Limited Assurance Report of the Independent Auditor on the Sustainability Statement

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

Our conclusion

We have performed a limited assurance engagement on the consolidated sustainability statement for the year ended December 31, 2025 of argenx SE based in Amsterdam (hereinafter: the company) in section 7 ‘Non-Financial information’ of the accompanying management report including the information incorporated in the sustainability statement by reference (hereinafter: the sustainability statement).

Based on our procedures performed and the evidence obtained, nothing has come to our attention that causes us to believe that the sustainability statement is not, in all material respects:

• prepared in accordance with the European Sustainability Reporting Standards (ESRS) as adopted by the European Commission and compliant with the double materiality assessment process carried out by the company to identify the information reported pursuant to the ESRS; and
• compliant with the reporting requirements provided for in Article 8 of Regulation (EU) 2020/852 (Taxonomy Regulation).

Our conclusion has been formed on the basis of the matters outlined in this limited assurance report

Basis for our conclusion

We have performed our limited assurance engagement on the sustainability statement in accordance with Dutch law, including Dutch Standard 3810N, “Assurance-opdrachten inzake duurzaamheidsverslaggeving” (Assurance engagements relating to sustainability reporting), which is a specified Dutch standard that is based on the International Standard on Assurance Engagements (ISAE) 3000 (Revised), “Assurance engagements other than audits or reviews of historical financial information”.

Our assurance engagement was aimed to obtain a limited level of assurance that the sustainability statement is free from material misstatements. The procedures vary in nature and timing from, and are less in extent, than for a reasonable assurance engagement. Consequently, the level of assurance obtained in a limited assurance engagement is substantially lower than the assurance that would have been obtained had a reasonable assurance engagement been performed.

Our responsibilities in this regard are further described in the section ‘Our responsibilities for the limited assurance engagement on the sustainability statement’ of our report.

We are independent of argenx SE in accordance with 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. This includes that we do not perform any activities that could result in a conflict of interest with our independent assurance engagement and we are not involved in the preparation of the sustainability statement, as doing so may compromise our independence. Furthermore, we have complied with the Verordening gedrags- en beroepsregels accountants (VGBA, Dutch Code of Ethics for Professional Accountants). The ViO and VGBA are at least as demanding as the International code of ethics for professional accountants (including International independence standards) of the International Ethics Standards Board for Accountants (the IESBA Code) as relevant to limited assurance engagements on sustainability statements of public interest entities in the European Union.

We believe that the assurance evidence we have obtained is sufficient and appropriate to provide a basis for our conclusion.

Inherent limitations associated with measurement or evaluation of sustainability information

Significant uncertainties affecting the quantitative metrics and monetary amounts

Section 7.1.2.2 “Disclosures in relation to specific circumstances” in the sustainability statement identifies the quantitative metrics and monetary amounts that are subject to a high level of measurement uncertainty and discloses information about the sources of measurement uncertainty and the assumptions, approximations and judgments the company has made in measuring these in compliance with the ESRS.

Comparability may be limited for entity-specific sustainability information

The company provides additional entity-specific sustainability information in Section 7.3.2 “S4 Patients”. The comparability of entity-specific sustainability information between entities and over time may be affected by the absence of a uniform practice or availability of external information sources to measure or evaluate this information that can support comparability. This allows for the application of different, but acceptable, measurement techniques.

Inherent limitations of a double materiality assessment process

The sustainability statement may not include every impact, risk and opportunity or additional entity-specific disclosure that each individual stakeholder (group) may consider important in its own particular assessment.

Inherent limitations of forward-looking information

In reporting forward-looking information in accordance with the ESRS, management describes the underlying assumptions and methods of producing the information, as well as other factors that provide evidence that it reflects the actual plans or decisions made by the company (actions). Forward-looking information relates to events and actions that have not yet occurred and may never occur. The actual outcome is likely to be different since anticipated events frequently do not occur as expected.

Responsibilities of the Board of Directors for the sustainability statement

The executive directors of the Board of Directors are responsible for the preparation of the sustainability statement in accordance with the ESRS, including the double materiality assessment process carried out by the company as the basis for the sustainability statement and disclosure of material impacts, risks and opportunities in accordance with the ESRS. As part of the preparation of the sustainability statement, the executive directors are responsible for compliance with the reporting requirements provided for in Article 8 of Regulation (EU) 2020/852 (Taxonomy Regulation).

