Glencore and Rio Tinto held early-stage merger talks last year, but the discussions are no longer active, a source familiar with the matter told Reuters, as global miners rush to boost their exposure to copper.

Rio Tinto Group shares fell as much as 1.8% in Sydney after Bloomberg News earlier reported the world’s second-biggest miner held early-stage talks with Glencore Plc about a deal.Most Read from BloombergThese Homes Withstood the LA Fires.

Rio Tinto is the world’s second-biggest miner, with a market value of about US$103 billion ($140.8 billion) at the close of trading in London on Jan 16, while Glencore was valued at about US$55 billion. BHP is worth about US$126 billion.

Rio Tinto, and Glencore have held early-stage talks about combining their businesses, Bloomberg News reported on Thursday, citing people familiar with the matter. The potential merger between the two mining heavyweights,

Rio Tinto Group and Glencore Plc have been discussing combining their businesses, according to people familiar with the matter, in what could result in the mining industry’s largest-ever deal.Most Read from BloombergThese Homes Withstood the LA Fires.

Rio Tinto and Glencore are considering a merger that could create the largest iron ore mining company globally, valued at around $158 billion. Previously in 2014, Rio Tinto rejected a similar offer from Glencore.

Rio Tinto reports its lowest annual iron ore shipments in two years, partly as heavy rains in Western Australia impacted output in the December quarter, but says the global economy is showing signs of strength.

Rio Tinto is the world’s second most valuable mining company and shares with its Melbourne-based neighbour BHP the distinction of being valued at more than $100 billion, but only just.

Group and Glencore Plc (OTC:GLNCY) are reportedly in early-stage discussions about a potential combination, Bloomberg reported on Thursday, citing sources close to the matter.