Shares in Rio Tinto have slumped as much as 23 per cent in trade today, as the miner launches its $US15.2 billion ($A19 billion) rights issue though market observers viewed the closing value as a positive result when the rights were taken into account.
Rio's share price plummeted from yesterday's close of $73.23 to a low of $56.70 before closing at $57.68 today.
However the share price fall was only marginal, 7.65 cents, as a result of the adjustment following the launch of the rights issue.
The mining giant today opened its rights issue where shareholders in the locally listed Rio can buy 21 new shares for every 40 held, at a price of $28.29 a share, and trade the rights.
The rights closed at $29.74 today. The rights issue is due to close on July 1.
In documents released yesterday, Rio said the rights issue price represented a discount of around 47.2 per cent to the theoretical ex-rights prices of $53.61 a share.
Rio has previously said it will use funds from the raising to reduce its mountain of debt, acquired from the purchase of Alcan in 2007.
