Car stocks, including Tesla shares, will likely be volatile on Monday. Tariffs are the reason. Over the weekend, President Donald Trump went ahead with his plan to put 25% tariffs on goods from Mexico and Canada.

Prime Minister Justin Trudeau says Canada is ready to respond with 25 percent tariffs against C$155 billion worth of American goods.

President Donald Trump's threatened tariffs against Mexico, Canada and China went into effect Saturday evening, slapping a 25% wholesale tariff on both Mexico and Canada at once.

Many presidents use tariffs to force negotiations. But for President Trump, they are the point, a source of revenue as he pursues a Gilded Age vision.

Donald Trump has imposed new tariffs on goods entering the US from Canada, Mexico and China. The US president signed an executive order putting a 25% tariff - or tax on imports - on all goods coming from Canada and Mexico,