Canada faces another set of tariffs in its ongoing trade talks with the U.S. However, in this latest round of tariff announcements, investors have learned to largely tune them out as negotiating bluster rather than policy commitments.

It’s a possible sign that President Donald Trump’s wave of tariff letters is again raising concern among investors.

Wall Street's main indexes opened lower on Friday as President Donald Trump cranked up his tariff assault on Canada, deepening uncertainty around Washington's trade agenda. At 09:30 a.m., the Dow Jones Industrial Average fell 215.