Transaction in Own Shares

OSB GROUP PLC
ISIN: GB00BLDRH360
08 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 01 June 2026 to 05 June 2026, inclusive, it had purchased a total of 1,017,466 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.

01 June 2026	London Stock Exchange	CBOE BXE	CBOE CXE	Aquis Exchange
Number of ordinary shares purchased	73,435	83,404	23,765	10,546
Highest price paid (per ordinary share)	518.50p	518.50p	518.50p	518.00p
Lowest price paid (per ordinary share)	505.00p	505.00p	505.00p	505.00p
Volume weighted average price paid (per ordinary share)	510.87p	510.84p	510.85p	510.87p

02 June 2026	London Stock Exchange	CBOE BXE	CBOE CXE	Aquis Exchange
Number of ordinary shares purchased	74,077	84,911	23,898	10,674
Highest price paid (per ordinary share)	509.50p	509.50p	509.00p	509.00p
Lowest price paid (per ordinary share)	496.60p	497.00p	499.40p	498.40p
Volume weighted average price paid (per ordinary share)	505.97p	505.95p	505.94p	505.95p

03 June 2026	London Stock Exchange	CBOE BXE	CBOE CXE	Aquis Exchange
Number of ordinary shares purchased	84,140	97,027	27,084	11,901
Highest price paid (per ordinary share)	511.50p	511.00p	511.00p	510.50p
Lowest price paid (per ordinary share)	501.00p	501.00p	501.00p	500.50p
Volume weighted average price paid (per ordinary share)	505.34p	505.31p	505.32p	505.34p

04 June 2026	London Stock Exchange	CBOE BXE	CBOE CXE	Aquis Exchange
Number of ordinary shares purchased	79,394	87,618	25,296	11,258
Highest price paid (per ordinary share)	507.50p	507.50p	507.50p	507.00p
Lowest price paid (per ordinary share)	500.00p	500.00p	500.00p	500.00p
Volume weighted average price paid (per ordinary share)	503.36p	503.33p	503.30p	503.42p

05 June 2026	London Stock Exchange	CBOE BXE	CBOE CXE	Aquis Exchange
Number of ordinary shares purchased	81,012	91,687	25,591	10,748
Highest price paid (per ordinary share)	511.00p	511.00p	511.00p	511.00p
Lowest price paid (per ordinary share)	500.50p	500.50p	500.50p	500.50p
Volume weighted average price paid (per ordinary share)	505.34p	505.34p	505.33p	505.34p

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 342,826,551 ordinary shares.

No ordinary shares are held in treasury. Therefore, the total number of voting rights in the Company is 342,826,551.

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

• 2026.06.05_OSBG Buyback Fills