Severstal, Posco, ArcelorMittal and Metinvest have begun due diligence on Ukraine’s Zaporizhstal (UX: ZPST UK), according to local media reports. South Korea’s Posco confirmed yesterday that it placed a preliminary bid for a controlling stake in Zaporizhstal. Severstal, ArcelorMittal and Metinvest have yet to comment on the rumors. Acquisitions proposals will reportedly be considered in June. Zaporizhstal shares rose 18.18% yesterday on the UX.