Stock markets on both sides of the border took a steep tumble Monday as the reality of a U.S.-Canada trade war took further hold, with the TSX losing almost 400 points, while the blue-chip Dow was down almost 900 points and the Nasdaq was four per cent lower.

The S&P/TSX composite index was down 378.05 points at 24,380.71 shortly after markets closed.

In New York, the Dow Jones industrial average was down 890.01 points at 41,911.71, or more than two per cent. The S&P 500 index was down 155.61 points or 2.7 per cent at 5,614.59, and tech stocks performed worst of all, with the Nasdaq composite down by 727.90 points or four per cent at 17,468.32.