Key Terms and Conditions of the Share Buy-Back

GAZTRANSPORT ET TECHNIGAZ
Société anonyme with a share capital of €371,177.72
Registered office: 1 route de Versailles – 78470 Saint-Rémy-lès-Chevreuse, France
662 001 403 R.C.S. Versailles

Main terms and conditions of the share buy-back programme in accordance with the conditions and obligations set by Articles 241-1 and seq. of the General Regulations of the Autorité des marchés financiers (AMF)

Implementation of the share buy-back programme authorised by the Combined Shareholders’ meeting on June 16, 2026

Issuer: GTT / ISIN code: FR 0011726835 (compartment A)

Stock concerned: Ordinary shares

Implementation authorized by: Combined Shareholders’ meeting on June 16, 2026

Implementation decision date: June 16, 2026

Maximum proportion of the share capital that may be acquired pursuant to the Shareholders’ authorization: 10% of the number of ordinary shares composing GTT’s share capital, or, for indicative purposes 3,711,777 shares on the basis of the capital as at December 31, 2025.

It is specified that:

(i) the number of shares acquired for retention and their subsequent delivery as part of an acquisition transaction cannot exceed 5% of its share capital;

(ii) when the shares are bought back to improve liquidity under the conditions defined by the general regulations of the Autorité des Marchés Financiers (AMF), the number of shares used for calculating the above-specified 10% limit corresponds to the number of shares bought, less the number of shares sold, during the period of the authorisation;

(iii) the Company may not directly or indirectly own more than 10% of its capital.

Maximum purchase price: €260 per share (fees not included).

Maximum amount of purchases authorized by the programme: €965,062,020.

Objectives of the programme:

• the implementation of (i) share purchase option plans or (ii) free share award plans, or (iii) the allocation or sale of shares to employees or corporate officers of the Company or of Group companies under the conditions and in accordance with the procedures allowed by law, notably with respect to Company profit-sharing; or the implementation of any employee savings scheme under the conditions provided for by law, specifically Articles L. 3332-1 et seq. of the French Labour Code, the sale of shares previously acquired by the Company pursuant to the 15th resolution of the Combined Shareholders’ meeting of June 16, 2026 or providing for the free allocation of these shares in the form of a top-up of Company securities and/or to replace the discount, or (iv) any other form of award, allocation or transfer to employees and/or corporate officers of the Company or affiliated companies;

• the delivery of shares upon the exercise of rights attached to securities giving right to repayment, conversion, exchange, presentation of a warrant, or any other means of allocating shares of the Company;

• the retaining and later delivery of shares (in exchange, payment or other) as part of an acquisition transaction, limited to 5% of the number of shares comprising the share capital;

• the cancellation of all or part of the shares bought back under a resolution of a Shareholders’ Meeting in force; and

• the stimulation of the secondary market or the liquidity of the shares by an investment services provider acting under a liquidity contract in compliance with the market practice recognised by the Autorité des Marchés Financiers.

This share buyback program would also be intended to allow the Company to operate for any other permitted purpose or which would become permitted by any applicable laws or regulations in force and to implement any practice that would be allowed by the Autorité des Marchés Financiers. In such event, the Company would inform its shareholders through a press release.

The acquisition or transfer of shares may be carried out at any time, within the limits set by legal and regulatory provisions and those provided for in the 15th resolution of the Combined Shareholders’ meeting of June 16, 2026, on one or more occasions, by any means authorised by the legal and regulatory provisions in force, on regulated markets, multilateral trading facilities, systematic internalisers or over-the-counter, including by acquisition or sale of blocks of shares (without limiting the portion of the buyback program that may be carried out by this means), by tender offer or exchange offer, or by use of options or other forward financial instruments or by delivery of shares following the issue of securities giving access to the Company’s capital by conversion, exchange, redemption, exercise of a warrant or in any other manner, either directly or indirectly through an investment services provider.

The Board of Directors may use this authorisation at