goods, services or licensed rights. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following five steps: (1) identify the customer and contract with the customer; (2) identify the performance obligations in the contract; (3) determine the transaction price, adjusted for variable consideration resulting from potential returns, rebates, discounts, down-stream charges and the probability of achievement of future milestones; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when the Company satisfies its performance obligations, which is upon delivery of the finished product to the customer, delivery of services or delivery of licensed rights.

The Company currently sells its product to a specialty pharmacy, which dispenses the Company’s drug product to patients in the U.S. The Company records revenue when the specialty pharmacy obtains control over the promised good, which occurs at a point in time, typically upon delivery to the specialty pharmacy. The Company has concluded that it provides one performance obligation in its contract with the specialty pharmacy customer and for other customers in this class: the delivery of drug product that has been approved for sale and distribution by the applicable regulatory authority.

The Company has also entered into a license and supply agreement (the “Norgine Agreement”) with Norgine Pharma UK Ltd. (“Norgine”). The terms of the Norgine Agreement contain multiple performance obligations, which include (a) the delivery of a license, (b) WHIM research and development services and (c) CN research and development services. Payments to the Company under this arrangement include non-refundable, upfront license fees; regulatory and sales-based milestone payments and royalties on future product sales.

As part of the accounting for its contract arrangements, the Company makes significant judgments, primarily related to the estimation of the amount of variable consideration to include in the transaction price upon delivery of the Company’s drug product or licensed rights.

•The variable consideration for product sales typically includes estimates for discounts, product returns, rebates due to U.S. federal and state payors, such as Medicaid, based on agreements that the Company has with these payors who provide medical insurance to the end patient, and estimated co-pay assistance payments for patients who enroll in the Company’s patient assistance program. These variable payments are considered a reduction of the Company’s transaction price with its customer and are estimated using the expected value method at the time the Company’s product is delivered to the customer.

•The consideration in license agreements typically includes future regulatory milestone payments, sales-based milestone payments, and royalties on future product sales. The Company has elected to exclude sales-based milestone payments and sales-based royalties from the transaction price under the applicable practical expedient. As such, the remaining variable consideration is generally comprised of future regulatory or operational milestone payments, which are considered for inclusion in the transaction price at the outset of the arrangement and at each reporting period using the most-likely-amount method.

For arrangements which contain multiple performance obligations, the Company allocates the transaction price to each performance obligation based on the estimated relative standalone selling price. The Company estimates the standalone selling price with the objective of determining the price at which the Company would sell such an item if it were to be sold regularly on a standalone basis.

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Net revenue recognized for each period is the amount for which, based on management’s estimate, it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates these estimates based on new information and actual operational trends and if necessary, adjusts these variable consideration estimates. Any such adjustments are recorded on a cumulative catch-up basis in the period of the adjustment.

Cost of Revenue— Cost of revenue consists of drug product costs, including capitalized internal direct and overhead costs associated with the manufacturing, lot release and distribution of XOLREMDI, amortization of intangible assets associated with license agreements and royalty expense. Cost of revenue may also include costs related to excess or obsolete inventory adjustment charges and abnormal manufacturing costs.

Costs to Obtain a Contract with a Customer— The Company capitalizes incremental costs to obtain a contract with a customer, such as external finder’s fees and commissions. Such costs are amortized to sales and marketing expense within general and administrative costs over the estimated life of the customer relationship in proportion to the value of license, products and services provided.

Research and Development Programs— Proceeds under the research and development incentive program from the Austrian government are recognized as other income in an amount equal to the qualifying expenses incurred in each period multiplied by the applicable reimbursement percentage. Incentive income recognized upon incurring qualifying expenses in advance of receipt of proceeds from research and development incentives is recorded in the consolidated balance sheet as research and development incentive receivable.

Research and Development Costs— Costs associated with internal research and development and external research and development services, including drug development and preclinical studies, are expensed as incurred. Research and development expenses include costs for salaries, employee benefits, subcontractors, facility-related expenses, depreciation and amortization, stock-based compensation, third-party license fees, laboratory supplies, and external costs of outside vendors engaged to conduct discovery, preclinical and clinical development activities and clinical trials as well as to manufacture clinical trial materials, and other costs. The Company recognizes external research and development costs based on an evaluation of the progress to completion of specific tasks using information provided to the Company by its service providers. This process involves reviewing open contracts and purchase orders, communicating with the Company’s applicable personnel to identify services that have been performed on its behalf and estimating the level of service performed and the associated cost incurred for the service when the Company has not yet been invoiced or otherwise notified of actual costs.

