Major stock indexes were slightly lower on Friday as U.S. President Donald Trump's announcement of tariffs on imports from Canada fanned worries about trade tensions, with the Canadian dollar down against the greenback.

The Canadian dollar was sliding following President Trump's threat of a 35% tariff against Canada. But the bigger picture is what it might presage for U.S. negotiations with the European Union. The U.

President Donald Trump on Thursday announced that the U.S. would apply a 35% tariff to all imports from Canada beginning next month, reviving tensions with a major trade partner that had largely dissipated in recent weeks.