OSB GROUP PLC

ISIN:GB00BLDRH360

29 June 2026

LEI number:213800ZBKL9BHSL2K459

OSB GROUP PLC (the “Company”)

Share Buyback Programme – Transactions in Own Shares

The Company announces that, for the period from 22 June 2026 to 26 June 2026, inclusive, it had purchased a total of 91,934 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.

22 June 2026London Stock ExchangeCBOE BXECBOE CXEAquis ExchangeNumber of ordinary shares purchased15,12015,3253,5431,603Highest price paid (per ordinary share)524.50p524.50p524.50p524.50pLowest price paid (per ordinary share)513.50p513.50p513.50p513.50pVolume weighted average price paid (per ordinary share)518.10p518.08p518.10p518.02p
23 June 2026London Stock ExchangeCBOE BXECBOE CXEAquis ExchangeNumber of ordinary shares purchased13,32814,9103,4391,444Highest price paid (per ordinary share)523.50p523.50p523.50p524.00pLowest price paid (per ordinary share)515.50p516.00p514.50p514.50pVolume weighted average price paid (per ordinary share)518.46p518.44p518.43p518.49p
24 June 2026London Stock ExchangeCBOE BXECBOE CXEAquis ExchangeNumber of ordinary shares purchased7,5748,3151,862757Highest price paid (per ordinary share)529.00p529.50p529.50p529.00pLowest price paid (per ordinary share)518.00p518.00p518.00p518.00pVolume weighted average price paid (per ordinary share)520.68p520.78p520.71p520.80p
25 June 2026London Stock ExchangeCBOE BXECBOE CXEAquis ExchangeNumber of ordinary shares purchased2202325014Highest price paid (per ordinary share)539.50p539.00p537.00p537.00pLowest price paid (per ordinary share)531.00p531.00p531.00p531.00pVolume weighted average price paid (per ordinary share)534.45p534.31p534.74p535.14p
26 June 2026London Stock ExchangeCBOE BXECBOE CXEAquis ExchangeNumber of ordinary shares purchased1,7091,999351139Highest price paid (per ordinary share)537.50p538.00p535.50p534.50pLowest price paid (per ordinary share)526.50p526.50p527.00p527.50pVolume weighted average price paid (per ordinary share)529.29p529.21p529.70p529.63p

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 341,605,791 ordinary shares.

No ordinary shares are held in treasury. Therefore, the total number of voting rights in the Company is 341,605,791.

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.

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

Issuer NameOSB GROUP PLCLEI223800ZBKL9BHSL2K459ISINGB00BLDRH360Intermediary NameJefferies International LimitedIntermediary CodeJEFFGB2XXXXTimezone GMTCurrencyGBP

Individual Transactions:

Please see attached PDF for full list of transactions.

Attachment