Independent Auditor’s Report

To: the Shareholders and the Board of Directors of argenx SE

Report on the Audit of the Financial Statements 2022 Included in the Annual Report

Our Opinion

We have audited the financial statements 2022 of argenx SE, based in Amsterdam, the Netherlands. The financial statements comprise the consolidated financial statements and the company financial statements.

In our opinion:

• The accompanying consolidated financial statements give a true and fair view of the financial position of argenx SE as at December 31 2022, and of its result and its cash flows for 2022 in accordance with International Financial Reporting Standards as adopted by the European Union (EU-IFRS) and with Part 9 of Book 2 of the Dutch Civil Code.
• The accompanying company financial statements give a true and fair view of the financial position of argenx SE as at December 31 2022, and of its result for 2022 in accordance with Part 9 of Book 2 of the Dutch Civil Code.

The consolidated financial statements comprise:

1. The consolidated statements of financial position as at December 31 2022.
2. The following statements for 2022: the consolidated statements of profit or loss, the consolidated statements of comprehensive income and loss, the consolidated statements of cash flows and the consolidated statements of changes in equity.
3. The notes comprising a summary of the significant accounting policies and other explanatory information.

The company financial statements comprise:

1. The company balance sheet as at December 31 2022.
2. The company profit and loss account for 2022.
3. The notes comprising a summary of the significant accounting policies and other explanatory information.

Basis for our Opinion

We conducted our audit in accordance with Dutch law, including the Dutch Standards on Auditing. Our responsibilities under those standards are further described in the 'Our responsibilities for the audit of the financial statements' section of our report.

We are independent of argenx SE in accordance with the EU Regulation on specific requirements regarding statutory audit of public-interest entities, the Wet toezicht accountantsorganisaties (Wta, Audit firms supervision act), the Verordening inzake de onafhankelijkheid van accountants bij assurance-opdrachten (ViO, Code of Ethics for Professional Accountants, a regulation with respect to independence) and other relevant independence regulations in the Netherlands. Furthermore, we have complied with the Verordening gedrags- en beroepsregels accountants (VGBA, Dutch Code of Ethics).

We believe the audit evidence we have obtained is sufficient and appropriate to provide a basis for our opinion.

Information in Support of our Opinion

We designed our audit procedures in the context of our audit of the financial statements as a whole and in forming our opinion thereon. The following information in support of our opinion was addressed in this context, and we do not provide a separate opinion or conclusion on these matters.

Materiality

Based on our professional judgement we determined the materiality for the financial statements as a whole at USD 39,700,000. The materiality is based on 3.5% of operating expenses excluding cost of sales and excluding the loss in joint venture. We have also taken into account misstatements and/or possible misstatements that in our opinion are material for the users of the financial statements for qualitative reasons.

We agreed with the Board of Directors that misstatements in excess of USD 1,985,000, which are identified during the audit, would be reported to them, as well as smaller misstatements that in our view must be reported on qualitative grounds.

Scope of the Group Audit

argenx SE is at the head of a group of entities. The financial information of this group is included in the consolidated financial statements of argenx SE.

Because we are ultimately responsible for the opinion, we are also responsible for directing, supervising and performing the group audit. In this respect we have determined the nature and extent of the audit procedures to be carried out for group entities. The audit procedures on all group entities have been performed by the group engagement team.

By performing the procedures mentioned above at group entities, together with additional procedures at group level, we have been able to obtain sufficient and appropriate audit evidence about the group’s financial information to provide an opinion on the consolidated financial statements.

Audit Approach Fraud Risks

We identified and assessed the risks of material misstatements of the financial statements due to fraud. During our audit we obtained an understanding of the entity and its environment and the components of the system of internal control, including the risk assessment process and management’s process for responding to the risks of fraud and monitoring the system of internal control and how the Board of Directors exercises oversight, as well as the outcomes.

We evaluated the design and relevant aspects of the system of internal control and in particular the fraud risk assessment, as well as among others the code of conduct, whistle blower procedures and incident registration. We evaluated the design and the implementation and, where considered appropriate, tested the operating effectiveness, of internal controls designed to mitigate fraud risks.

As part of our process of identifying fraud risks, we evaluated fraud risk factors with respect to financial reporting fraud, misappropriation of assets and bribery and corruption in close co-operation with our forensic specialists. We evaluated whether these factors indicate that a risk of material misstatement due to fraud is present.

