Vancouver, British Columbia--(Newsfile Corp. - November 6, 2025) - Sienna Resources Inc. (TSXV: SIEN) (FSE: A418KR) (the "Company" or "Sienna") wishes to provide an update to its shareholders on the impact of the current delays and suspension of mail service in Canada as a result of the nationwide strike of the Canadian Union of Postal Workers as it relates to the requirements to send proxy materials (the "Meeting Materials") for the Company's upcoming annual general & special meeting (the "Meeting").

The Meeting is to be held Wednesday, December 17, 2025 at 10:00am (Pacific Time) at the office of Cozen O'Connor LLP, at Suite 2501 - 550 Burrard Street, Vancouver, B.C. On October 10, 2025, the Canadian Union of Postal Workers announced that the union was moving from a full, national strike to rotating strikes (the "Rotating Strikes"). While the Company will make all efforts to mail the Meeting Materials during the Rotating Strikes, shareholders are reminded that there can be no assurance that the Meeting Materials will be received by the shareholder prior to the Meeting.

The Company's Meeting Materials, comprising of the Notice of Annual General & Special Meeting of Shareholders, the Management Information Circular, the Form of Proxy, the Notice and Instruction (NI) Card are accessible on the Company's SEDAR+ profile at www.sedarplus.ca. and on the Company's website at https://www.siennaresources.com/investors/.

Shareholders of the Company are encouraged to access the meeting materials directly through the above-mentioned websites or contact the Company to request electronic copies of the meeting materials. Shareholders can contact the Company to request copies of the Meeting Materials by telephone at 604-646-6900 or 1-855-646-6901 (toll free in Canada and the United States) or by email at info@siennaresources.com.

As set out in the Meeting Materials, shareholders will be asked to consider and approve the following resolutions: (i) appointment of auditors until the next annual meeting and to authorize the directors to set the auditor's remuneration; (ii) set the number of directors until the next annual meeting; (iii) election of directors to hold office until the next annual meeting; and (iv) approval of the Company's omnibus equity incentive plan to replace the current omnibus incentive plan.

Detailed voting instructions are available on the Form of Proxy. The proxy cut-off is Monday, December 15, 2025, at 10:00 a.m. (Pacific Time). Registered shareholders can contact Computershare's Investor Centre at 1-800-564-6253 (8:30 a.m. to 8:30 p.m. EST; Monday to Friday) to request their proxies and voting control numbers. Beneficial shareholders who hold the Company's common shares in a brokerage account should contact their broker for details on how to submit their vote.

Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.

To view the source version of this press release, please visit https://www.newsfilecorp.com/release/273532