Shares of aluminum producer Alcoa slumped Monday on President Trump’s pledge to double tariffs on imported aluminum and steel, while its U.S. rival Century Aluminum surged on the prospect of a 50% duty starting Wednesday.

By Saeed Azhar, Kanchana Chakravarty and Sukriti Gupta NEW YORK (Reuters) - Wall Street's main indexes were mixed on Monday after President Donald Trump said he plans to double tariffs on imported steel and aluminum,

Mary Barra said at the Wall Street Journal’s Future of Everything conference in New York City she learned lessons from previous talks with Trump.

Experts, lawmakers, and industry people—alongside Canadian officials—have issued stark warnings about Trump's plan.

Even as U.S. courts question the legitimacy of President Trump’s tariffs, the president is showing no signs of backing off his favorite trade tool. On Wednesday, the tariffs that Mr. Trump imposed on foreign steel and aluminum are set to double to 50 percent,