Nonrefundable advance payments for services to be received in the future for use in research and development activities are recorded as prepaid expenses. Such prepaid expenses are recognized as an expense when the related services have been performed, or when it is no longer expected that the goods will be delivered, or the services rendered.

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

Debt Issuance Costs— Debt issuance costs consist of payments made to secure commitments under certain debt financing arrangements. These amounts are recognized as interest expense over the period of the financing arrangement using the effective interest method. If the financing arrangement is canceled or forfeited, or if the utility of the arrangement to the Company is otherwise compromised, these costs are recognized as interest expense immediately. The Company’s consolidated financial statements present debt issuance costs related to a recognized debt liability as a direct reduction from the carrying amount of that debt liability.

Stock-Based Compensation— The Company measures all stock-based awards granted to employees, nonemployees and directors based on the fair value on the date of the grant and recognizes compensation expense for those awards, net of estimated forfeitures, over the requisite service period, which is generally the vesting period of the respective award. The Company issues stock-based awards with service-based vesting conditions and records the expense for these awards using the straight-line method. The Company has also issued stock-based awards with performance-based vesting conditions that vest in part upon the Company’s achievement of operational milestones and over time thereafter for the subsequent two years as the employee continues to provide services. The Company assesses the probability of achievement of these operational milestones

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and recognizes stock-based compensation for these awards using the accelerated attribution model based on the fair value of the awards as of the date of grant and its best estimate of the date each operational milestone will be achieved.

The Company classifies stock-based compensation expense in its consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified or in which the award recipient’s service payments are classified.

The Company recognizes compensation expense for only the portion of awards that are expected to vest. In developing a forfeiture rate estimate, the Company has considered its historical experience to estimate pre-vesting forfeitures for service-based awards. The impact of a forfeiture rate adjustment is recognized in full in the period of adjustment, and if the actual forfeiture rate is materially different from the Company’s estimate, the Company may be required to record adjustments to stock-based compensation expense in future periods.

The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model, which model includes (a) stock price volatility, based on the historical volatility of the Company’s stock price for the duration of the expected life of the option, (b) the expected term, which is based “simplified” method for awards that qualify as “plain-vanilla” options, (c) the risk-free interest rate, which is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award and (d) expected dividend yield, which considers the fact that the Company has never paid cash dividends on common stock and does not expect to pay any cash dividends in the foreseeable future.

Derivative Liabilities: Hercules Loan Redemption Feature— The Company’s Hercules Loan Agreement contains a redemption feature that, upon an event of default, provides Hercules the option to accelerate and demand repayment of the debt, including a prepayment premium, or, at its election, charge additional contingent interest fees on any overdue interest or principal payments. The redemption feature meets the definition of a derivative instrument as the repayment of the debt contains a substantial premium, resulting in the redemption feature not being clearly and closely related to its host instrument. Accordingly, the Company classifies this derivative as a liability within other liabilities (non-current) on its consolidated balance sheets. The derivative liability was initially recorded at fair value on the date of the Hercules Loan Agreement and is subsequently remeasured to fair value at each reporting date. Changes in the fair value of this derivative liability, which is included in other liabilities, are recognized as a component of other (expense) income, net, in the consolidated statements of operations and comprehensive loss. Changes in the fair value of this derivative liability will continue to be recognized until all amounts outstanding under the Hercules Loan Agreement are repaid or until the Hercules Loan Agreement is terminated.

Comprehensive Loss— For the years ended December 31, 2025, 2024, and 2023, all foreign currency remeasurement gains and losses were included in net loss as the Company has deemed the functional currency of its foreign subsidiary to be the U.S. Dollar. As of December 31, 2025, unrealized gains on the Company’s marketable debt security portfolio are included in accumulated other comprehensive loss on the consolidated balance sheet. Once these gains (losses) are realized, they are included in other (expense) income, net, on the consolidated statements of operations and comprehensive loss.

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

The Company accounts for uncertainty in income taxes recognized in the consolidated financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more-likely-than-not to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the consolidated financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than

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50% likelihood of being realized upon ultimate settlement. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties.

Net Loss per Share—Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of shares of common stock outstanding for the period. Basic shares outstanding includes the weighted average effect of the Company’s outstanding prefunded warrants, the exercise of which requires little or no consideration for the delivery of shares of common stock. Diluted net loss attributable to common stockholders is computed by adjusting net loss attributable to common stockholders to reallocate undistributed earnings based on the potential impact of dilutive securities. Diluted net loss per share attributable to common stockholders is computed by dividing the diluted net loss attributable to common stockholders by the weighted average number of shares of common stock outstanding for the period, including potential dilutive shares of common stock. For purpose of this calculation, outstanding stock options, unvested restricted stock units and warrants to purchase shares of common stock are considered potential dilutive shares of common stock.

