Groupe Bruxelles Lambert SA

Transaction in Own Shares • Dec 15, 2025

Delivering meaningful growth

Transactions on GBL Shares

Disclosure of transaction on GBL shares from December 8, 2025, until December 12, 2025 (included) Implementation of the authorization of the Extraordinary General Shareholders' Meeting of May 2, 2025

Purchases

GBL, directly and through its subsidiaries, acquired during the period from December 8, 2025 until December 12, 2025 included, as part of:

• The share buyback program: 0 GBL share
• The share buyback program by an independent financial institution on the basis of a discretionary mandate (until March 13, 2026) in the central order book of a regulated market or MTF: 99,651 GBL shares

Trade date	Number of shares	Average price (EUR)	Lowest price (EUR)	Highest price (EUR)	Amount (EUR)	Market (MIC Code)
12/08/2025	1,200	74.33	74.15	74.50	89,200	AQEU
12/08/2025	2,876	74.35	74.10	74.50	213,833	CEUX
12/08/2025	1,300	74.32	74.15	74.50	96,618	TQEX
12/08/2025	11,408	73.89	73.80	74.50	842,888	XBRU
12/09/2025	1,071	73.89	73.55	74.20	79,134	AQEU
12/09/2025	5,001	73.84	73.55	74.20	369,267	CEUX
12/09/2025	1,128	73.87	73.55	74.20	83,324	TQEX
12/09/2025	12,719	73.63	73.55	74.20	936,538	XBRU
12/10/2025	1,100	73.14	73.00	73.35	80,450	AQEU
12/10/2025	7,255	73.16	73.00	73.35	530,740	CEUX
12/10/2025	1,123	73.13	72.95	73.35	82,128	TQEX
12/10/2025	18,164	73.15	72.95	73.50	1,328,787	XBRU
12/11/2025	1,000	73.39	73.05	73.75	73,394	AQEU
12/11/2025	3,736	73.46	73.05	73.70	274,428	CEUX
12/11/2025	930	73.34	73.05	73.65	68,205	TQEX
12/11/2025	10,022	73.45	73.05	73.65	736,116	XBRU
12/12/2025	1,548	74.04	73.80	74.30	114,619	AQEU
12/12/2025	6,070	74.12	73.80	74.25	449,905	CEUX
12/12/2025	1,100	74.08	73.80	74.30	81,485	TQEX
12/12/2025	10,900	73.79	73.55	74.30	804,260	XBRU
Total	99,651	73.61			7,335,319

• The liquidity agreement: 0 GBL share

Sales

GBL, directly and through its subsidiaries, sold during the period from December 8, 2025 until December 12, 2025 included, as part of:

• The liquidity agreement: 0 GBL share

As of December 12, 2025, GBL holds directly and through its subsidiaries 12,211,786 GBL shares representing 9.2% of the issued capital and holds no shares under the liquidity agreement. On that date, 23.2% of the eighth share buyback program is executed1.

Following GBL's decision to use the safe harbour2 regime for the on-the-market share buybacks in the context of a EUR 598.9 million envelope, the liquidity contract with an independent financial institution has been suspended for an indefinite period.

For more information, please contact:

Tel: +32 2 289 17 72 Tel: +32 2 289 17 64

Xavier Likin Alison Donohoe

Chief Financial Officer Head of Investor Relations xlikin@gbl.com adonohoe@gbl.com

About Groupe Bruxelles Lambert

Groupe Bruxelles Lambert ("GBL") is an established investment holding company, with seventy years of stock exchange listing and a net asset value of €14.0bn at the end of September 2025. As a leading and active investor in Europe, GBL focuses on long-term value creation with the support of a stable family shareholder base.

GBL is focused on delivering meaningful growth by providing attractive returns to its shareholders through a combination of growth in its net asset value per share, a sustainable dividend and share buybacks.

GBL is listed on Euronext Brussels (Ticker: GBLB BB; ISIN code: BE0003797140) and is included in the BEL20 index.

¹ cf. http://www.gbl.com/en/transactions-gbl-shares

² Provided for in Regulation (EU) No. 596/2014 of 16 April 2014 on market abuse and Delegated Regulation (EU) No. 2016/1052 of 8 March 2016 with regard to regulatory technical standards for the terms of buyback programs and stabilization measures