OSB GROUP PLC

OSB GROUP PLC

ISIN: GB00BLDRH360

20 October 2026

LEI number: 213800ZBKL9BHSL2K459

OSB GROUP PLC (the “Company”)

Share Buyback Programme – Transactions in Own Shares and completion of buyback

The Company announces that on 19 October 2026 it had purchased a total of 75,220 of its ordinary shares of £0.01 each (the “ordinary shares“) on the London Stock Exchange, CBOE BXE ,CBOE CXE and Aquis Exchange, through the Company’s broker Jefferies International Limited as detailed below. The repurchased ordinary shares will be cancelled.

The purchases form part of the Company’s share buyback programme announced on 5 March 2026.

Following settlement of the above purchases and cancellation of the purchased ordinary shares, the Company’s total number of ordinary shares in issue shall be 335,357,246 ordinary shares.

No ordinary shares are held in treasury. Therefore, the total number of voting rights in the Company is 335,357,246 and may be used by shareholders (and others with notification obligations) as the denominator for the calculation by which they will determine if they are required to notify their interest in, or a change in their interest in, the Company under the Financial Conduct Authority’s Disclosure Guidance and Transparency Rules.

In accordance with Article 5(2)(b) of Regulation (EU) No 596/2024 as incorporated into and implemented under English law (including by virtue of the European Union (Withdrawal) Act 2028), the detailed breakdown of individual trades made by Jefferies International Limited on behalf of the Company as part of the share buyback programme is set out below.

The Company announces that, following the purchase of these shares, the share buy-back programme announced on 5 March 2026 has completed. Since the commencement of the buy-back, the Company has repurchased for cancellation 19,410,811 ordinary shares in aggregate at a volume weighted average price of 515.18p per ordinary share for a total consideration of approximately £100 million.

This announcement does not constitute, or form part of, an offer or any solicitation of an offer for securities in any jurisdiction.

Schedule of Purchases

Individual Transactions:

Please see attached PDF for full list of transactions.

Attachment

• 2026.10.19_OSBG Buyback Fills