PRESS RELEASE

Boulogne-Billancourt,
3rd April 2026
5:45 pm

Engineering and IT Services
Sensitivity: C1-Internal

Information pursuant to articles L. 233-8-II of French Commercial code and 223-16 of the AMF General Regulation in connection with the number of outstanding shares in the Company and related voting rights

Company: ALTEN SA (the “Company”)
Stock-exchange: Euronext Paris
Compartment: A
ISIN Code : FR0000071946

* Ordinary shares

Article 9 of ALTEN’s Articles of Association provides that any shareholder acting alone or in concert, in addition to the thresholds set forth in Article L. 233-7 of the French Commercial code, that crosses the threshold (upwards or downwards) of 3% of the share capital or voting rights must inform the Company of such crossing. This information must be notified by registered letter with acknowledgement of receipt within 15 days from the date on which such threshold was crossed.

About ALTEN

For more information: www.alten.com/investisseurs
Journalists’ details: alten@hopscotch.fr

As a European Leader in Engineering and Technology Consulting (ETC), ALTEN carries out design and research projects for Technical and IT divisions of major clients in industry, telecoms and services.

ALTEN’s stock is listed in compartment A of the Euronext Paris market (ISIN FR000001946); it is part of the SBF 120, the IT CAC 50 index and MIDCAP100, and is eligible for the deferred Settlement Service (SRD).

Engineering and IT Services
Sensitivity: C1-Internal