Recently Adopted Accounting Standards

In December 2023, the Financial Accounting Standards Board (“FASB”) issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”). ASU 2023-09 requires an entity's annual financial statements to include consistent categories and greater disaggregation of information in the rate reconciliation, and income taxes paid disaggregated by jurisdiction. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. Adoption is either with a prospective method or a fully retrospective method of transition. The Company has adopted ASU 2023-09 for the year ended December 31, 2025, and applied the new disclosure requirements prospectively to the current annual period. Prior period disclosures have not been adjusted to reflect the new disclosure requirements. Please see additional disclosures related to income taxes in Note 17, Income Taxes.

Recently Issued Accounting Standards Not Yet Adopted

In November 2024, the FASB issued ASU 2024-03, Disaggregation of Income Statement Expenses (Topic 220) (“ASU 2024-03”) requiring that public business entities disclose additional information about specific expense categories in the notes to financial statements at interim and annual reporting periods. The amendments in ASU 2024-03 are effective for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. The requirements in ASU 2024-03 may be applied either prospectively to financial statements issued for reporting periods after the effective date or retrospectively to any or all prior periods presented in the financial statements. The Company continues to evaluate the impact of ASU 2024-03.

3. Strategic Restructurings

In the first quarter of 2025, the Company implemented a strategic restructuring of its business operations, workforce and capital spending to focus efforts on advancing mavorixafor to treat patients with CN. As part of this restructuring, the Company (i) implemented a net reduction of its employee headcount by 43 employees, or approximately 30% of its total workforce as of February 2025, including its U.S. commercial field team, (ii) commenced the closure of its research and development facility in Vienna, Austria, (iii) paused its pre-clinical drug candidate programs and (iv) streamlined other spending to support the ongoing clinical development of mavorixafor for the larger population of patients with CN. In addition, in the third quarter of 2025, the Company implemented additional strategic restructuring designed to sharpen its operational focus and align resources with the Company’s long‐term strategy to successfully complete the 4WARD trial in patients with moderate and severe CN. As part of this initiative, the Company further reduced its workforce by an additional approximately 50%. This workforce reduction was substantially completed in the third quarter of 2025.

The Company incurred charges of $7.0 million for severance and other employee termination-related costs related to these strategic restructuring actions, of which $2.0 million is included in research and development and $5.0 million is included in general and administrative expense on the accompanying consolidated statement of operations for the year ended December 31, 2025. During the year ended December 31, 2024, as a result of operational reorganizations, the Company incurred severance and other benefit charges due to employee terminations in the amount of $0.9 million.

Approximately $1.5 million of accrued severance and other employee termination-related costs are included in accrued expenses on the consolidated balance sheet as of December 31, 2025.

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NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

The following table summarizes the Company’s liability recognized in connection with these headcount reductions:

(in thousands)

Severance and other employee-related expenses 861

Cash payments (485)

Severance and other employee-related expenses 7,007

Cash payments (5,951)

4. License Agreements and Funding Arrangements

Research and Development Incentive Program

The Company participated in a research and development incentive program provided by the Austrian government whereby the Company was entitled to reimbursement by the Austrian government for a percentage of qualifying research and development expenses and capital expenditures incurred by the Company’s subsidiary in Austria. As of December 31, 2025, no amounts were due under the program. As of December 31, 2024, $0.6 million was due under the program, which is included in research and development incentive receivable on the consolidated balance sheet. During the year ended December 31, 2025, no amounts were recorded for this program as the Company is in the process of closing the Vienna site. During the years ended December 31, 2024 and 2023, the Company recorded $0.7 million and $0.6 million, respectively, of income related to the program within the consolidated statement of operations as other income.

Genzyme Agreement

In July 2014, the Company entered into a license agreement (the “Genzyme Agreement”) with Genzyme Corporation (“Genzyme”), a wholly owned subsidiary of Sanofi, pursuant to which the Company was granted an exclusive license to certain patents and intellectual property owned or controlled by Genzyme related to the CXCR4 receptor to develop and commercialize products containing licensed compounds (including but not limited to mavorixafor) for all therapeutic, prophylactic and diagnostic uses, with the exception of autologous and allogenic human stem cell therapy. Under the terms of the Genzyme Agreement, the Company is obligated to use commercially reasonable efforts to develop and commercialize licensed products for use in the field in the United States and at least one other major market country. The Company has the right to grant sublicenses of the licensed rights that cover mavorixafor to third parties.

