Bloomberg reported that Rio Tinto Group's shares in Sydney traded at their biggest discount to BHP Billiton Limited's hostile USD 115 billion takeover bid, signaling concern amongst investors the world's largest mining acquisition may fail.

Rio's shares traded 16% below BHP's all stock offer, the largest gap since the initial approach in November. The London traded stock traded at a 20.09% discount, close to the record margin of 20.13%.

It may be noted that Mr Tom Albanese CEO of Rio rejected BHP's sweetened offer of 3.4 shares for each Rio share on February 6th 2008, saying the bid undervalues its assets and prospects.

Mr Tom Albanese CEO of BHP this month said that falling commodity prices and a slowing global economy will help convince investors to support the bid. He added that shareholders are likely to favor the takeover because BHP has higher profit margins and lower debt than Rio.