We identified the following fraud risk and performed the following specific procedures:

• We identified a risk of material misstatement due to fraud related to management override of controls. Management is in a unique position to perpetrate fraud because of management’s ability to manipulate accounting records and prepare fraudulent financial statements by overriding controls that otherwise appear to be operating effectively.
• We incorporated elements of unpredictability in our audit. We also considered the outcome of our other audit procedures and evaluated whether any findings were indicative of fraud or non-compliance.
• We considered available information and made enquiries of relevant management team members (including the Chief Executive Officer, Chief Operating Officer, Chief Financial Officer, General Counsel, Global Head of Quality, Global Head of Compliance, and Chief Medical Officer) and the Board of Directors.
• We tested the appropriateness of journal entries recorded in the general ledger and other adjustments made in the preparation of the financial statements.
• We evaluated whether the selection and application of accounting policies by the group, particularly those related to subjective measurements and complex transactions, may be indicative of fraudulent financial reporting.
• We evaluated whether the judgments and decisions made by management in making the accounting estimates included in the financial statements indicate a possible bias that may represent a risk of material misstatement due to fraud. Management insights, estimates and assumptions that might have a major impact on the financial statements are disclosed in note 3. Critical accounting estimates and judgments of the financial statements. Reference is made to the section 'Our key audit matters'.
• For significant transactions and transactions of interest, for instance regarding donations to patient charities, we evaluated whether the business rationale of the transactions suggests that they may have been entered into to engage in activities in relation to bribery and corruption.

This did not lead to indications for fraud potentially resulting in material misstatements.

Audit Approach Compliance with Laws and Regulations

We assessed the laws and regulations relevant to the Company through discussion with the General Counsel, the Head of Global Quality and the Head of Global Compliance, reading minutes and reports of internal audit.

We involved our forensic specialists in this evaluation.

As a result of our risk assessment procedures, and while realizing that the effects from non-compliance could considerably vary, we considered the following laws and regulations: adherence to (corporate) tax law and financial reporting regulations, the requirements under the International Financial Reporting Standards as adopted by the European Union (EU-IFRS) and Part 9 of Book 2 of the Dutch Civil Code with a direct effect on the financial statements as an integrated part of our audit procedures, to the extent material for the related financial statements.

We obtained sufficient appropriate audit evidence regarding provisions of those laws and regulations generally recognized to have a direct effect on the financial statements.

Apart from these, argenx SE is subject to other laws and regulations where the consequences of non- compliance could have a material effect on amounts and/or disclosures in the financial statements, for instance, through imposing fines or litigation.

Given the nature of argenx SE’s business and the complexity of FDA regulations and other healthcare authority regulations, there is a risk of non-compliance with the requirements of such laws and regulations. In addition, we considered major laws and regulations applicable to listed companies.

Our procedures are more limited with respect to these laws and regulations that do not have a direct effect on the determination of the amounts and disclosures in the financial statements. Compliance with these laws and regulations may be fundamental to the operating aspects of the business, to argenx SE’s ability to continue its business, or to avoid material penalties (e.g., compliance with healthcare regulations) and therefore non-compliance with such laws and regulations may have a material effect on the financial statements. Our responsibility is limited to undertaking specified audit procedures to help identify non- compliance with those laws and regulations that may have a material effect on the financial statements. Our procedures are limited to (i) inquiry of management, the Board of Directors and others within argenx SE as to whether argenx SE is in compliance with such laws and regulations and (ii) inspecting correspondence, if any, with the relevant licensing or regulatory authorities to help identify non-compliance with those laws and regulations that may have a material effect on the financial statements.

Naturally, we remained alert to indications of (suspected) non-compliance throughout the audit.

Finally, we obtained written representations that all known instances of (suspected) fraud or non-compliance with laws and regulations have been disclosed to us.

Audit Approach Going Concern

As explained in the note 2.1 “Statement of compliance and basis of preparation” and note 26 “Financial risk management” of the financial statements, management has prepared the financial statements of argenx SE based on the going concern assumption. No events or circumstances have been identified which cause significant doubt about the entity’s ability to continue its operations (going concern risks). Our procedures to evaluate the going concern assessment of management include:

• Consider whether management’s assessment of going concern contains all relevant information of which we are aware as a result of our audit and review of the other information. In addition, we inquired with management about the key assumptions underlying the going concern assessment.
• Inquiry with management regarding their knowledge of events and/or circumstances beyond the period of management’s assessment.
• We reconciled the cash and cash equivalents position as used in the going concern assessment to the audited position at December 31, 2022.
• We evaluated managements’ financial forecasts and analysis prepared for a period of at least 12 months from the date of preparation of the financial statements. This included consideration of the reasonableness of key underlying assumptions by evaluating historically realized and future expected operating and capital expenditure as well as evaluating mathematical accuracy of the assessment.
• We evaluated the adequacy of disclosures made in the financial statements in respect of going concern.

Our audit procedures did not produce results that were inconsistent with management’s assumptions and judgments in applying the going concern assumption.

Our Key Audit Matters

Key audit matters are those matters that, in our professional judgement, were of most significance in our audit of the financial statements. We have communicated the key audit matters to the Board of Directors. The key audit matters are not a comprehensive reflection of all matters discussed.