Under the Genzyme Agreement, the Company is obligated to make milestone payments contingent upon the achievement of certain regulatory and sales milestones with respect to licensed products. During the year ended December 31, 2025, a $3.0 million regulatory milestone, which had been previously accrued, was paid after receipt of the European Medicines Agency’s (“EMA”) validation of the Company’s Marketing Authorisation Application (“MAA”) for processing. The payment was recorded as a definite-lived intangible asset as discussed in Note 9.

As of December 31, 2025, the Company is obligated to make future milestone payments in the aggregate amount of up to $10.0 million, including$5.0 million upon the notification by the EMA of regulatory approval of the Company’s MAA for mavorixafor for the WHIM indication, and one-time sales milestone payments of $0.5 million, $1.5 million and $3.0 million on cumulative net sales of $50.0 million, $150.0 million and $300.0 million, respectively. As of December 31, 2025, the Company accrued $0.5 million of sales-based milestones as a component of the definite-lived intangible asset, as management has concluded that the achievement of this milestones is probable.

In addition, for the year ended December 31, 2025, the Company incurred $4.5 million of fees under the Genzyme Agreement as a result of sublicense payments received and sales of licensed product. Such fees were recorded as cost of revenue.

The Company is obligated to pay Genzyme tiered royalties based on net sales of licensed products that the Company commercializes under the agreement. Upon the first sale of the Company’s drug candidate in the U.S., the Company incurs royalties on annual net sales at a rate of 6% up to $150.0 million, 10% on the portion of annual net sales between $150.0

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NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

million and $300.0 million, and 12% thereafter on annual sale over $300.0 million. The Company also incurs a 15% royalty on certain sublicense payments received from sub-licensees.

The obligation to pay royalties for each licensed product expires on a country-by-country basis on the latest of (i) the expiration of licensed patent rights that cover that licensed product in that country, (ii) the expiration of regulatory exclusivity in that country and (iii) ten years after the first commercial sale of such licensed product in that country. Royalty rates are subject to reduction under the agreement in specified circumstances, including in any country if the Company is required to obtain a license from any third party to the extent the Company’s patent rights might infringe the third party’s patent rights, if a licensed product is not covered by a valid claim in that country or if sales of generic products reach certain thresholds in that country. If the Company enters into a sublicense under the Genzyme Agreement, the Company will be obligated to pay Genzyme a percentage of certain upfront fees, maintenance fees, milestone payments and royalty payments paid to the Company by the sublicensee. Under the Genzyme Agreement, the Company will itself manufacture and supply, or enter into manufacturing or supply agreements with Genzyme or third parties to manufacture and supply, clinical and commercial supplies of licensed compounds and each licensed product. The Company is also responsible for all costs related to the filing, prosecution and maintenance of the licensed patent rights.

The Genzyme Agreement will remain in effect until the expiration of the royalty term in all countries for all licensed products. The Genzyme Agreement may be terminated by either party with at least 90 days’ notice in the event of material breach by the other party that remains uncured for 90 days, by either party for insolvency or bankruptcy of the other party, immediately by Genzyme if the Company challenges the licensed patents, or immediately by the Company if a material safety issue arises.

Norgine Agreement

On January 13, 2025, the Company entered into the Norgine Agreement, pursuant to which Norgine was granted an exclusive license to seek regulatory approval and distribute, market and sell the Company’s product mavorixafor within the Field (as defined in the Norgine Agreement), in the European Economic Area, Switzerland, the United Kingdom, Australia and New Zealand (collectively, the “Territory”), following regulatory approval in the Territory. Additionally, Norgine was granted a co-exclusive license to manufacture mavorixafor for the Territory. The Company retains all rights to mavorixafor outside the Territory and specific reserved rights within the Territory. Norgine may grant sublicenses to its affiliates and certain third parties subject to the terms of the Norgine Agreement, except that it may not sublicense the commercial rights granted under the Norgine Agreement for certain countries without X4’s explicit consent.

Pursuant to the terms of the Norgine Agreement, the Company received a one-time, non-refundable, upfront payment of€28.5 million and a regulatory milestone payment of €0.5 million. The Company could receive up to approximately €20.6 million, €20.0 million and €185.0 million upon the achievement of certain regulatory, commercial, and sales milestones, respectively, or €225.6 million in aggregate. The Norgine Agreement also includes escalating double-digit royalties of up to mid-twenties on any future net sales in the Territory. The tiered royalty payments are subject to royalty stacking, and to a material reduction on a country-by-country basis if a generic version of mavorixafor becomes available in the applicable country. The Company and Norgine will collaborate closely on regulatory filings, with the Company continuing to be responsible for the ongoing 4WARD clinical trial evaluating mavorixafor in CN and certain components of pediatric studies for WHIM. Norgine will be responsible for all market access and commercialization activities. The Company also agreed to manufacture and supply mavorixafor to Norgine. Norgine is required to pay a supply price to the Company for the licensed product derived from the Company’s manufacturing costs plus margin in the low teens.

