AMBOISE : SIMPLIFIED CASH TENDER OFFER FOR THE ORDINARY SHARES IN ALTAMIR INITIATED BY AMBOISE SAS_PRESS RELEASE OF SEPTEMBER 12, 2025 RELATED TO THE AVAILIBILITY OF THE OFFER DOCUMENT

OFFER PRICE:

28.50 euros per Altamir share1

1 It is reminded that Altamir's General Meeting approved on April 23, 2025, the payment of a dividend of €1.06 per share in respect of the 2024 financial year, which will be paid no later than September 30, 2025, with the ex-dividend date set on September 26, 2025. As the Offer acceptance period ends on September 26, any shareholder tendering their shares after September 25, 2025, will receive the dividend and, consequently, the Offer Price ex-dividend, i.e. €27.44 per share, if they tender their shares to the Offer.

OFFER PERIOD:

10 trading days

The schedule of the simplified cash tender offer referred to herein (the “Offer”) will be determined by French Autorité des marchés financiers (the « AMF ») in accordance with its general regulation (the “AMF General Regulation”).

This press release has been prepared by Amboise SAS (“Amboise”) and published in accordance with Article 231-27 2° of the general regulations of the AMF.

Pursuant to the provisions of Article L. 621-8 of the French Monetary and Financial Code and of Article 231-23 of its General Regulation, the AMF, in accordance with its statement of compliance, granted visa n°25-368 dated 11 September 2025 on the offer document regarding the simplified cash tender offer initiated by Amboise SAS for the ordinary shares of Altamir (the "Offer Document").

The Offer Document is available on the website of the AMF (www.amf-france.org) and Altamir (www.altamir.fr) and may be obtained free of charge from: Amboise SAS – 61, rue des Belles Feuilles – 75116 Paris, de BNP Paribas – 16 boulevard des Italiens – 75009 Paris et de Crédit Agricole Corporate and Investment Bank - 12, place des Etats-Unis – CS 70052 – 92547 Montrouge cedex.

This press release is for informational purposes only. It does not constitute an offer to the public and shall not be distributed outside of France. The distribution of this press release, the Offer and its acceptance may be subject to specific regulations or restrictions in certain countries. The Offer is not directed to any persons subject to such restrictions, neither directly nor indirectly, and may not be accepted in any way from a country where the Offer would be subject to such restrictions. Therefore, persons in possession of this press release are responsible for finding all relevant information regarding potential applicable local restrictions and for complying with such restrictions. Amboise SAS shall not be held liable for any violation of such restrictions by any person.

The Offer Document must be read together with all other documents published in connection with the Offer. In accordance with Article 231-28 of the AMF's General Regulation, a description of the legal, financial and accounting characteristics of the Bidder will be made available to the public no later than the day before the opening of the Offer. A press release will be issued to inform the public of the arrangements for making this document available.

Prior to the opening of the Offer, the AMF and Euronext will respectively publish a notice of opening and schedule, and a notice announcing the terms and schedule of the Offer.

Not to be published, released or distributed, directly or indirectly, in the United States of America or in any other country where the distribution or circulation of such a press release is prohibited by law

For further information, please contact: