COST Costain Group Plc

21 October 2024

Costain Group PLC

Transaction in own shares

Costain Group PLC ("Costain") announces that, in accordance with the terms of its share buyback programme (the "Buyback Programme") announced on 21 August 2024, it has purchased the following number of its ordinary shares of 1 pence each ("Ordinary Shares") on the London Stock Exchange through Investec.

The purchased Ordinary Shares will be cancelled. The Company does not hold any Ordinary Shares in treasury.

Costain has now purchased 7,450,935 Ordinary Shares in aggregate for cancellation under the Buyback Programme.  Following settlement of the above purchases and cancellation of the purchased Ordinary Shares, the Group's total number of Ordinary Shares in issue will be 271,034,102 Ordinary Shares (including the 19,008 scrip dividend Ordinary Shares issued on 18 October 2024 as announced on 16 October 2024).

Details of Trades:

   Aggregate information

Individual Transactions

In accordance with Article 5(1)(b) of Regulation (EU) No 596/2014 as it applies in the UK (the Market Abuse Regulation), the table below contains detailed information of the individual trades made by Investec on behalf of Costain as part of the Buyback Programme.

Enquiries:

Issuer name: Costain Group PLC

LEI: 213800PKIJBZ2EDTKC88

ISIN: GB00B64NSP76

Classification: 2.4. Acquisition or disposal of the issuer's own shares

Intermediary name: Investec

Intermediary Code: MIDLGB22XXX

Timezone: BST

Currency: GBp