Subject to customary rights of each party to earlier terminate the Norgine Agreement, the term of the Norgine Agreement continues, on a country-by-country basis, until the later of: (i) the tenth (10th) anniversary of the first commercial sale of mavorixafor, (ii) expiration of regulatory market exclusivity of mavorixafor or (iii) expiration of the last-to-expire licensed patent in such country. The term of the Norgine Agreement shall be automatically renewed for additional three-year terms unless either party provides the other party written notice of its intent not to renew the Norgine Agreement at least one year prior to the applicable termination date of the Norgine Agreement. In the event of automatic renewal, the royalty payment rate drops to a single digit royalty.

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NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

5. Revenue

Product Revenue, Net

During the years ended December 31, 2025 and 2024, the Company recorded net revenue $6.5 million and $2.6 million, respectively, for the sale of its drug product in the U.S. There were no sales of drug product for the year ended December 31, 2023.

The following table summarizes the balances and activity in each of the product reserve accounts for the years ended December 31, 2025 and 2024.

(in thousands) Rebates and Discounts Co-Pay Assistance Product Returns Total

Balance at December 31, 2023 $ — $ — $ — $ —

Credits and payments made during the period (86) (34) — (120)

Credits and payments made during the period (318) (109) — (427)

The provision for contractual discounts provided to the Company’s customer is recorded as a reduction of accounts receivable. The provisions for co-pay assistance payments, contractual rebates and product returns are classified within accrued expenses.

The following table provides a rollforward of accounts receivable for the years ended December 31, 2025 and 2024.

(in thousands) Accounts Receivable

Beginning balance at December 31, 2023 $ —

Increase in accounts receivable for drug product sales 2,735

Decrease in accounts receivable for cash collections (1,665)

Increase in accounts receivable for drug product sales 7,062

Decrease in accounts receivable for cash collections (7,559)

License and Other

During the first quarter of 2025, the Company entered into the Norgine Agreement. The Company analyzed the activities required under the Norgine Agreement and concluded that the arrangement was indicative of a vendor-customer relationship and would be accounted for under ASC 606. During the year ended December 31, 2025, the Company received a one-time, non-refundable, up-front payment of €28.5 million and a regulatory milestone payment of €0.5 million, which are included the transaction price. All other future regulatory-based milestone payments, which represent variable consideration, have been fully constrained as these are not yet considered probable. The Company has also excluded from the transaction price future royalty payments that are based on units sold by Norgine and future cumulative revenue-based milestone payments under the applicable practical expedient.

Under the Norgine Agreement, the Company’s promises include a) the delivery of a license, b) research and development services for certain components of WHIM clinical studies, c) research and development services for the global Phase 3 trial of mavorixafor for CN, and d) the option for delivery of commercial drug supply pursuant to a manufacturing agreement. The Company assessed the above promises and determined that the option for delivery of commercial drug supply is priced at fair value, and therefore is not a material right or a performance obligation. Revenue from the delivery of manufacturing supply will

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NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

be recorded when delivered at the pricing agreed to in the contract. The license was considered functional intellectual property as of the inception of the Norgine Agreement and distinct from other promises under the contract, as Norgine can benefit from the license on its own or together with other readily available resources. Each of the research and development services were considered distinct as the customer can benefit from these services together with the license transferred at the inception of the agreement. The research and development services will not modify or customize the initial intellectual property transferred at contract inception due to the late stage of development of the intellectual property. As a result, the Company identified three performance obligations: (a) the delivery of the license, (b) research and development services for certain components of WHIM clinical studies, and (c) research and development services for the global Phase 3 trial of mavorixafor for CN.

The Company allocated the transaction price of $29.7 million among these three performance obligations based on the Company’s best estimate of stand-alone selling price for each distinct performance obligation. The Company developed the estimated standalone selling price, at inception, for each of the three performance obligations with the objective of determining the price at which the Company would sell such an item if it were to be sold regularly on a standalone basis. The Company developed the estimated standalone selling price for the license primarily based on the probability-weighted present value of expected future cash flows. In developing such estimates, the Company applied judgment in determining the forecasted revenues, taking into consideration the applicable market conditions and relevant entity-specific factors, the probability of success, the time needed to develop mavorixafor and the discount rate. The Company developed the estimated standalone selling price for the research and development services based on the amount a third party would pay for these services, which contemplates the level of efforts necessary to perform these services and the costs for full-time equivalent employees and expected resources to be committed plus a reasonable margin.

