Xenon Pharmaceuticals Announces Proposed Public Offering

VANCOUVER, British Columbia and BOSTON, MA, March 09, 2026 (GLOBE NEWSWIRE) -- Xenon Pharmaceuticals Inc. (Nasdaq: XENE), a neuroscience-focused biopharmaceutical company dedicated to drug discovery, clinical development and commercialization of life-changing therapeutics for patients in need, today announced that it has commenced an underwritten public offering of $500.0 million of its common shares, pursuant to its existing shelf registration statement. All of the common shares in this offering are being offered by Xenon. In addition, Xenon intends to grant the underwriters an option for a period of 30 days to purchase up to an additional $75.0 million of common shares at the public offering price, less the underwriting discounts and commissions. The proposed offering is subject to market and other conditions, and there can be no assurance as to whether or when the offering may be completed.

J.P. Morgan, Jefferies, TD Cowen, Stifel, RBC Capital Markets, and William Blair are acting as joint book-running managers for the proposed offering. Baird is acting as lead manager for the proposed offering.

No securities are being offered or sold, directly or indirectly, in Canada or to any resident of Canada.

This press release shall not constitute an offer to sell or the solicitation of an offer to buy the securities being offered, nor shall there be any sale of the securities being offered in any state or other jurisdiction in which such offer, solicitation or sale would be unlawful prior to the registration or qualification under the securities laws of any such state or other jurisdiction.

Safe Harbor Statement
This press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934 and the Private Securities Litigation Reform Act of 1995 and Canadian securities laws. These forward-looking statements are not based on historical fact and include statements regarding the anticipated public offering. These forward-looking statements are based on current assumptions that involve risks, uncertainties and other factors that may cause the actual results, events or developments to be materially different from those expressed or implied by such forward-looking statements. These risks and uncertainties, many of which are beyond our control, include, but are not limited to, uncertainties related to market conditions and the completion of the public offering on the anticipated terms or at all; the grant to the underwriters of the option to purchase additional shares; the impact of unstable economic conditions in the general domestic and global economic markets; adverse conditions from geopolitical events; as well as the other risks identified in our filings with the SEC and the securities commissions in British Columbia, Alberta and Ontario. These forward-looking statements speak only as of the date hereof and we assume no obligation to update these forward-looking statements, and readers are cautioned not to place undue reliance on such forward-looking statements.

About Xenon Pharmaceuticals Inc.

Xenon Pharmaceuticals (Nasdaq: XENE) is a neuroscience-focused biopharmaceutical company dedicated to drug discovery, clinical development and commercialization of life-changing therapeutics for patients in need. Xenon’s lead molecule, azetukalner, is a novel, potent K

7 potassium channel opener in Phase 3 clinical trials for the treatment of epilepsy, major depressive disorder (MDD) and bipolar depression (BPD). Xenon is also advancing an early-stage portfolio of multiple promising potassium and sodium channel modulators, including K 7 and Na 1.7 programs in Phase 1 development for the potential treatment of pain. Xenon has offices in Vancouver, British Columbia, and Boston, Massachusetts.

Xenon and the Xenon logo are registered trademarks or trademarks of Xenon Pharmaceuticals Inc. in the US, Canada, and elsewhere. All other trademarks belong to their respective owner.