By Adriano Marchese

Shares of Canadian auto-parts makers retreated after President Trump threatened higher tariffs on the sector's exports to the U.S.

Magna International's stock declined 4.4% to 52.75 Canadian dollars, Linamar's shares were down 4.2% to C$49.89 and Martinrea International was off by 2.6% to C$7.45.

Trump said his warning was in response to long-time tariffs Canada has on agricultural products from the U.S.

"If other egregious, long time Tariffs are not likewise dropped by Canada, I will substantially increase, on April 2nd, the Tariffs on Cars coming into the U.S. which will, essentially, permanently shut down the automobile manufacturing business in Canada," Trump said in a post on Truth Social Tuesday morning.

Separately, Trump ordered a 25% increase in tariffs on Canadian steel and aluminum entering the U.S., which he said in the same post would go into effect March 12.

On March 10, the Ontario government applied a 25% surcharge on all electricity exports to the U.S. as part of its own retaliatory measures to U.S. tariffs on Canada.

"This surcharge will affect 1.5 million homes and businesses in Michigan, Minnesota and New York, costing up to C$400,000 every day the surcharge remains in place," the Ontario government said in a statement Monday.

Trump said he will also declare a national emergency on electricity within the affected area.

Write to Adriano Marchese at adriano.marchese@wsj.com

(END) Dow Jones Newswires

March 11, 2025 11:30 ET (15:30 GMT)

Copyright (c) 2025 Dow Jones & Company, Inc.