During the year ended December 31, 2025, the Company recognized $27.6 million for the delivery of the license and $1.0 million for research and development services. The license performance obligation was satisfied at a point in time upon transfer of the license to Norgine. Control of the license was transferred on the effective date of the Norgine Agreement as Norgine could begin to use and benefit from the license. For the research and development performance obligations, the Company recognizes revenue over time using an input method based on cost incurred during the period relative to the total estimated cost of the obligation. This method, in management’s judgment, is the best measure of progress towards satisfying the performance obligation as the transfer of control occurs as services are performed. The amounts received that have not yet been recognized as revenue are recorded as deferred revenue on the consolidated balance sheet and will be recognized over the remaining period as the performance obligation is satisfied.

The following table summarizes the allocation of transaction price to the three performance obligations in the Norgine Agreement based on the weighting of estimated stand-alone selling price for these performance obligations at the inception of the agreement.

Allocation of Transaction Price Revenue Recognized

(in thousands) Year Ended December 31,

Research and development services: WHIM 312 25 — —

Research and development services: CN 1,724 926 — —

As of December 31, 2025, deferred revenue related to the Norgine Agreement was $1.1 million, of which $0.5 million was current.

During the year ended December 31, 2025, the Company capitalized $4.0 million of incremental costs to obtain a contract with a customer and amortized $3.3 million of these costs through general and administrative expense for the year ended December 31, 2025. No such costs were capitalized or amortized during the years ended December 31, 2024 and 2023. As of December 31, 2025, unamortized capitalized costs to obtain a contract with a customer on the consolidated balance sheet were $0.7 million, of which $0.2 million were classified in other current assets and $0.5 million were classified in other assets.

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NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

6. Fair Value of Financial Assets and Liabilities

The following tables present information about the Company’s financial assets and liabilities measured at fair value on a recurring basis and indicate the level of the fair value hierarchy used to determine such fair values:

Fair Value Measurements as of December 31, 2025 Using:

(in thousands) Level 1 Level 2 Level 3 Total

Assets:

Cash equivalents—money market funds $ 123,838 $ — $ — $ 123,838

Liabilities:

Embedded derivative liability $ — $ — $ 10 $ 10

Class C warrant liability — — 977 977

Fair Value Measurements as of December 31, 2024 Using:

(in thousands) Level 1 Level 2 Level 3 Total

Assets:

Cash equivalents—money market funds $ 40,983 $ — $ — $ 40,983

Liabilities:

Embedded derivative liability $ — $ — $ 10 $ 10

All marketable securities are classified as short-term investments as all are due within one year and include investments in U.S. Treasury notes, U.S. Treasury bills and federal government agency notes. The amortized cost of each investment, individually and in aggregate, approximated fair value. The Company evaluated each marketable security for impairment that is other-than-temporary and concluded that no marketable security was impaired as of December 31, 2025 and December 31, 2024.

The Company’s cash equivalents consisted of money market funds invested in U.S. Treasury securities. The money market funds were valued based on quoted prices in active markets for identical assets, which represents a Level 1 measurement.

The following table provides amortized cost, unrealized gains and losses and the carrying amount of available-for-sale debt marketable securities as of December 31, 2025:

U.S. Treasury securities $ 7,959 $ 3 $ — $ 7,962

Total available-for-sale debt securities $ 35,939 $ 14 $ 4 $ 35,949

The following table provides amortized cost, unrealized gains and losses and the carrying amount of available-for-sale debt marketable securities as of December 31, 2024:

F-21

X4 PHARMACEUTICALS, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

The following table provides a roll-forward for the three years ended December 31, 2025, of the aggregate fair values financial instruments for which fair values are determined using Level 3 inputs:

(in thousands) Embedded Derivative Liability Class C Warrant Liability Total

Reclassification to permanent equity upon exercise — (374) (374)

Valuation of Embedded Derivative Liability—The fair value of the embedded derivative liability recognized in connection with the Company’s Hercules Loan Agreement, which is associated with additional fees due to Hercules upon non-credit related events of default, was determined based on significant inputs not observable in the market, which represents a Level 3 measurement within the fair value hierarchy. The fair value of this embedded derivative liability, which is reported within other non-current liabilities on the consolidated balance sheets, is estimated by the Company at each reporting date based, in part, on the results of third-party valuations, which were prepared based on a discounted cash flow model that considered the timing and probability of occurrence of a redemption upon an event of default, the potential amount of prepayment fees or contingent interest upon an event of default and the Company’s risk-adjusted discount rate of17%.

