Traders reacted swiftly to US President Donald Trump’s declaration that he would push through with new tariffs on Mexico and Canada and an extra levy on China, dumping stocks and commodities amid concern about the impact on global growth. The selling was heaviest on Wall Street, with the S & P 500 tumbling almost 2 per cent and the technology-heavy Nasdaq dropping 2.2 per cent as the president dashed hopes that a last-minute deal could be reached. He also signed an order that doubles tariffs on China to 20 per cent. Loading…