Reliance Infrastructure said that it had, on Monday, bought one lakh shares under its buy back programme. The company had said that it would buy back equity shares for an aggregate amount of up to Rs 1,000 crore. It has so far bought back 20.5 lakh equity shares amounting to Rs 129.42 crore. On Monday, the R Infra scrip closed 6.07 per cent lower at Rs 545.25 on the BSE.