Costain Group PLC (LSE:COST) launched a £10 million on-market share buyback but kept its dividend flat as the infrastructure construction group hailed the recovery of its balance sheet and confidence in long-term prospects. Revenue of £639.3 million was reported for the first half of 2024, down 4% from a year earlier due to a reduction from its transportation business, slightly offset by growth in its natural resources wing that serves the water, waste, hydrocarbons, chemicals and nuclear sectors.