The executive directors are also responsible for selecting and applying additional entity-specific disclosures to enable users to understand the company’s sustainability-related impacts, risks or opportunities and for determining that these additional entity-specific disclosures are suitable in the circumstances and in accordance with the ESRS.

Furthermore, the executive directors are responsible for such internal control as they determine is necessary to enable the preparation of the sustainability statement that is free from material misstatement, whether due to fraud or error.

The non-executive directors of the Board of Directors are responsible for overseeing the sustainability reporting process including the double materiality assessment process carried out by the company.

Our responsibilities for the limited assurance engagement on the Sustainability Statement

Our responsibility is to plan and perform the limited assurance engagement in a manner that allows us to obtain sufficient and appropriate assurance evidence for our conclusion.

We apply the applicable quality management requirements pursuant to the Nadere voorschriften kwaliteitsmanagement (NVKM, regulations for quality management) and the International Standard on Quality Management (ISQM) 1, and accordingly maintain a comprehensive system of quality management including documented policies and procedures regarding compliance with ethical requirements, professional standards and other relevant legal and regulatory requirements.

Our limited assurance engagement included amongst others:

• Performing inquiries and an analysis of the external environment and obtaining an understanding of relevant sustainability themes and issues, the characteristics of the company, its activities and the value chain and its key intangible resources in order to assess the double materiality assessment process carried out by the company as the basis for the sustainability statement and disclosure of all material sustainability-related impacts, risks and opportunities in accordance with the ESRS.
• Obtaining through inquiries a general understanding of the internal control environment, the company’s processes for gathering and reporting entity-related and value chain information, the information systems and the company’s risk assessment process relevant to the preparation of the sustainability statement and for identifying the company’s activities, determining eligible and aligned economic activities and prepare the disclosures provided for in Article 8 of Regulation (EU) 2020/852 (Taxonomy Regulation), without obtaining assurance information about the implementation or testing the operating effectiveness of controls.
• Assessing the double materiality assessment process carried out by the company and identifying and assessing areas of the sustainability statement, including the disclosures provided for in Article 8 of Regulation (EU) 2020/852 (Taxonomy Regulation), where misleading or unbalanced information or material misstatements, whether due to fraud or error, are likely to arise (‘selected disclosures’). Designing and performing further assurance procedures aimed at assessing that the sustainability statement is free from material misstatements responsive to this risk analysis.
• Considering whether the description of the double materiality assessment process in the sustainability statement made by the Board of Directors appears consistent with the process carried out by the company.
• Performing analytical review procedures on quantitative information in the sustainability statement, including consideration of data and trends.
• Assessing whether the company’s methods for developing estimates are appropriate and have been consistently applied for selected disclosures. We considered data and trends, however our procedures did not include testing the data on which the estimates are based or separately developing our own estimates against which to evaluate the Board of Director’s estimates.
• Analyzing, on a limited sample basis, relevant internal and external documentation available to the company (including publicly available information or information from actors throughout its value chain) for selected disclosures.
• Reading the other information in the annual report to identify material inconsistencies, if any, with the sustainability statement.
• Considering whether the disclosures provided to address the reporting requirements provided for in Article 8 of Regulation (EU) 2020/852 (Taxonomy Regulation) for each of the environmental objectives, reconcile with the underlying records of the company and are consistent or coherent with the sustainability statement, appear reasonable, in particular whether the eligible economic activities meet the cumulative conditions to qualify as aligned and whether the technical screening criteria are met, and whether the key performance indicators disclosures have been defined and calculated in accordance with the Taxonomy delegated acts, and comply with the reporting requirements provided for in Article 8 of Regulation (EU) 2020/852 (Taxonomy Regulation), including the format in which the activities are presented.
• Considering the overall presentation, structure and fundamental qualitative characteristics of information (relevance and faithful representation: complete, neutral and accurate) reported in the sustainability statement, including the reporting requirements provided for in Article 8 of Regulation (EU) 2020/852 (Taxonomy Regulation).
• Considering, based on our limited assurance procedures and evaluation of the evidence obtained, whether the sustainability statement as a whole, is free from material misstatements and prepared in accordance with the ESRS.

Communication

We communicate with the Board of Directors regarding, among other matters, the planned scope and timing of the assurance engagement and significant findings that we identify during our assurance engagement.

Eindhoven, March 19, 2026
EY Accountants B.V.

signed by J.C.F. Lemmens