Transaction in Own Shares

OSB GROUP PLC
ISIN: GB00BLDRH360
1 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 26 May 2026 to 29 May 2026, inclusive, it had purchased a total of 705,468 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.

26 May 2026	London Stock Exchange	CBOE BXE	CBOE CXE	Aquis Exchange
Number of ordinary shares purchased	89,134	96,279	28,078	12,970
Highest price paid (per ordinary share)	512.00p	512.50p	512.50p	512.00p
Lowest price paid (per ordinary share)	506.00p	506.50p	507.50p	508.50p
Volume weighted average price paid (per ordinary share)	510.94p	510.87p	510.91p	510.82p

27 May 2026	London Stock Exchange	CBOE BXE	CBOE CXE	Aquis Exchange
Number of ordinary shares purchased	75,774	80,315	23,968	11,215
Highest price paid (per ordinary share)	521.00p	521.00p	521.00p	521.00p
Lowest price paid (per ordinary share)	512.50p	514.50p	515.00p	516.00p
Volume weighted average price paid (per ordinary share)	517.87p	517.95p	517.90p	518.02p

28 May 2026	London Stock Exchange	CBOE BXE	CBOE CXE	Aquis Exchange
Number of ordinary shares purchased	70,938	75,327	22,455	10,514
Highest price paid (per ordinary share)	516.00p	516.00p	515.50p	515.00p
Lowest price paid (per ordinary share)	508.00p	507.00p	507.50p	507.00p
Volume weighted average price paid (per ordinary share)	510.79p	510.81p	510.81p	510.75p

29 May 2026	London Stock Exchange	CBOE BXE	CBOE CXE	Aquis Exchange
Number of ordinary shares purchased	41,738	46,902	13,661	6,200
Highest price paid (per ordinary share)	519.50p	519.50p	519.50p	519.50p
Lowest price paid (per ordinary share)	514.50p	514.50p	514.50p	514.00p
Volume weighted average price paid (per ordinary share)	517.61p	517.58p	517.56p	517.58p

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 343,843,598 ordinary shares.

No ordinary shares are held in treasury. Therefore, the total number of voting rights in the Company is 343,843,598.

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 Name	OSB GROUP PLC
LEI	223800ZBKL9BHSL2K459
ISIN	GB00BLDRH360
Intermediary Name	Jefferies International Limited
Intermediary Code	JEFFGB2XXXX
Timezone	GMT
Currency	GBP

Individual Transactions:

Please see attached PDF for full list of transactions.

Attachment

• 2026.05.29_OSBG Buyback Fills