Product Net Sales — Refer to Note 15 & 18 to the Financial Statements

Description

The Company recognizes product net sales of USD 400.7 million, relating to the sale of their product VYVGART, as specified in note 15 and 18 to the financial statements. These product sales are accounted for in accordance with IFRS 15 Revenue from Contracts with Customers (IFRS 15), whereby the sale of VYVGART to customers is recognized for an amount that reflects the consideration to which the Company expects to be entitled in exchange for these goods. The majority of the product gross sales are in the United States of America, which are subject to various deductions which are primarily composed of rebates to government agencies, distributors, health insurance companies and managed healthcare organizations.

Together, these deductions are referred to as gross-to-net (GtN) adjustments. The GtN adjustments that are recognized by the Company represent estimates of the related obligations that will be settled in a future period. The estimated amounts are based on contractual arrangements with healthcare authorities, government and state programs, and gross sales and third-party data.

We identified the GtN adjustments for product net sales in the United States of America as a key audit matter, because of the significant effort spent on auditing these adjustments and the judgment required to obtain sufficient appropriate audit evidence that supports the Company’s estimate, due to the reporting data being subject to a time lag.

Our response

Our audit procedures related to the gross-to-net included the following, among others:

• We evaluated the key revenue contracts and supply chain contracts, including evaluation of the accounting treatment of the GtN adjustments and the disclosures thereof in accordance with IFRS 15.
• We evaluated the independent service auditor reports for the service providers used by the Company to process rebates on behalf of the Company.
• We evaluated the Company’s methodology and assumptions in developing the GtN adjustments, including testing the completeness and accuracy of the underlying data used by management in their estimates.
• We evaluated the Company’s ability to estimate the GtN adjustments by evaluating the historical accuracy of estimates made during the year.

Observations

The scope and nature of the audit procedures we performed was sufficient and appropriate to address the risks of material misstatement related to the GtN adjustments.

In comparison with prior year, we have not included the key audit matters around the R&D accruals and the accounting treatment of the Zai collaboration. The complexity of the estimates related to the R&D accruals decreased as a result of a change in internal processes. The accounting treatment of the Zai collaboration was related to the initial accounting treatment and as such was no longer identified as a key audit matter.

Report on the Other Information Included in The Annual Report

The Annual Report contains other information, in addition to the financial statements and our auditor’s report thereon.

The other information consists of:

• Management’s Report, including, amongst others, the Remuneration Report and Compensation Statement, and Non-Financial Information.
• Other Information as required by Part 9 of Book 2 of the Dutch Civil Code.

Based on the following procedures performed, we conclude that the other information:

• Is consistent with the financial statements and does not contain material misstatements.
• Contains all the information regarding the management report and the other information as required by Part 9 of Book 2 of the Dutch Civil Code.

We have read the other information. Based on our knowledge and understanding obtained through our audit of the financial statements or otherwise, we have considered whether the other information contains material misstatements.

By performing these procedures, we comply with the requirements of Part 9 of Book 2 of the Dutch Civil Code and the Dutch Standard 720. The scope of the procedures performed is substantially less than the scope of those performed in our audit of the financial statements.

Management is responsible for the preparation of the other information, including Management’s Report in accordance with Part 9 of Book 2 of the Dutch Civil Code, and the other information as required by Part 9 of Book 2 of the Dutch Civil Code.

Report on Other Legal and Regulatory Requirements and ESEF

Engagement

We were engaged by the Board of Directors as auditor of argenx SE on May 13, 2015, as of the audit for the year 2015 and have operated as statutory auditor ever since that financial year.

No Prohibited Non-Audit Services

We have not provided prohibited non-audit services as referred to in Article 5(1) of the EU Regulation on specific requirements regarding statutory audit of public-interest entities.

European Single Electronic Format (ESEF)

argenx SE has prepared its annual report in ESEF. The requirements for this are set out in the Commission Delegated Regulation (EU) 2019/815 with regard to regulatory technical standards on the specification of a single electronic reporting format (hereinafter: the RTS on ESEF).

In our opinion, the annual report, prepared in XHTML format, including the (partly) marked-up consolidated financial statements, as included in the reporting package by argenx SE complies in all material respects with the RTS on ESEF.

Management is responsible for preparing the annual report including the financial statements in accordance with the RTS on ESEF, whereby management combines the various components into a single reporting package.

Our responsibility is to obtain reasonable assurance for our opinion whether the annual report in this reporting package complies with the RTS on ESEF.

We performed our examination in accordance with Dutch law, including Dutch Standard 3950N ‘Assurance- opdrachten inzake het voldoen aan de criteria voor het opstellen van een digitaal verantwoordingsdocument’ (assurance engagements relating to compliance with criteria for digital reporting).

