Rio Tinto’s $15.2bn rights offer, the fifth-biggest on record, on Thursday generated strong demand from UK investors who snapped up almost 97% of the 524m new shares offered in London at £14 per share – raising about £7.1bn, more than a fifth of its market cap. Rio was also selling 150m new shares in Australia at $A28.29 per share. China’s state-controlled Chinalco confirmed it had taken up its full entitlement to Rio’s issue to maintain its 9% stake in the miner, despite the recent failure of their investment deal.