Metsä Board Corporation Stock Exchange Managers' transactions 28 August 2025 at 1:05 pm EEST In accordance with the resolution of the Annual General Meeting of Metsä Board Corporation (the “Company”) held on 20 March 2025, approximately one half of the annual remuneration of the Board of Directors is paid in the Company's B-series shares acquired through public trading. The payment of the remuneration does not affect the number of treasury shares held by the Company. Pursuant to this resolution, and to supplement the remuneration previously paid on 2 May 2025, the following shares have been acquired for and on behalf of Jussi Vanhanen, who commenced as Chairman of the Board of Directors on 1 July 2025, proportionate to the approximately 8.5-month term of chairmanship: Metsä Board Corporation - Managers' transactions - Vanhanen ____________________________________________ Person subject to the notification requirement Name: Vanhanen, Jussi Position: Member of the Board/Deputy member Issuer: Metsä Board Corporation LEI: 743700KKB8Q035K38488 Notification type: INITIAL NOTIFICATION Reference number: 743700KKB8Q035K38488_20250829084345_94 ____________________________________________ Transaction date: 2025-08-28 Venue: XHEL Instrument type: SHARE ISIN: FI0009000665 Nature of the transaction: RECEIPT OF A SHARE-BASED INCENTIVE Transaction details (1): Volume: 3529 Unit price: 0.00 EUR Aggregated transactions (1): Volume: 3529 Volume weighted average price: 0.00 EUR METSÄ BOARD CORPORATION Further information: Katri Sundström, VP, Investor Relations, tel. +358 10 462 0101 Eeva Impiö-Loimaala, General Counsel, tel. +358 44 040 3877 Metsä Board metsagroup.com/metsaboard (http://www.metsagroup.com/metsaboard/) Metsä Board is a producer of lightweight and high-quality folding boxboards, food service boards and white kraftliners. The fresh wood fibres we use in our products are a renewable and recyclable resource, that can be traced back to Northern European forests. We aim to have completely fossil-free mills and raw materials by 2030. We promote a culture of diversity, equality and inclusion. Metsä Board is listed on the Nasdaq Helsinki. In 2024 our sales totalled EUR 1.9 billion, and we have around 2,300 employees. Metsä Board is part of Metsä Group, whose parent company Metsäliitto Cooperative is owned by over 90,000 Finnish forest owners. Follow Metsä Board: LinkedIn (https://www.linkedin.com/company/metsa -board/) Instagram (https://www.instagram.com/metsaboard/?hl=en) YouTube (https://www.youtube.com/playlist?list=PLF6CD152EF0DA1E61)