ST. LOUIS ( TheStreet) -- Peabody Energy ( BTU) and ArcelorMittal ( MT) said Monday they are launching a hostile A$4.7 billion ($5.2 billion) takeover bid for Australia's Macarthur Coal . Earlier Monday, the board of Macarthur Coal, the world's largest producer of pulverized coal product that is used to make steel, rejected the bid, calling it "opportunistic." The offer, for A$15.50 a share, "appears to be an opportunistic attempt to acquire Macarthur at a time of global economic volatility and regulatory uncertainty in Australia and fails to reflect Macarthur's industry leading position and the growth potential of its unique assets," said Macarthur Chairman Keith DeLacy, in a statement. Macarthur said it told Peabody, the U.S. coal mining company, and steelmaker ArcelorMittal that it would recommend a AU$16 a share offer, based on certain conditions such as Macarthur not holding talks with rival suitors. But the parties couldn't agree on a deal. "Peabody and ArcelorMittal believe our bid is compelling," said Peabody Chairman and CEO Gregory Boyce, "And we have decided to take this attractive offer directly to Macarthur shareholders to provide them with significant value." ArcelorMittal, which already holds a 16% stake in Macarthur, and Peabody made their joint takeover bid for Macarthur around mid-July. -- Written by Joseph Woelfel >To contact the writer of this article, click here: Joseph Woelfel >To submit a news tip, send an email to: email@example.com.