New Delhi: State-owned Nalco Friday said its board has approved proposal to buyback shares worth Rs 504.8 crore.National Aluminium Company Ltd in a filing to the BSE said that "the board of directors of the company in their meeting held on October 12, 2018 has unanimously approved.the proposal to buyback not exceeding 6,73,11386 equity sharesin cash for an aggregate consideration not exceeding Rs 504,83,53,950."Aluminium maker Nalco had earlier reported a five-fold jump in net profit at Rs 687 crore for the first quarter ended June 30, 2018.