Rio Tinto is buying another $2.5 billion of its own shares

Amid general weakness for mining stocks on Thursday, Rio Tinto managed to eke out modest gains in New York trading. Investors poured money into the world's second largest miner on news that the Melbourne-based giant plans to buy back an additional $2.5 billion worth of its own shares. This brings the total amount this year up to $4 billion. Previous announcements for buy backs were made in February and August.

Rio Tinto is embarking on the share buy back after theĀ $2.69 billion sale of a number of coal interests that it approved to China-backed Yancoal in June. Some shareholders at that time had called for the money to be used for buy back shares or to increase dividends.