Corporate Update

Vancouver, British Columbia--(Newsfile Corp. - May 29, 2026) - Sienna Resources Inc. (TSXV: SIEN) (OTCID: SNNAF) (WKN: A418KR) (the "Company" or "Sienna") wishes to announce that it has elected to rely on Coordinated Blanket Order 51-933 Exemptions to Permit Semi-Annual Reporting for Certain Venture Issuers (the " Blanket Order ") and move to semi-annual financial reporting. Jason Gigliotti, President of Sienna Resources Inc., stated, "Moving to semiannual reporting aligns with our corporate mandate to maximize cost savings without diminishing the quality of our work. Also in line with this is the hiring of a European-focused marketing group.

This comes at a time when management expects to be active on multiple work programs commencing next month. These are exciting times for Sienna as we enter our most active period in years." The Blanket Order permits eligible venture issuers to voluntarily move from quarterly to semi-annual financial reporting. The Company has determined that it meets the eligibility criteria under the Blanket Order, including that it is a venture issuer listing on TSX Venture Exchange, has annual revenue of less than $10 million, and has a clean 12-month continuous disclosure record.

Under the Blanket Order, the Company will be exempt from filing interim financial reports and related management's discussion & analysis (" MD&A ") for its first and third quarters. The Company's fiscal year ends on December 31. The initial period for which the Company will not file an interim financial report and related MD&A in reliance of the Quarterly Reporting Exemption will be for the three-month period ended March 31, 2026.

The Company will continue to file its audited annual financial report and related MD&A (due within 120 days of December 31) and six-month interim financial report and related MD&A (due within 60 days of June 30). This news release is being filed pursuant to the Blanket Order. Sienna also wishes to announce it has engaged Dr. Reuter Resources GmbH ("Dr.

Reuter") to provide investor relations services to Sienna (the "IR Agreement"). The IR Agreement, which was executed on May 26, 2026 (the "Execution Date"), has a term of six months effective on the Execution Date, and has a three-month review period whereby this IR Agreement can be terminated by either party within 14 days of this date with no penalty. Dr. Reuter provides modular services, including roadshows, digital IR, institutional investor outreach, financial media relations, capital markets conference support, and assistance with disclosure obligations, across major markets in the U.S. and Europe.

Under the terms of the IR Agreement, Dr. Reuter will provide services, as appropriate, that include campaign and editorial articles, translation and distribution of press releases, journalist outreach, and social media campaigns. Sienna will verify the contents/materials prior to the distribution. In consideration for the services, Sienna will pay Dr. Reuter €5,500 per month.

Dr. Reuter is not related to the Company and, to the Company's knowledge, has no interest, directly or indirectly, in the Company or its securities. Dr. Reuter's business is located at Friedrich Ebert Anlage 35-37, Tower 185, 60327, Frankfurt, Germany. Its email contact is e.reuter@dr-reuter.eu and its phone number is +49 69 1532 5857.

Contact Information Tel: 604-646-6900 www.siennaresourcesinc.com "Jason Gigliotti" President Sienna Resources Inc. 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/299316 TMX Newsfile May 29, 2026 - 12:01 AM PDT News by QuoteMedia www.quotemedia.com