11:00 ET--It would be a mistake to dismiss the impact of the Trump administration's new 50% tariff on $20 billion of Canadian goods, says National Bank of Canada economists. For sure, 80% of Canadian goods will remain exempt from U.S. tariffs. Still, for firms directly affected, National Bank says the new tariff "could simply render their products uncompetitive in the U.S. market ... A prohibitive tariff concentrated in a handful of sectors can trigger a sharp drop in exports, lost market share, factory closures and weaker investment." The economists estimate the average tariff on manufacturers will jump to 10% from the current 6% level. National Bank adds it is paramount that Canadian policymakers tackle domestic factors that thwart growth as a way to soften the tariff blow.