The Canadian stock market opened sharply on Monday. Earlier, US President Donald Trump imposed 25% tariffs on most products from Canada and a 10% tariff on energy imports from Canada, prompting Canadian Prime Minister Justin Trudeau to promise retaliatory tariffs on US goods. The S&P/TSE Composite Index once fell 3.1%, the biggest intraday decline since August. Materials stocks were the only sector that rose in early Monday trading as gold stocks soared. Unless an agreement can be reached at the last minute, the US tariffs are scheduled to take effect on Tuesday. “The sell-off of the stock market after months of ignoring the imminent threat of a trade war should not be unusual for anyone,” said Colin Cieszynski, chief market strategist at SIA Wealth Management.