These unaudited interim condensed consolidated financial statements are presented in U.S. dollars and include the accounts of the Company and its wholly-owned subsidiary, Xenon Pharmaceuticals USA Inc., a Delaware corporation. All intercompany transactions and balances have been eliminated on consolidation.

The accompanying unaudited interim condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) and pursuant to the rules and regulations of the United States Securities and Exchange Commission (“SEC”) for interim financial information. Certain information has been reclassified to conform with the financial presentation adopted for the current year. Accordingly, these condensed consolidated financial statements do not include all of the information and footnotes required for complete consolidated financial statements and should be read in conjunction with the audited consolidated financial statements and notes for the year ended December 31, 2025 included in the Company’s 2025 Annual Report on Form 10-K filed with the SEC and with the securities commissions in British Columbia, Alberta and Ontario on February 26, 2026.

These unaudited interim condensed consolidated financial statements reflect all adjustments, consisting of normal recurring adjustments, which, in the opinion of management, are necessary for a fair presentation of results for the interim periods presented. The results of operations for the three and six month periods ended June 30, 2026 and 2025 are not necessarily indicative of results that can be expected for a full year. These unaudited interim condensed consolidated financial statements follow the same significant accounting policies as those described in the notes to the audited consolidated financial statements of the Company included in the Company’s 2025 Annual Report on Form 10-K for the year ended December 31, 2025, with the exception of the policy described in note 3 below.