Rio Tinto PLC (LSE:RIO) has entered into a definitive arrangement agreement to acquire full ownership of Turquoise Hill, and the giant Oyu Tolgoi copper project that it owns in Mongolia. The Turquoise Hill board of directors has unanimously recommended minority shareholders vote in favour of Rio Tinto's offer of C$43.00 per share in cash. This represents a premium of 67% to Turquoise Hill's closing price of C$25.68 per share on 11 March 2022, the day prior to Rio Tinto's initial public proposal to acquire Turquoise Hill. Rio Tinto has agreed to provide Turquoise Hill with secured short-term liquidity during the transaction period of up to US$1.1bn, which would need to be repaid from an equity raising from shareholders in the first half of 2023 if the transaction is not approved by shareholders. The deal follows years of wrangling over the funding of construction at Oyu Tolgoi, which is one of the world's largest copper developments.