Our examination included amongst others:

• Obtaining an understanding of the company’s financial reporting process, including the preparation of the reporting package.
• Identifying and assessing the risks that the annual report does not comply in all material respects with the RTS on ESEF and designing and performing further assurance procedures responsive to those risks to provide a basis for our opinion, including:
  • obtaining the reporting package and performing validations to determine whether the reporting package containing the Inline XBRL instance and the XBRL extension taxonomy files has been prepared in accordance with the technical specifications as included in the RTS on ESEF;
  • examining the information related to the consolidated financial statements in the reporting package to determine whether all required mark-ups have been applied and whether these are in accordance with the RTS on ESEF.

Description of Responsibilities Regarding the Financial Statements

Responsibilities of Management and the Board of Directors for the Financial Statements

Management is responsible for the preparation and fair presentation of the financial statements in accordance with EU-IFRS and Part 9 of Book 2 of the Dutch Civil Code. Furthermore, management is responsible for such internal control as management determines is necessary to enable the preparation of the financial statements that are free from material misstatement, whether due to fraud or error.

As part of the preparation of the financial statements, management is responsible for assessing the company’s ability to continue as a going concern. Based on the financial reporting frameworks mentioned, management should prepare the financial statements using the going concern basis of accounting unless management either intends to liquidate the company or to cease operations, or has no realistic alternative but to do so.

Management should disclose events and circumstances that may cast significant doubt on the company’s ability to continue as a going concern in the financial statements.

The Board of Directors is responsible for overseeing the company’s financial reporting process.

Our Responsibilities for the Audit of the Financial Statements

Our objective is to plan and perform the audit assignment in a manner that allows us to obtain sufficient and appropriate audit evidence for our opinion.

Our audit has been performed with a high, but not absolute, level of assurance, which means we may not detect all material errors and fraud during our audit.

Misstatements can arise from fraud or error and are considered material if, individually or in the aggregate, they could reasonably be expected to influence the economic decisions of users taken on the basis of these financial statements. The materiality affects the nature, timing and extent of our audit procedures and the evaluation of the effect of identified misstatements on our opinion.

We have exercised professional judgement and have maintained professional scepticism throughout the audit, in accordance with Dutch Standards on Auditing, ethical requirements and independence requirements. Our audit included among others:

• Identifying and assessing the risks of material misstatement of the financial statements, whether due to fraud or error, designing and performing audit procedures responsive to those risks, and obtaining audit evidence that is sufficient and appropriate to provide a basis for our opinion. The risk of not detecting a material misstatement resulting from fraud is higher than for one resulting from error, as fraud may involve collusion, forgery, intentional omissions, misrepresentations, or the override of internal control.
• Obtaining an understanding of internal control relevant to the audit in order to design audit procedures that are appropriate in the circumstances, but not for the purpose of expressing an opinion on the effectiveness of the company’s internal control.
• Evaluating the appropriateness of accounting policies used and the reasonableness of accounting estimates and related disclosures made by management.
• Concluding on the appropriateness of management’s use of the going concern basis of accounting, and based on the audit evidence obtained, whether a material uncertainty exists related to events or conditions that may cast significant doubt on the company’s ability to continue as a going concern. If we conclude that a material uncertainty exists, we are required to draw attention in our auditor’s report to the related disclosures in the financial statements or, if such disclosures are inadequate, to modify our opinion. Our conclusions are based on the audit evidence obtained up to the date of our auditor’s report. However, future events or conditions may cause the company to cease to continue as a going concern.
• Evaluating the overall presentation, structure and content of the financial statements, including the disclosures.
• Evaluating whether the financial statements represent the underlying transactions and events in a manner that achieves fair presentation.

Because we are ultimately responsible for the opinion, we are also responsible for directing, supervising and performing the group audit. In this respect we have determined the nature and extent of the audit procedures to be carried out for group entities. Decisive were the size and/or the risk profile of the group entities or operations. On this basis, we selected group entities for which an audit or review had to be carried out on the complete set of financial information or specific items.

We communicate with the Board of Directors regarding, among other matters, the planned scope and timing of the audit and significant audit findings, including any significant findings in internal control that we identified during our audit. In this respect we also submit an additional report to the audit committee in accordance with Article 11 of the EU Regulation on specific requirements regarding statutory audit of public- interest entities. The information included in this additional report is consistent with our audit opinion in this auditor’s report.

We provide the Board of Directors with a statement that we have complied with relevant ethical requirements regarding independence, and to communicate with them all relationships and other matters that may reasonably be thought to bear on our independence, and where applicable, related safeguards.

From the matters communicated with the Board of Directors, we determine the key audit matters: those matters that were of most significance in the audit of the financial statements. We describe these matters in our auditor’s report unless law or regulation precludes public disclosure about the matter or when, in extremely rare circumstances, not communicating the matter is in the public interest.

Rotterdam, March 16, 2023
Deloitte Accountants B.V.
V. Fruytier