The Aluminum Corporation of China (Chinalco) and the U.S. aluminum producer Alcoa bought a 12 percent stake in the Britain-listed company of iron ore giant Rio Tinto on Friday, the biggest ever stock trading case in value.

The total price of the acquisition stood at 14.05 billion U.S. dollars, the largest overseas investment ever made by a Chinese enterprise, Xinhua learned from Chinalco on Friday.

Sources from Chinalco told Xinhua that a large portion of the total investment came from the Chinese side, but they declined to elaborate.

Lu Youqing, deputy general manager of the country's top non-ferrous metals producer, said that the deal was a "significant strategic investment" by Chinalco and the company saw good prospects for the fast-growing mining industry and the value of Rio Tinto.

The partnership with Alcoa, the world's leading aluminum producer, demonstrated that Chinalco was accelerating its plans to go international, Lu said.

Alcoa Chairman and Chief Executive Officer Alain Belda said in a statement on the company's website that Rio Tinto "has a world-class portfolio of assets and is very well-positioned to prosper in the current mining cycle.

"This investment, made in partnership with Chinalco, allows us to mutually benefit from developments in the sector," said Belda. "We have known Chinalco for many years, dating back to our participation in the successful launch of Chalco's [initial public offering], and are looking forward to this new venture."

Chinalco said it made the joint acquisition through Shining Prospect Pte. Ltd. (SPPL), its wholly-funded subsidiary in Singapore.

Through its investment, Alcoa will acquire an equity stake in SPPL commensurate with its cash contribution to the investment, Alcoa said.

The China Development Bank was in charge of financial arrangements for Chinalco, while financial consulting was provided by Lehman Brothers and the China International Capital Corp. Ltd., according to Chinalco.

Chinalco has total assets of more than 200 billion yuan, with revenue exceeding 130 billion yuan last year.

The company said that it was investing more overseas and expanding its business from aluminum to other non-ferrous metals like copper.

Founded in 1873 and headquartered in Britain, Rio Tinto is the third-largest diversified mineral group. It became a leading aluminum producer last year by acquiring Alcan, a Canadian-based aluminum manufacturer.