Nippon Steel shares surged on Monday as US President Donald Trump approved its $14.9 billion bid for US Steel, marking a significant milestone in its 18-month pursuit and gaining entry to a crucial market for its growth plans. The approval marked the end of a turbulent process characterised by union opposition and two national security reviews. Nippon, the world's fourth-largest steelmaker, saw its shares rise three per cent to 2,915 yen by mid-day, outperforming the Nikkei 225 index. Trump signed an executive order on Friday allowing the merger to proceed, pending a national security agreement with the Treasury Department. The companies have since announced that they have signed the agreement, clearing the deal. Trump signed an executive order on Friday allowing the merger to proceed, pending a national security agreement with the Treasury Department. The companies have now signed the agreement, clearing the deal. "Investors have welcomed the resolution of uncertainty surrounding the deal," said Shinichiro Ozaki, senior analyst at Daiwa Securities. Attribution: Reuters Subediting: M. S. Salama