Luxembourg-based ArcelorMittal, an integrated metals and mining company, raised its 14.9% stake to 19.9% by paying A$20 a share for more than 10.6 million shares while South Korean steel company POSCO bought more than 20.2 million shares for a 10% stake also at a cost of A$20 a share. (US$1=A$1.03). ArcelorMittal bought the shares from…