U.S President Donald Trump says he’ll announce Monday the United States will impose 25 per cent tariffs on all steel and aluminum imports, including from Canada and Mexico. 9:30 a.m. EST: North American markets higher at the open Canada’s benchmark stock index, the S&P/TSX Composite, opened higher on Monday, up one per cent as of 9:30 a.m. EST. In New York, the S&P 500 Index also opened higher, up roughly half a percentage point.