Class C Warrant Liability— In December 2022, the Company issued Class C Warrants for the purchase of shares of its common stock in a public offering. The Class C Warrants are accounted for as a liability on the consolidated balance sheet and are adjusted to fair value at period end through “change in fair value of warrant liability” on the consolidated statements of operations and comprehensive loss.

The Company calculated the fair value of the Class C Warrants using the Black-Scholes option pricing model, with the following inputs:

Class C Warrants

Risk-free interest rate 3.5 % 4.2 % 3.9 %

Expected term (in years) 1.9 2.9 3.9

Expected dividend yield — % — % — %

Impairment of Goodwill

F-22

X4 PHARMACEUTICALS, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

impairment as of December 31, 2025, 2024 and 2023 and concluded that goodwill was not further impaired. Should the market value of the Company’s common stock decline, impairment charges may be recorded in the future.

The following table provides a rollforward of the Company’s goodwill and accumulated impairment losses.

(in thousands) Goodwill, Gross Accumulated Impairment Loss Goodwill

7. Inventory

Inventory consists of the following:

8. Property and Equipment

Property and equipment, net consisted of the following:

Leasehold improvements $ 228 $ 228

Software — 24

Less: Accumulated depreciation (1,232) (1,903)

Depreciation expense related to property and equipment was $0.5 million, $0.3 million and $0.4 million for the years ended December 31, 2025, 2024 and 2023, respectively.

9. Intangible Assets, Net

As of December 31, 2025, the Company’s net definite-lived intangible asset, which includes the capitalization of certain milestone payments made or accrued related to its license agreement for the intellectual property contained in its drug product, includes a gross intangible asset of $10.5 million, less accumulated amortization of $1.3 million for a net intangible asset of $9.3 million. The Company amortizes the intangible asset to cost of revenue over the remaining life of the underlying patent protecting the intellectual property through 2038.

As of December 31, 2025, amortization expense for the next five years and beyond is summarized as follows:

(in thousands)

Year Amortization expense

F-23

X4 PHARMACEUTICALS, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

The Company began amortizing its finite-lived intangible assets in April 2024 over a 14-year period based on the expected patent exclusivity period for XOLREMDI. Amortization expense totaled $0.8 million and $0.5 million for the years ended December 31, 2025 and 2024, respectively. Amortization expense is recorded as a component of cost of revenue on the consolidated statements of operations and comprehensive loss.

10. Accrued Expenses

Accrued expenses consisted of the following:

Accrued employee compensation and benefits $ 4,303 13,053

Accrued external research and development expenses 12,235 3,727

Accrued royalty and milestone payments 144 3,092

11. Long-Term Debt

Long-term debt consisted of the following:

Principal amount of long-term debt $ 75,000 $ 75,000

Debt discount, net of accretion (412) (650)

Cumulative accrual of end of term payments 1,703 1,075

Hercules Loan Agreement

The Company is party to the Second Amended and Restated Loan and Security Agreement, as amended, (the “Hercules Loan Agreement”) with Hercules, which provides for an aggregate term loan facility of up to $107.5 million, under which the Company has borrowed an aggregate of $75.0 million of term loans, representing the maximum borrowings allowable as of December 31, 2025. Additional borrowings are available subject to approval of the Lender (as defined in the Hercules Loan Agreement) in its sole discretion.

Borrowings under the Hercules Loan Agreement accrue interest at a variable rate equal to the greater of (i) 10.15% or (ii) The Wall Street Journal prime rate plus 3.15%. In an event of default and until such event is no longer continuing, the interest rate applicable to borrowings would be increased by 4.0%. Borrowings are repayable in monthly interest-only payments through July 1, 2027, which is the maturity date of the Hercules Loan Agreement. At the Company’s option, the Company may prepay all, but not less than all, of the outstanding borrowings, subject to a prepayment premium of 1%. In addition, the Hercules Loan Agreement provides for payment of end-of-term fees of $2.8 million plus 3.5% of the aggregate principal amount of loans drawn, if any, subsequent to the most recent amendment in August 2023, payable upon the earlier of maturity or the repayment in full of all obligations under the Hercules Loan Agreement. Borrowings under the Hercules Loan Agreement are

F-24

X4 PHARMACEUTICALS, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

collateralized by substantially all of the Company’s personal property and other assets except for its intellectual property (but including rights to payment and proceeds from the sale, licensing or disposition of the intellectual property).

