| 14/10/26 | COST | 09:27:40 | 14 Oct 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 12/10/26 | COST | 15:31:01 | 12 Oct 2026 | | COST | Director/PDMR Shareholding | Costain Group PLC | RNS |
| 09/10/26 | COST | 15:52:36 | 9 Oct 2026 | | COST | Update on AGM Political Donations Resolution Vote | Costain Group PLC | RNS |
| 07/10/26 | COST | 10:00:01 | 7 Oct 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 06/10/26 | COST | 15:20:16 | 6 Oct 2026 | | COST | Holding(s) in Company | Costain Group PLC | RNS |
| 02/10/26 | COST | 07:00:03 | 2 Oct 2026 | | COST | Costain selected for Pagabo Framework | Costain Group PLC | RNS |
| 01/10/26 | COST | 09:00:01 | 1 Oct 2026 | | COST | Director/PDMR Shareholding | Costain Group PLC | RNS |
| 01/10/26 | COST | 08:00:00 | 1 Oct 2026 | | COST | Total Voting Rights | Costain Group PLC | RNS |
| 30/09/26 | COST | 10:00:00 | 30 Sept 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 24/09/26 | COST | 11:30:01 | 24 Sept 2026 | | COST | Holding(s) in Company | Costain Group PLC | RNS |
| 24/09/26 | COST | 10:46:07 | 24 Sept 2026 | | COST | Scrip Dividend Reference Price | Costain Group PLC | RNS |
| 23/09/26 | COST | 12:14:25 | 23 Sept 2026 | | COST | Holding(s) in Company | Costain Group PLC | RNS |
| 23/09/26 | COST | 10:00:00 | 23 Sept 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 16/09/26 | COST | 10:00:00 | 16 Sept 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 15/09/26 | COST | 15:04:48 | 15 Sept 2026 | | COST | Holding(s) in Company | Costain Group PLC | RNS |
| 15/09/26 | COST | 08:20:28 | 15 Sept 2026 | | COST | Holding(s) in Company | Costain Group PLC | RNS |
| 09/09/26 | COST | 15:32:44 | 9 Sept 2026 | | COST | Holding(s) in Company | Costain Group PLC | RNS |
| 09/09/26 | COST | 11:02:07 | 9 Sept 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 02/09/26 | COST | 09:58:24 | 2 Sept 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 01/09/26 | COST | 10:00:00 | 1 Sept 2026 | | COST | Total Voting Rights | Costain Group PLC | RNS |
| 26/08/26 | COST | 10:00:01 | 26 Aug 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 20/08/26 | COST | 13:02:38 | 20 Aug 2026 | | COST | Holding(s) in Company | Costain Group PLC | RNS |
| 19/08/26 | COST | 11:55:52 | 19 Aug 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 13/08/26 | COST | 07:00:02 | 13 Aug 2026 | | COST | Half-year Financial Results | Costain Group PLC | RNS |
| 12/08/26 | COST | 10:00:01 | 12 Aug 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 05/08/26 | COST | 10:32:39 | 5 Aug 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 03/08/26 | COST | 10:00:00 | 3 Aug 2026 | | COST | Total Voting Rights | Costain Group PLC | RNS |
| 29/07/26 | COST | 10:30:00 | 29 Jul 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 27/07/26 | COST | 07:00:09 | 27 Jul 2026 | | COST | Investor Presentation via Investor Meet Company | Costain Group PLC | RNS |
| 22/07/26 | COST | 13:57:10 | 22 Jul 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 15/07/26 | COST | 10:30:01 | 15 Jul 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 15/07/26 | COST | 07:00:03 | 15 Jul 2026 | | COST | Costain extends contract with United Utilities | Costain Group PLC | RNS |
| 09/07/26 | COST | 11:15:13 | 9 Jul 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 01/07/26 | COST | 10:30:01 | 1 Jul 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 01/07/26 | COST | 09:30:13 | 1 Jul 2026 | | COST | Block Listing Interim Review | Costain Group PLC | RNS |
| 01/07/26 | COST | 09:25:10 | 1 Jul 2026 | | COST | Total Voting Rights | Costain Group PLC | RNS |
| 25/06/26 | COST | 10:25:14 | 25 Jun 2026 | | COST | Director/PDMR Shareholding | Costain Group PLC | RNS |
| 24/06/26 | COST | 10:30:00 | 24 Jun 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 23/06/26 | COST | 10:11:59 | 23 Jun 2026 | | COST | Director/PDMR Shareholding | Costain Group PLC | RNS |
| 18/06/26 | COST | 11:46:28 | 18 Jun 2026 | | COST | Director/PDMR Shareholding | Costain Group PLC | RNS |
| 18/06/26 | COST | 07:00:07 | 18 Jun 2026 | | COST | Costain wins West Winch Housing Road contract | Costain Group PLC | RNS |
| 17/06/26 | COST | 10:30:00 | 17 Jun 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 10/06/26 | COST | 09:27:04 | 10 Jun 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 09/06/26 | COST | 15:25:11 | 9 Jun 2026 | | COST | Holding(s) in Company | Costain Group PLC | RNS |
| 09/06/26 | COST | 07:00:03 | 9 Jun 2026 | | COST | Costain wins place on £700m TfL framework | Costain Group PLC | RNS |
| 03/06/26 | COST | 10:30:00 | 3 Jun 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 01/06/26 | COST | 10:31:24 | 1 Jun 2026 | | COST | Total Voting Rights | Costain Group PLC | RNS |
| 27/05/26 | COST | 09:34:23 | 27 May 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |
| 22/05/26 | COST | 13:00:00 | 22 May 2026 | | COST | Director/PDMR Shareholding | Costain Group PLC | RNS |
| 20/05/26 | COST | 09:55:24 | 20 May 2026 | | COST | Transaction in Own Shares | Costain Group PLC | RNS |