London CNN  —  Mining giant BHP has made a near-$40 billion bid to take over its UK rival Anglo American in what would be the largest mining deal on record. BHP said in a statement Thursday that it valued Anglo American shares at £25.08 ($31.40) apiece, or £31.1 billion ($38.9 billion) in total. If completed, the acquisition would increase BHP’s access to copper reserves, it added. The potential deal would have a higher value than the $38.3 billion acquisition of Switzerland’s Xstrata by commodities company Glencore in 2012, according to Dealogic data. It would also be the biggest merger or acquisition in the mining industry by value since Dealogic began collecting the data in 2004. Anglo American’s board is “currently reviewing this proposal,” the company said in a statement, adding that there was “no certainty” a formal offer would be made by BHP, or the terms of that potential offer. BHP has until May 22 to make a formal offer. Shares in Anglo American soared as much as 13.8% on the news. By 5.47 a.m. ET, they were trading at £24.55 ($30.72). Shares in BHP closed 0.6% down in Australia. Copper is an essential component in some renewable energy technologies, including solar panels and electric vehicles. And it is in high demand: The price of the metal on the London Metals Exchange has risen more than 13% so far this year to almost $10,000 a metric ton, its highest level in about two years. A year ago, BHP acquired Australian rival Oz Minerals to widen its access to copper and nickel. The buyout was part of BHP’s strategy to “meet increasing demand for the critical minerals needed for electric vehicles, wind turbines and solar panels,” company CEO Mike Henry said in a statement at the time. The approach by BHP may also fuel concerns about some of the United Kingdom’s biggest companies leaving the London Stock Exchange. The buyout offer “will send a fresh chill through the City of London,” Susannah Streeter, head of money and markets at Hargreaves Lansdown, wrote in a note Thursday. “There are concerns that, if the deal goes through, it could be the tip of the iceberg and more giants could leave the exchange.”