Under the Hercules Loan Agreement, the Company has agreed to affirmative and negative covenants. The Company must maintain cash, cash equivalents or liquid assets in an account or accounts in which Hercules has a first priority security interest (“Qualified Cash”) in an aggregate amount equal to at least 20% of the aggregate principal amount of loans outstanding under the Hercules Loan Agreement, which equals $15.0 million as of the issuance of these consolidated financial statements. The Company must also continue to achieve a performance covenant, which includes maintaining a trailing six-month net product revenue of at least 55% of its forecast as approved by the Company’s Board of Directors (the “Performance Covenant”). Such Performance Covenant is waived during any period in which:

(i.) the Company maintains Qualified Cash, as defined in the Hercules Loan Agreement, in an aggregate amount equal to at least 75% of loans outstanding under the Hercules Loan Agreement or

(ii.) both (x.) the Company maintains a Market Capitalization (as defined in the Hercules Loan Agreement) of at least $450.0 million and (y.) the Company maintains Qualified Cash in an aggregate amount equal to at least 45% of loans outstanding.

The Hercules Loan Agreement also restricts the Company’s ability to incur additional indebtedness, pay dividends, encumber its intellectual property, or engage in certain fundamental business transactions, such as mergers or acquisitions of other businesses, with certain exceptions.

The Company recognized interest expense under the Hercules Loan Agreement as follows:

(in thousands) Year Ended December 31,

The annual effective interest rate on the Hercules Loan Agreement as of December 31, 2025 was 11.2%. There were no principal payments due or paid under the Hercules Loan Agreement during the years ended December 31, 2025 and 2024.

As of December 31, 2025, future principal and accrued end-of-term payments of $76.7 million under the Hercules Loan Agreement are due on July 1, 2027.

(in thousands),

Year Ending December 31, Total

Long-term debt, including end-of-term payments $ 76,703

12. Leases

The Company has a lease agreement for its facilities in Boston, Massachusetts, which is the Company’s principal executive offices, and previously had a lease in Vienna, Austria (the “Vienna Lease”), which was previously the Company’s research and development center. There are no restrictions or financial covenants associated with any of the lease agreements.

Boston Lease— The Company leases approximately 28,000 square feet of office space in Boston, Massachusetts (“Boston Lease”), which serves as the Company’s headquarters. Base rental payments are approximately $1.1 million annually, plus certain operating expenses. The term of the Boston Lease will continue until November 2026, unless earlier terminated. The Company is required to maintain a security deposit in the form of a letter of credit for $0.6 million for the benefit of the landlord.

F-25

X4 PHARMACEUTICALS, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

Vienna Austria Lease—The Company had an operating lease for approximately 1,200 square meters of laboratory and office space in Vienna, Austria that commenced in February 2021 for a term of seven years. Effective November 30, 2025, the Company terminated the Vienna Lease in accordance with a lease amendment entered into with the landlord. Accordingly, the Company accelerated the amortization of the right-of-use asset to zero and adjusted the remaining lease obligation to zero as of December 31, 2025.

The components of lease expense for the years ended December 31, 2025, 2024 and 2023 were as follows:

(dollars in thousands) Year Ended December 31,

Other information

Sublease income $ — $ — $ 195

Operating cash outflows from operating leases $ 1,398 $ 1,377 $ 1,385

Weighted-average remaining lease term 0.9 years 2.3 years 3.2 years

Weighted-average discount rate 11.5 % 11.5 % 11.5 %

Maturities of lease liabilities due under lease agreements as of December 31, 2025 are as follows (in thousands):

Maturity of lease liabilities OperatingLeases

XFOR US Equity

XFOR · 10-K · period ended 2025-12-31

Item 7. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

Item 7A. Quantitative and Qualitative Disclosures About Market Risk

Item 8. Financial Statements and Supplementary Data

Item 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosures

Item 9A. Controls and Procedures

Item 9B. Other Information

Item 9C. Disclosure Regarding Foreign Jurisdictions That Prevent Inspections

Item 10. Directors, Executive Officers and Corporate Governance

Item 11. Executive Compensation

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

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

Item 14. Principal Accountant Fees and Services

Item 15. Exhibit and Financial Statement Schedules

Item 16. Form 10-K Summary

XFOR US Equity☆

XFOR · 10-K · period ended 2025-12-31

Item 7. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

Item 7A. Quantitative and Qualitative Disclosures About Market Risk

Item 8. Financial Statements and Supplementary Data

Item 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosures

Item 9A. Controls and Procedures

Item 9B. Other Information

Item 9C. Disclosure Regarding Foreign Jurisdictions That Prevent Inspections

Item 10. Directors, Executive Officers and Corporate Governance

Item 11. Executive Compensation

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

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

Item 14. Principal Accountant Fees and Services

Item 15. Exhibit and Financial Statement Schedules

Item 16. Form 10-K Summary

XFOR US Equity